[RFC v9][PATCH 00/13] Kernel based checkpoint/restart - Kernel

This is a discussion on [RFC v9][PATCH 00/13] Kernel based checkpoint/restart - Kernel ; Checkpoint-restart (c/r): v9 adds support for multiple processes. (rebase to v2.6.28-rc3). We'd like to see these make their way into -mm. All comments have been addressed in this version. Please pull at least the first 11 patches, as they are ...

+ Reply to Thread
Results 1 to 17 of 17

Thread: [RFC v9][PATCH 00/13] Kernel based checkpoint/restart

  1. [RFC v9][PATCH 00/13] Kernel based checkpoint/restart

    Checkpoint-restart (c/r): v9 adds support for multiple processes.
    (rebase to v2.6.28-rc3).

    We'd like to see these make their way into -mm. All comments have
    been addressed in this version. Please pull at least the first 11
    patches, as they are similar to before.

    Patches 1-11 are basically as before, providing self- and external-
    c/r of a single process. Patches 12 and 13 are new, adding support
    for c/r of multiple processes.

    The git tree tracking v9, branch 'ckpt-v9' (and older versions):
    git://git.ncl.cs.columbia.edu/pub/git/linux-cr.git

    Restarting multiple processes requires 'mktree' userspace tool:
    git://git.ncl.cs.columbia.edu/pub/git/user-cr.git

    Oren.


    --
    Why do we want it? It allows containers to be moved between physical
    machines' kernels in the same way that VMWare can move VMs between
    physical machines' hypervisors. There are currently at least two
    out-of-tree implementations of this in the commercial world (IBM's
    Metacluster and Parallels' OpenVZ/Virtuozzo) and several in the academic
    world like Zap.

    Why do we need it in mainline now? Because we already have plenty of
    out-of-tree ones, and want to know what an in-tree one will be like.
    What *I* want right now is the extra review and scrutiny that comes with
    a mainline submission to make sure we're not going in a direction
    contrary to the community.

    This only supports pretty simple apps. But, I trust Ingo when he says:
    >> > > Generally, if something works for simple apps already (in a robust,
    >> > > compatible and supportable way) and users find it "very cool", then
    >> > > support for more complex apps is not far in the future. but if you
    >> > > want to support more complex apps straight away, it takes forever and
    >> > > gets ugly.


    We're *certainly* going to be changing the ABI (which is the format of
    the checkpoint). I'd like to follow the model that we used for
    ext4-dev, which is to make it very clear that this is a development-only
    feature for now. Perhaps we do that by making the interface only
    available through debugfs or something similar for now. Or, reserving
    the syscall numbers but require some runtime switch to be thrown before
    they can be used. I'm open to suggestions here.
    --

    --
    Todo:
    - Add support for x86-64 and improve ABI
    - Refine or change syscall interface
    - Handle multiple namespaces in a container (e.g. save the filesystem
    namespaces state with the file descriptors)
    - Security (without CAPS_SYS_ADMIN files restore may fail)

    Changelog:

    [2008-Nov-10] v9:
    - Support multiple processes c/r
    - Extend checkpoint header with archtiecture dependent header
    - Misc bug fixes (see individual changelogs)
    - Rebase to v2.6.28-rc3.

    [2008-Oct-29] v8:
    - Support "external" checkpoint
    - Include Dave Hansen's 'deny-checkpoint' patch
    - Split docs in Documentation/checkpoint/..., and improve contents

    [2008-Oct-17] v7:
    - Fix save/restore state of FPU
    - Fix argument given to kunmap_atomic() in memory dump/restore

    [2008-Oct-07] v6:
    - Balance all calls to cr_hbuf_get() with matching cr_hbuf_put()
    (even though it's not really needed)
    - Add assumptions and what's-missing to documentation
    - Misc fixes and cleanups

    [2008-Sep-11] v5:
    - Config is now 'def_bool n' by default
    - Improve memory dump/restore code (following Dave Hansen's comments)
    - Change dump format (and code) to allow chunks of
    instead of one long list of each
    - Fix use of follow_page() to avoid faulting in non-present pages
    - Memory restore now maps user pages explicitly to copy data into them,
    instead of reading directly to user space; got rid of mprotect_fixup()
    - Remove preempt_disable() when restoring debug registers
    - Rename headers files s/ckpt/checkpoint/
    - Fix misc bugs in files dump/restore
    - Fixes and cleanups on some error paths
    - Fix misc coding style

    [2008-Sep-09] v4:
    - Various fixes and clean-ups
    - Fix calculation of hash table size
    - Fix header structure alignment
    - Use stand list_... for cr_pgarr

    [2008-Aug-29] v3:
    - Various fixes and clean-ups
    - Use standard hlist_... for hash table
    - Better use of standard kmalloc/kfree

    [2008-Aug-20] v2:
    - Added Dump and restore of open files (regular and directories)
    - Added basic handling of shared objects, and improve handling of
    'parent tag' concept
    - Added documentation
    - Improved ABI, 64bit padding for image data
    - Improved locking when saving/restoring memory
    - Added UTS information to header (release, version, machine)
    - Cleanup extraction of filename from a file pointer
    - Refactor to allow easier reviewing
    - Remove requirement for CAPS_SYS_ADMIN until we come up with a
    security policy (this means that file restore may fail)
    - Other cleanup and response to comments for v1

    [2008-Jul-29] v1:
    - Initial version: support a single task with address space of only
    private anonymous or file-mapped VMAs; syscalls ignore pid/crid
    argument and act on current process.

    --
    At the containers mini-conference before OLS, the consensus among
    all the stakeholders was that doing checkpoint/restart in the kernel
    as much as possible was the best approach. With this approach, the
    kernel will export a relatively opaque 'blob' of data to userspace
    which can then be handed to the new kernel at restore time.

    This is different than what had been proposed before, which was
    that a userspace application would be responsible for collecting
    all of this data. We were also planning on adding lots of new,
    little kernel interfaces for all of the things that needed
    checkpointing. This unites those into a single, grand interface.

    The 'blob' will contain copies of select portions of kernel
    structures such as vmas and mm_structs. It will also contain
    copies of the actual memory that the process uses. Any changes
    in this blob's format between kernel revisions can be handled by
    an in-userspace conversion program.

    This is a similar approach to virtually all of the commercial
    checkpoint/restart products out there, as well as the research
    project Zap.

    These patches basically serialize internel kernel state and write
    it out to a file descriptor. The checkpoint and restore are done
    with two new system calls: sys_checkpoint and sys_restart.

    In this incarnation, they can only work checkpoint and restore a
    single task. The task's address space may consist of only private,
    simple vma's - anonymous or file-mapped. The open files may consist
    of only simple files and directories.
    --

    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

  2. [RFC v9][PATCH 12/13] Checkpoint multiple processes

    Checkpointing of multiple processes works by recording the tasks tree
    structure below a given task (usually this task is the container init).

    For a given task, do a DFS scan of the tasks tree and collect them
    into an array (keeping a reference to each task). Using DFS simplifies
    the recreation of tasks either in user space or kernel space. For each
    task collected, test if it can be checkpointed, and save its pid, tgid,
    and ppid.

    The actual work is divided into two passes: a first scan counts the
    tasks, then memory is allocated and a second scan fills the array.

    The logic is suitable for creation of processes during restart either
    in userspace or by the kernel.

    Currently we ignore threads and zombies, as well as session ids.

    Signed-off-by: Oren Laadan
    ---
    checkpoint/checkpoint.c | 228 +++++++++++++++++++++++++++++++++++++---
    checkpoint/sys.c | 16 +++
    include/linux/checkpoint.h | 3 +
    include/linux/checkpoint_hdr.h | 13 ++-
    4 files changed, 243 insertions(+), 17 deletions(-)

    diff --git a/checkpoint/checkpoint.c b/checkpoint/checkpoint.c
    index dd9f325..04b0c4a 100644
    --- a/checkpoint/checkpoint.c
    +++ b/checkpoint/checkpoint.c
    @@ -206,19 +206,6 @@ static int cr_write_task(struct cr_ctx *ctx, struct task_struct *t)
    {
    int ret;

    - /* TODO: verity that the task is frozen (unless self) */
    -
    - if (task->state == TASK_DEAD) {
    - pr_warning("c/r: task may not be in state TASK_DEAD\n");
    - return -EAGAIN;
    - }
    -
    - if (!atomic_read(&task->may_checkpoint)) {
    - pr_warning("c/r: task %d may not checkpoint\n",
    - task_pid_vnr(task));
    - return -BUSY;
    - }
    -
    ret = cr_write_task_struct(ctx, t);
    cr_debug("task_struct: ret %d\n", ret);
    if (ret < 0)
    @@ -241,6 +228,205 @@ static int cr_write_task(struct cr_ctx *ctx, struct task_struct *t)
    return ret;
    }

    +/* dump the entire state of a given task */
    +static int cr_write_all_tasks(struct cr_ctx *ctx)
    +{
    + int n, ret = 0;
    +
    + for (n = 0; n < ctx->tasks_nr; n++) {
    + cr_debug("dumping task #%d\n", n);
    + ret = cr_write_task(ctx, ctx->tasks_arr[n]);
    + if (ret < 0)
    + break;
    + }
    +
    + return ret;
    +}
    +
    +static int cr_may_checkpoint_task(struct task_struct *t, struct cr_ctx *ctx)
    +{
    + cr_debug("check %d\n", task_pid_nr_ns(t, ctx->root_nsproxy->pid_ns));
    +
    + if (t->state == TASK_DEAD) {
    + pr_warning("c/r: task %d is TASK_DEAD\n", task_pid_vnr(t));
    + return -EAGAIN;
    + }
    +
    + if (!atomic_read(&t->may_checkpoint)) {
    + pr_warning("c/r: task %d uncheckpointable\n", task_pid_vnr(t));
    + return -EBUSY;
    + }
    +
    + if (!ptrace_may_access(t, PTRACE_MODE_READ))
    + return -EPERM;
    +
    + /* FIXME: verify that the task is frozen (unless self) */
    +
    + /* FIXME: change this for nested containers */
    + if (task_nsproxy(t) != ctx->root_nsproxy)
    + return -EPERM;
    +
    + return 0;
    +}
    +
    +#define CR_HDR_PIDS_CHUNK 256
    +
    +static int cr_write_pids(struct cr_ctx *ctx)
    +{
    + struct cr_hdr_pids *hh;
    + struct pid_namespace *ns;
    + struct task_struct *task;
    + struct task_struct **tasks_arr;
    + int tasks_nr, n, ret = 0, pos = 0;
    +
    + ns = ctx->root_nsproxy->pid_ns;
    + tasks_arr = ctx->tasks_arr;
    + tasks_nr = ctx->tasks_nr;
    +
    + hh = cr_hbuf_get(ctx, sizeof(*hh) * CR_HDR_PIDS_CHUNK);
    +
    + while (tasks_nr > 0) {
    + rcu_read_lock();
    + for (n = min(tasks_nr, CR_HDR_PIDS_CHUNK); n; n--) {
    + task = tasks_arr[pos];
    +
    + /* is this task cool ? */
    + ret = cr_may_checkpoint_task(task, ctx);
    + if (ret < 0) {
    + rcu_read_unlock();
    + goto out;
    + }
    + hh[pos].vpid = task_pid_nr_ns(task, ns);
    + hh[pos].vtgid = task_tgid_nr_ns(task, ns);
    + hh[pos].vppid = task_tgid_nr_ns(task->real_parent, ns);
    + cr_debug("task[%d]: vpid %d vtgid %d parent %d\n", pos,
    + hh[pos].vpid, hh[pos].vtgid, hh[pos].vppid);
    + pos++;
    + }
    + rcu_read_unlock();
    +
    + n = min(tasks_nr, CR_HDR_PIDS_CHUNK);
    + ret = cr_kwrite(ctx, hh, n * sizeof(*hh));
    + if (ret < 0)
    + break;
    +
    + tasks_nr -= n;
    + }
    + out:
    + cr_hbuf_put(ctx, sizeof(*hh));
    + return ret;
    +}
    +
    +/* count number of tasks in tree (and optionally fill pid's in array) */
    +static int cr_tree_count_tasks(struct cr_ctx *ctx)
    +{
    + struct task_struct *root = ctx->root_task;
    + struct task_struct *task = root;
    + struct task_struct *parent = NULL;
    + struct task_struct **tasks_arr = ctx->tasks_arr;
    + int tasks_nr = ctx->tasks_nr;
    + int nr = 0;
    +
    + read_lock(&tasklist_lock);
    +
    + /* count tasks via DFS scan of the tree */
    + while (1) {
    + if (tasks_arr) {
    + /* unlikely, but ... */
    + if (nr == tasks_nr)
    + return -EBUSY; /* cleanup in cr_ctx_free() */
    + tasks_arr[nr] = task;
    + get_task_struct(task);
    + }
    +
    + nr++;
    +
    + /* if has children - proceed with child */
    + if (!list_empty(&task->children)) {
    + parent = task;
    + task = list_entry(task->children.next,
    + struct task_struct, sibling);
    + continue;
    + }
    +
    + while (task != root) {
    + /* if has sibling - proceed with sibling */
    + if (!list_is_last(&task->sibling, &parent->children)) {
    + task = list_entry(task->sibling.next,
    + struct task_struct, sibling);
    + break;
    + }
    +
    + /* else, trace back to parent and proceed */
    + task = parent;
    + parent = parent->real_parent;
    + }
    +
    + if (task == root)
    + break;
    + }
    +
    + read_unlock(&tasklist_lock);
    + return nr;
    +}
    +
    +/*
    + * cr_build_tree - scan the tasks tree in DFS order and fill in array
    + * @ctx: checkpoint context
    + *
    + * Using DFS order simplifies the restart logic to re-create the tasks.
    + *
    + * On success, ctx->tasks_arr will be allocated and populated with all
    + * tasks (reference taken), and ctx->tasks_nr will hold the total count.
    + * The array is cleaned up by cr_ctx_free().
    + */
    +static int cr_build_tree(struct cr_ctx *ctx)
    +{
    + int n, m;
    +
    + /* count tasks (no side effects) */
    + n = cr_tree_count_tasks(ctx);
    +
    + ctx->tasks_nr = n;
    + ctx->tasks_arr = kzalloc(n * sizeof(*ctx->tasks_arr), GFP_KERNEL);
    + if (!ctx->tasks_arr)
    + return -ENOMEM;
    +
    + /* count again (now will fill array) */
    + m = cr_tree_count_tasks(ctx);
    +
    + /* unlikely, but ... (cleanup in cr_ctx_free) */
    + if (m < 0)
    + return m;
    + else if (m != n)
    + return -EBUSY;
    +
    + return 0;
    +}
    +
    +/* dump the array that describes the tasks tree */
    +static int cr_write_tree(struct cr_ctx *ctx)
    +{
    + struct cr_hdr h;
    + struct cr_hdr_tree *hh;
    + int ret;
    +
    + h.type = CR_HDR_TREE;
    + h.len = sizeof(*hh);
    + h.parent = 0;
    +
    + hh = cr_hbuf_get(ctx, sizeof(*hh));
    + hh->tasks_nr = ctx->tasks_nr;
    +
    + ret = cr_write_obj(ctx, &h, hh);
    + cr_hbuf_put(ctx, sizeof(*hh));
    + if (ret < 0)
    + return ret;
    +
    + ret = cr_write_pids(ctx);
    + return ret;
    +}
    +
    static int cr_get_container(struct cr_ctx *ctx, pid_t pid)
    {
    struct task_struct *task = NULL;
    @@ -258,7 +444,7 @@ static int cr_get_container(struct cr_ctx *ctx, pid_t pid)
    if (!task)
    goto out;

    -#if 0 /* enable to use containers */
    +#if 0 /* enable with containers */
    if (!is_container_init(task)) {
    err = -EINVAL;
    goto out;
    @@ -280,7 +466,7 @@ static int cr_get_container(struct cr_ctx *ctx, pid_t pid)
    if (!nsproxy)
    goto out;

    - /* TODO: verify that the container is frozen */
    + /* FIXME: verify that the container is frozen */

    ctx->root_task = task;
    ctx->root_nsproxy = nsproxy;
    @@ -319,12 +505,22 @@ int do_checkpoint(struct cr_ctx *ctx, pid_t pid)
    ret = cr_ctx_checkpoint(ctx, pid);
    if (ret < 0)
    goto out;
    +
    + ret = cr_build_tree(ctx);
    + if (ret < 0)
    + goto out;
    +
    ret = cr_write_head(ctx);
    if (ret < 0)
    goto out;
    - ret = cr_write_task(ctx, ctx->root_task);
    + ret = cr_write_tree(ctx);
    if (ret < 0)
    goto out;
    +
    + ret = cr_write_all_tasks(ctx);
    + if (ret < 0)
    + goto out;
    +
    ret = cr_write_tail(ctx);
    if (ret < 0)
    goto out;
    diff --git a/checkpoint/sys.c b/checkpoint/sys.c
    index dfe63ca..fbaf683 100644
    --- a/checkpoint/sys.c
    +++ b/checkpoint/sys.c
    @@ -130,6 +130,19 @@ void cr_hbuf_put(struct cr_ctx *ctx, int n)
    * restart operation, and persists until the operation is completed.
    */

    +static void cr_task_arr_free(struct cr_ctx *ctx)
    +{
    + int n;
    +
    + for (n = 0; n < ctx->tasks_nr; n++) {
    + if (ctx->tasks_arr[n]) {
    + put_task_struct(ctx->tasks_arr[n]);
    + ctx->tasks_arr[n] = NULL;
    + }
    + }
    + kfree(ctx->tasks_arr);
    +}
    +
    static void cr_ctx_free(struct cr_ctx *ctx)
    {
    if (ctx->file)
    @@ -143,6 +156,9 @@ static void cr_ctx_free(struct cr_ctx *ctx)
    cr_pgarr_free(ctx);
    cr_objhash_free(ctx);

    + if (ctx->tasks_arr)
    + cr_task_arr_free(ctx);
    +
    if (ctx->root_nsproxy)
    put_nsproxy(ctx->root_nsproxy);
    if (ctx->root_task)
    diff --git a/include/linux/checkpoint.h b/include/linux/checkpoint.h
    index 74a8597..b142171 100644
    --- a/include/linux/checkpoint.h
    +++ b/include/linux/checkpoint.h
    @@ -34,6 +34,9 @@ struct cr_ctx {
    void *hbuf; /* temporary buffer for headers */
    int hpos; /* position in headers buffer */

    + struct task_struct **tasks_arr; /* array of all tasks in container */
    + int tasks_nr; /* size of tasks array */
    +
    struct cr_objhash *objhash; /* hash for shared objects */

    struct list_head pgarr_list; /* page array to dump VMA contents */
    diff --git a/include/linux/checkpoint_hdr.h b/include/linux/checkpoint_hdr.h
    index 3a21179..5114bdd 100644
    --- a/include/linux/checkpoint_hdr.h
    +++ b/include/linux/checkpoint_hdr.h
    @@ -35,7 +35,8 @@ enum {
    CR_HDR_STRING,
    CR_HDR_FNAME,

    - CR_HDR_TASK = 101,
    + CR_HDR_TREE = 101,
    + CR_HDR_TASK,
    CR_HDR_THREAD,
    CR_HDR_CPU,

    @@ -71,6 +72,16 @@ struct cr_hdr_tail {
    __u64 magic;
    } __attribute__((aligned(8)));

    +struct cr_hdr_tree {
    + __u32 tasks_nr;
    +} __attribute__((aligned(8)));
    +
    +struct cr_hdr_pids {
    + __s32 vpid;
    + __s32 vtgid;
    + __s32 vppid;
    +} __attribute__((aligned(8)));
    +
    struct cr_hdr_task {
    __u32 state;
    __u32 exit_state;
    --
    1.5.4.3

    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

  3. [RFC v9][PATCH 09/13] Restore open file descriprtors

    Restore open file descriptors: for each FD read 'struct cr_hdr_fd_ent'
    and lookup objref in the hash table; if not found (first occurence), read
    in 'struct cr_hdr_fd_data', create a new FD and register in the hash.
    Otherwise attach the file pointer from the hash as an FD.

    This patch only handles basic FDs - regular files, directories and also
    symbolic links.

    Changelog[v6]:
    - Balance all calls to cr_hbuf_get() with matching cr_hbuf_put()
    (even though it's not really needed)

    Signed-off-by: Oren Laadan
    Acked-by: Serge Hallyn
    Signed-off-by: Dave Hansen
    ---
    checkpoint/Makefile | 2 +-
    checkpoint/restart.c | 4 +
    checkpoint/rstr_file.c | 246 ++++++++++++++++++++++++++++++++++++++++++++
    include/linux/checkpoint.h | 1 +
    4 files changed, 252 insertions(+), 1 deletions(-)
    create mode 100644 checkpoint/rstr_file.c

    diff --git a/checkpoint/Makefile b/checkpoint/Makefile
    index 7496695..88bbc10 100644
    --- a/checkpoint/Makefile
    +++ b/checkpoint/Makefile
    @@ -3,4 +3,4 @@
    #

    obj-$(CONFIG_CHECKPOINT_RESTART) += sys.o checkpoint.o restart.o objhash.o \
    - ckpt_mem.o rstr_mem.o ckpt_file.o
    + ckpt_mem.o rstr_mem.o ckpt_file.o rstr_file.o
    diff --git a/checkpoint/restart.c b/checkpoint/restart.c
    index 2fbada6..1d1f2a7 100644
    --- a/checkpoint/restart.c
    +++ b/checkpoint/restart.c
    @@ -219,6 +219,10 @@ static int cr_read_task(struct cr_ctx *ctx)
    cr_debug("memory: ret %d\n", ret);
    if (ret < 0)
    goto out;
    + ret = cr_read_files(ctx);
    + cr_debug("files: ret %d\n", ret);
    + if (ret < 0)
    + goto out;
    ret = cr_read_thread(ctx);
    cr_debug("thread: ret %d\n", ret);
    if (ret < 0)
    diff --git a/checkpoint/rstr_file.c b/checkpoint/rstr_file.c
    new file mode 100644
    index 0000000..08bb049
    --- /dev/null
    +++ b/checkpoint/rstr_file.c
    @@ -0,0 +1,246 @@
    +/*
    + * Checkpoint file descriptors
    + *
    + * Copyright (C) 2008 Oren Laadan
    + *
    + * This file is subject to the terms and conditions of the GNU General Public
    + * License. See the file COPYING in the main directory of the Linux
    + * distribution for more details.
    + */
    +
    +#include
    +#include
    +#include
    +#include
    +#include
    +#include
    +#include
    +#include
    +#include
    +
    +#include "checkpoint_file.h"
    +
    +static int cr_close_all_fds(struct files_struct *files)
    +{
    + int *fdtable;
    + int nfds;
    +
    + nfds = cr_scan_fds(files, &fdtable);
    + if (nfds < 0)
    + return nfds;
    + while (nfds--)
    + sys_close(fdtable[nfds]);
    + kfree(fdtable);
    + return 0;
    +}
    +
    +/**
    + * cr_attach_file - attach a lonely file ptr to a file descriptor
    + * @file: lonely file pointer
    + */
    +static int cr_attach_file(struct file *file)
    +{
    + int fd = get_unused_fd_flags(0);
    +
    + if (fd >= 0) {
    + fsnotify_open(file->f_path.dentry);
    + fd_install(fd, file);
    + }
    + return fd;
    +}
    +
    +/**
    + * cr_attach_get_file - attach (and get) lonely file ptr to a file descriptor
    + * @file: lonely file pointer
    + */
    +static int cr_attach_get_file(struct file *file)
    +{
    + int fd = get_unused_fd_flags(0);
    +
    + if (fd >= 0) {
    + fsnotify_open(file->f_path.dentry);
    + fd_install(fd, file);
    + get_file(file);
    + }
    + return fd;
    +}
    +
    +#define CR_SETFL_MASK (O_APPEND|O_NONBLOCK|O_NDELAY|FASYNC|O_DIRECT|O_NO ATIME)
    +
    +/* cr_read_fd_data - restore the state of a given file pointer */
    +static int
    +cr_read_fd_data(struct cr_ctx *ctx, struct files_struct *files, int parent)
    +{
    + struct cr_hdr_fd_data *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + struct file *file;
    + int rparent, ret;
    + int fd = 0; /* pacify gcc warning */
    +
    + rparent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_FD_DATA);
    + cr_debug("rparent %d parent %d flags %#x mode %#x how %d\n",
    + rparent, parent, hh->f_flags, hh->f_mode, hh->fd_type);
    + if (rparent < 0) {
    + ret = parent;
    + goto out;
    + }
    +
    + ret = -EINVAL;
    +
    + if (rparent != parent)
    + goto out;
    +
    + /* FIX: more sanity checks on f_flags, f_mode etc */
    +
    + switch (hh->fd_type) {
    + case CR_FD_FILE:
    + case CR_FD_DIR:
    + case CR_FD_LINK:
    + file = cr_read_open_fname(ctx, hh->f_flags, hh->f_mode);
    + break;
    + default:
    + goto out;
    + }
    +
    + if (IS_ERR(file)) {
    + ret = PTR_ERR(file);
    + goto out;
    + }
    +
    + /* FIX: need to restore uid, gid, owner etc */
    +
    + fd = cr_attach_file(file); /* no need to cleanup 'file' below */
    + if (fd < 0) {
    + filp_close(file, NULL);
    + ret = fd;
    + goto out;
    + }
    +
    + /* register new tuple in hash table */
    + ret = cr_obj_add_ref(ctx, (void *) file, parent, CR_OBJ_FILE, 0);
    + if (ret < 0)
    + goto out;
    + ret = sys_fcntl(fd, F_SETFL, hh->f_flags & CR_SETFL_MASK);
    + if (ret < 0)
    + goto out;
    + ret = vfs_llseek(file, hh->f_pos, SEEK_SET);
    + if (ret == -ESPIPE) /* ignore error on non-seekable files */
    + ret = 0;
    +
    + ret = 0;
    + out:
    + cr_hbuf_put(ctx, sizeof(*hh));
    + return ret < 0 ? ret : fd;
    +}
    +
    +/**
    + * cr_read_fd_ent - restore the state of a given file descriptor
    + * @ctx: checkpoint context
    + * @files: files_struct pointer
    + * @parent: parent objref
    + *
    + * Restores the state of a file descriptor; looks up the objref (in the
    + * header) in the hash table, and if found picks the matching file and
    + * use it; otherwise calls cr_read_fd_data to restore the file too.
    + */
    +static int
    +cr_read_fd_ent(struct cr_ctx *ctx, struct files_struct *files, int parent)
    +{
    + struct cr_hdr_fd_ent *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + struct file *file;
    + int newfd, rparent, ret;
    +
    + rparent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_FD_ENT);
    + cr_debug("rparent %d parent %d ref %d fd %d c.o.e %d\n",
    + rparent, parent, hh->objref, hh->fd, hh->close_on_exec);
    + if (rparent < 0) {
    + ret = rparent;
    + goto out;
    + }
    +
    + ret = -EINVAL;
    +
    + if (rparent != parent)
    + goto out;
    + if (hh->objref <= 0)
    + goto out;
    +
    + file = cr_obj_get_by_ref(ctx, hh->objref, CR_OBJ_FILE);
    + if (IS_ERR(file)) {
    + ret = PTR_ERR(file);
    + goto out;
    + }
    +
    + if (file) {
    + /* reuse file descriptor found in the hash table */
    + newfd = cr_attach_get_file(file);
    + } else {
    + /* create new file pointer (and register in hash table) */
    + newfd = cr_read_fd_data(ctx, files, hh->objref);
    + }
    +
    + if (newfd < 0) {
    + ret = newfd;
    + goto out;
    + }
    +
    + cr_debug("newfd got %d wanted %d\n", newfd, hh->fd);
    +
    + /* if newfd isn't desired fd then reposition it */
    + if (newfd != hh->fd) {
    + ret = sys_dup2(newfd, hh->fd);
    + if (ret < 0)
    + goto out;
    + sys_close(newfd);
    + }
    +
    + if (hh->close_on_exec)
    + set_close_on_exec(hh->fd, 1);
    +
    + ret = 0;
    + out:
    + cr_hbuf_put(ctx, sizeof(*hh));
    + return ret;
    +}
    +
    +int cr_read_files(struct cr_ctx *ctx)
    +{
    + struct cr_hdr_files *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + struct files_struct *files = current->files;
    + int i, parent, ret;
    +
    + parent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_FILES);
    + if (parent < 0) {
    + ret = parent;
    + goto out;
    + }
    +
    + ret = -EINVAL;
    +#if 0 /* activate when containers are used */
    + if (parent != task_pid_vnr(current))
    + goto out;
    +#endif
    + cr_debug("objref %d nfds %d\n", hh->objref, hh->nfds);
    + if (hh->objref < 0 || hh->nfds < 0)
    + goto out;
    +
    + if (hh->nfds > sysctl_nr_open) {
    + ret = -EMFILE;
    + goto out;
    + }
    +
    + /* point of no return -- close all file descriptors */
    + ret = cr_close_all_fds(files);
    + if (ret < 0)
    + goto out;
    +
    + for (i = 0; i < hh->nfds; i++) {
    + ret = cr_read_fd_ent(ctx, files, hh->objref);
    + if (ret < 0)
    + break;
    + }
    +
    + ret = 0;
    + out:
    + cr_hbuf_put(ctx, sizeof(*hh));
    + return ret;
    +}
    diff --git a/include/linux/checkpoint.h b/include/linux/checkpoint.h
    index bca7aef..7e3402f 100644
    --- a/include/linux/checkpoint.h
    +++ b/include/linux/checkpoint.h
    @@ -84,6 +84,7 @@ extern int cr_write_files(struct cr_ctx *ctx, struct task_struct *t);

    extern int do_restart(struct cr_ctx *ctx, pid_t pid);
    extern int cr_read_mm(struct cr_ctx *ctx);
    +extern int cr_read_files(struct cr_ctx *ctx);

    #define cr_debug(fmt, args...) \
    pr_debug("[%d:c/r:%s] " fmt, task_pid_vnr(current), __func__, ## args)
    --
    1.5.4.3

    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

  4. [RFC v9][PATCH 10/13] External checkpoint of a task other than ourself

    Now we can do "external" checkpoint, i.e. act on another task.

    sys_checkpoint() now looks up the target pid (in our namespace) and
    checkpoints that corresponding task. That task should be the root of
    a container.

    sys_restart() remains the same, as the restart is always done in the
    context of the restarting task.

    Signed-off-by: Oren Laadan
    Acked-by: Serge Hallyn
    ---
    checkpoint/checkpoint.c | 71 ++++++++++++++++++++++++++++++++++++++++++--
    checkpoint/restart.c | 4 +-
    checkpoint/sys.c | 6 ++++
    include/linux/checkpoint.h | 2 +
    4 files changed, 78 insertions(+), 5 deletions(-)

    diff --git a/checkpoint/checkpoint.c b/checkpoint/checkpoint.c
    index 700f829..a20f961 100644
    --- a/checkpoint/checkpoint.c
    +++ b/checkpoint/checkpoint.c
    @@ -10,6 +10,7 @@

    #include
    #include
    +#include
    #include
    #include
    #include
    @@ -205,6 +206,13 @@ static int cr_write_task(struct cr_ctx *ctx, struct task_struct *t)
    {
    int ret;

    + /* TODO: verity that the task is frozen (unless self) */
    +
    + if (task->state == TASK_DEAD) {
    + pr_warning("c/r: task may not be in state TASK_DEAD\n");
    + return -EAGAIN;
    + }
    +
    ret = cr_write_task_struct(ctx, t);
    cr_debug("task_struct: ret %d\n", ret);
    if (ret < 0)
    @@ -227,10 +235,67 @@ static int cr_write_task(struct cr_ctx *ctx, struct task_struct *t)
    return ret;
    }

    -static int cr_ctx_checkpoint(struct cr_ctx *ctx, pid_t pid)
    +static int cr_get_container(struct cr_ctx *ctx, pid_t pid)
    {
    + struct task_struct *task = NULL;
    + struct nsproxy *nsproxy = NULL;
    + int err = -ESRCH;
    +
    ctx->root_pid = pid;

    + read_lock(&tasklist_lock);
    + task = find_task_by_vpid(pid);
    + if (task)
    + get_task_struct(task);
    + read_unlock(&tasklist_lock);
    +
    + if (!task)
    + goto out;
    +
    +#if 0 /* enable to use containers */
    + if (!is_container_init(task)) {
    + err = -EINVAL;
    + goto out;
    + }
    +#endif
    +
    + if (!ptrace_may_access(task, PTRACE_MODE_READ)) {
    + err = -EPERM;
    + goto out;
    + }
    +
    + rcu_read_lock();
    + if (task_nsproxy(task)) {
    + nsproxy = task_nsproxy(task);
    + get_nsproxy(nsproxy);
    + }
    + rcu_read_unlock();
    +
    + if (!nsproxy)
    + goto out;
    +
    + /* TODO: verify that the container is frozen */
    +
    + ctx->root_task = task;
    + ctx->root_nsproxy = nsproxy;
    +
    + return 0;
    +
    + out:
    + if (task)
    + put_task_struct(task);
    + return err;
    +}
    +
    +/* setup checkpoint-specific parts of ctx */
    +static int cr_ctx_checkpoint(struct cr_ctx *ctx, pid_t pid)
    +{
    + int ret;
    +
    + ret = cr_get_container(ctx, pid);
    + if (ret < 0)
    + return ret;
    +
    /*
    * assume checkpointer is in container's root vfs
    * FIXME: this works for now, but will change with real containers
    @@ -245,13 +310,13 @@ int do_checkpoint(struct cr_ctx *ctx, pid_t pid)
    {
    int ret;

    - ret = cr_ctx_checkpoint(ctx);
    + ret = cr_ctx_checkpoint(ctx, pid);
    if (ret < 0)
    goto out;
    ret = cr_write_head(ctx);
    if (ret < 0)
    goto out;
    - ret = cr_write_task(ctx, current);
    + ret = cr_write_task(ctx, ctx->root_task);
    if (ret < 0)
    goto out;
    ret = cr_write_tail(ctx);
    diff --git a/checkpoint/restart.c b/checkpoint/restart.c
    index 1d1f2a7..8bd9d4a 100644
    --- a/checkpoint/restart.c
    +++ b/checkpoint/restart.c
    @@ -235,7 +235,7 @@ static int cr_read_task(struct cr_ctx *ctx)
    }

    /* setup restart-specific parts of ctx */
    -static int cr_ctx_restart(struct cr_ctx *ctx)
    +static int cr_ctx_restart(struct cr_ctx *ctx, pid_t pid)
    {
    return 0;
    }
    @@ -244,7 +244,7 @@ int do_restart(struct cr_ctx *ctx, pid_t pid)
    {
    int ret;

    - ret = cr_ctx_restart(ctx);
    + ret = cr_ctx_restart(ctx, pid);
    if (ret < 0)
    goto out;
    ret = cr_read_head(ctx);
    diff --git a/checkpoint/sys.c b/checkpoint/sys.c
    index b640bee..dfe63ca 100644
    --- a/checkpoint/sys.c
    +++ b/checkpoint/sys.c
    @@ -9,6 +9,7 @@
    */

    #include
    +#include
    #include
    #include
    #include
    @@ -142,6 +143,11 @@ static void cr_ctx_free(struct cr_ctx *ctx)
    cr_pgarr_free(ctx);
    cr_objhash_free(ctx);

    + if (ctx->root_nsproxy)
    + put_nsproxy(ctx->root_nsproxy);
    + if (ctx->root_task)
    + put_task_struct(ctx->root_task);
    +
    kfree(ctx);
    }

    diff --git a/include/linux/checkpoint.h b/include/linux/checkpoint.h
    index 7e3402f..b807e85 100644
    --- a/include/linux/checkpoint.h
    +++ b/include/linux/checkpoint.h
    @@ -19,6 +19,8 @@ struct cr_ctx {
    int crid; /* unique checkpoint id */

    pid_t root_pid; /* container identifier */
    + struct task_struct *root_task; /* container root task */
    + struct nsproxy *root_nsproxy; /* container root nsproxy */

    unsigned long flags;
    unsigned long oflags; /* restart: old flags */
    --
    1.5.4.3

    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

  5. [RFC v9][PATCH 06/13] Restore memory address space

    Restoring the memory address space begins with nuking the existing one
    of the current process, and then reading the VMA state and contents.
    Call do_mmap_pgoffset() for each VMA and then read in the data.

    Changelog[v9]:
    - Introduce cr_ctx_checkpoint() for checkpoint-specific ctx setup

    Changelog[v7]:
    - Fix argument given to kunmap_atomic() in memory dump/restore

    Changelog[v6]:
    - Balance all calls to cr_hbuf_get() with matching cr_hbuf_put()
    (even though it's not really needed)

    Changelog[v5]:
    - Improve memory restore code (following Dave Hansen's comments)
    - Change dump format (and code) to allow chunks of
    instead of one long list of each
    - Memory restore now maps user pages explicitly to copy data into them,
    instead of reading directly to user space; got rid of mprotect_fixup()

    Changelog[v4]:
    - Use standard list_... for cr_pgarr


    Signed-off-by: Oren Laadan
    Acked-by: Serge Hallyn
    Signed-off-by: Dave Hansen
    ---
    arch/x86/include/asm/checkpoint_hdr.h | 5 +
    arch/x86/mm/restart.c | 64 ++++++-
    checkpoint/Makefile | 2 +-
    checkpoint/checkpoint_arch.h | 2 +
    checkpoint/checkpoint_mem.h | 5 +
    checkpoint/restart.c | 51 +++++
    checkpoint/rstr_mem.c | 384 +++++++++++++++++++++++++++++++++
    include/linux/checkpoint.h | 3 +
    8 files changed, 513 insertions(+), 3 deletions(-)
    create mode 100644 checkpoint/rstr_mem.c

    diff --git a/arch/x86/include/asm/checkpoint_hdr.h b/arch/x86/include/asm/checkpoint_hdr.h
    index 33f4c70..d13db9b 100644
    --- a/arch/x86/include/asm/checkpoint_hdr.h
    +++ b/arch/x86/include/asm/checkpoint_hdr.h
    @@ -87,4 +87,9 @@ struct cr_hdr_mm_context {
    __s16 nldt;
    } __attribute__((aligned(8)));

    +#ifdef __KERNEL__
    +/* misc prototypes from kernel (not defined elsewhere) */
    +asmlinkage int sys_modify_ldt(int func, void __user *ptr, unsigned long bytecount);
    +#endif
    +
    #endif /* __ASM_X86_CKPT_HDR__H */
    diff --git a/arch/x86/mm/restart.c b/arch/x86/mm/restart.c
    index 45ad790..3f9e15b 100644
    --- a/arch/x86/mm/restart.c
    +++ b/arch/x86/mm/restart.c
    @@ -52,8 +52,10 @@ int cr_read_thread(struct cr_ctx *ctx)

    size = sizeof(*desc) * GDT_ENTRY_TLS_ENTRIES;
    desc = kmalloc(size, GFP_KERNEL);
    - if (!desc)
    - return -ENOMEM;
    + if (!desc) {
    + ret = -ENOMEM;
    + goto out;
    + }

    ret = cr_kread(ctx, desc, size);
    if (ret >= 0) {
    @@ -230,3 +232,61 @@ int cr_read_head_arch(struct cr_ctx *ctx)

    return ret;
    }
    +
    +int cr_read_mm_context(struct cr_ctx *ctx, struct mm_struct *mm, int parent)
    +{
    + struct cr_hdr_mm_context *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + int n, rparent, ret = -EINVAL;
    +
    + rparent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_MM_CONTEXT);
    + cr_debug("parent %d rparent %d nldt %d\n", parent, rparent, hh->nldt);
    + if (rparent < 0) {
    + ret = rparent;
    + goto out;
    + }
    + if (rparent != parent)
    + goto out;
    +
    + if (hh->nldt < 0 || hh->ldt_entry_size != LDT_ENTRY_SIZE)
    + goto out;
    +
    + /*
    + * to utilize the syscall modify_ldt() we first convert the data
    + * in the checkpoint image from 'struct desc_struct' to 'struct
    + * user_desc' with reverse logic of include/asm/desc.h:fill_ldt()
    + */
    +
    + for (n = 0; n < hh->nldt; n++) {
    + struct user_desc info;
    + struct desc_struct desc;
    + mm_segment_t old_fs;
    +
    + ret = cr_kread(ctx, &desc, LDT_ENTRY_SIZE);
    + if (ret < 0)
    + goto out;
    +
    + info.entry_number = n;
    + info.base_addr = desc.base0 | (desc.base1 << 16);
    + info.limit = desc.limit0;
    + info.seg_32bit = desc.d;
    + info.contents = desc.type >> 2;
    + info.read_exec_only = (desc.type >> 1) ^ 1;
    + info.limit_in_pages = desc.g;
    + info.seg_not_present = desc.p ^ 1;
    + info.useable = desc.avl;
    +
    + old_fs = get_fs();
    + set_fs(get_ds());
    + ret = sys_modify_ldt(1, (struct user_desc __user *) &info,
    + sizeof(info));
    + set_fs(old_fs);
    +
    + if (ret < 0)
    + goto out;
    + }
    +
    + ret = 0;
    + out:
    + cr_hbuf_put(ctx, sizeof(*hh));
    + return ret;
    +}
    diff --git a/checkpoint/Makefile b/checkpoint/Makefile
    index 3a0df6d..ac35033 100644
    --- a/checkpoint/Makefile
    +++ b/checkpoint/Makefile
    @@ -3,4 +3,4 @@
    #

    obj-$(CONFIG_CHECKPOINT_RESTART) += sys.o checkpoint.o restart.o \
    - ckpt_mem.o
    + ckpt_mem.o rstr_mem.o
    diff --git a/checkpoint/checkpoint_arch.h b/checkpoint/checkpoint_arch.h
    index f06c7eb..39c8224 100644
    --- a/checkpoint/checkpoint_arch.h
    +++ b/checkpoint/checkpoint_arch.h
    @@ -9,3 +9,5 @@ extern int cr_write_mm_context(struct cr_ctx *ctx,
    extern int cr_read_head_arch(struct cr_ctx *ctx);
    extern int cr_read_thread(struct cr_ctx *ctx);
    extern int cr_read_cpu(struct cr_ctx *ctx);
    +extern int cr_read_mm_context(struct cr_ctx *ctx,
    + struct mm_struct *mm, int parent);
    diff --git a/checkpoint/checkpoint_mem.h b/checkpoint/checkpoint_mem.h
    index 85546f4..85a5cf3 100644
    --- a/checkpoint/checkpoint_mem.h
    +++ b/checkpoint/checkpoint_mem.h
    @@ -38,4 +38,9 @@ static inline int cr_pgarr_is_full(struct cr_pgarr *pgarr)
    return (pgarr->nr_used == CR_PGARR_TOTAL);
    }

    +static inline int cr_pgarr_nr_free(struct cr_pgarr *pgarr)
    +{
    + return CR_PGARR_TOTAL - pgarr->nr_used;
    +}
    +
    #endif /* _CHECKPOINT_CKPT_MEM_H_ */
    diff --git a/checkpoint/restart.c b/checkpoint/restart.c
    index 56bab40..2fbada6 100644
    --- a/checkpoint/restart.c
    +++ b/checkpoint/restart.c
    @@ -78,6 +78,44 @@ int cr_read_string(struct cr_ctx *ctx, void *str, int len)
    return cr_read_obj_type(ctx, str, len, CR_HDR_STRING);
    }

    +/**
    + * cr_read_fname - read a file name
    + * @ctx: checkpoint context
    + * @fname: buffer
    + * @n: buffer length
    + */
    +int cr_read_fname(struct cr_ctx *ctx, void *fname, int flen)
    +{
    + return cr_read_obj_type(ctx, fname, flen, CR_HDR_FNAME);
    +}
    +
    +/**
    + * cr_read_open_fname - read a file name and open a file
    + * @ctx: checkpoint context
    + * @flags: file flags
    + * @mode: file mode
    + */
    +struct file *cr_read_open_fname(struct cr_ctx *ctx, int flags, int mode)
    +{
    + struct file *file;
    + char *fname;
    + int ret;
    +
    + fname = kmalloc(PATH_MAX, GFP_KERNEL);
    + if (!fname)
    + return ERR_PTR(-ENOMEM);
    +
    + ret = cr_read_fname(ctx, fname, PATH_MAX);
    + cr_debug("fname '%s' flags %#x mode %#x\n", fname, flags, mode);
    + if (ret >= 0)
    + file = filp_open(fname, flags, mode);
    + else
    + file = ERR_PTR(ret);
    +
    + kfree(fname);
    + return file;
    +}
    +
    /* read the checkpoint header */
    static int cr_read_head(struct cr_ctx *ctx)
    {
    @@ -177,6 +215,10 @@ static int cr_read_task(struct cr_ctx *ctx)
    cr_debug("task_struct: ret %d\n", ret);
    if (ret < 0)
    goto out;
    + ret = cr_read_mm(ctx);
    + cr_debug("memory: ret %d\n", ret);
    + if (ret < 0)
    + goto out;
    ret = cr_read_thread(ctx);
    cr_debug("thread: ret %d\n", ret);
    if (ret < 0)
    @@ -188,10 +230,19 @@ static int cr_read_task(struct cr_ctx *ctx)
    return ret;
    }

    +/* setup restart-specific parts of ctx */
    +static int cr_ctx_restart(struct cr_ctx *ctx)
    +{
    + return 0;
    +}
    +
    int do_restart(struct cr_ctx *ctx, pid_t pid)
    {
    int ret;

    + ret = cr_ctx_restart(ctx);
    + if (ret < 0)
    + goto out;
    ret = cr_read_head(ctx);
    if (ret < 0)
    goto out;
    diff --git a/checkpoint/rstr_mem.c b/checkpoint/rstr_mem.c
    new file mode 100644
    index 0000000..6713f4f
    --- /dev/null
    +++ b/checkpoint/rstr_mem.c
    @@ -0,0 +1,384 @@
    +/*
    + * Restart memory contents
    + *
    + * Copyright (C) 2008 Oren Laadan
    + *
    + * This file is subject to the terms and conditions of the GNU General Public
    + * License. See the file COPYING in the main directory of the Linux
    + * distribution for more details.
    + */
    +
    +#include
    +#include
    +#include
    +#include
    +#include
    +#include
    +#include
    +#include
    +#include
    +#include
    +#include
    +#include
    +
    +#include "checkpoint_arch.h"
    +#include "checkpoint_mem.h"
    +
    +/*
    + * Unlike checkpoint, restart is executed in the context of each restarting
    + * process: vma regions are restored via a call to mmap(), and the data is
    + * read into the address space of the current process.
    + */
    +
    +
    +/**
    + * cr_read_pages_vaddrs - read addresses of pages to page-array chain
    + * @ctx - restart context
    + * @nr_pages - number of address to read
    + */
    +static int cr_read_pages_vaddrs(struct cr_ctx *ctx, unsigned long nr_pages)
    +{
    + struct cr_pgarr *pgarr;
    + unsigned long *vaddrp;
    + int nr, ret;
    +
    + while (nr_pages) {
    + pgarr = cr_pgarr_current(ctx);
    + if (!pgarr)
    + return -ENOMEM;
    + nr = cr_pgarr_nr_free(pgarr);
    + if (nr > nr_pages)
    + nr = nr_pages;
    + vaddrp = &pgarr->vaddrs[pgarr->nr_used];
    + ret = cr_kread(ctx, vaddrp, nr * sizeof(unsigned long));
    + if (ret < 0)
    + return ret;
    + pgarr->nr_used += nr;
    + nr_pages -= nr;
    + }
    + return 0;
    +}
    +
    +static int cr_page_read(struct cr_ctx *ctx, struct page *page, char *buf)
    +{
    + void *ptr;
    + int ret;
    +
    + ret = cr_kread(ctx, buf, PAGE_SIZE);
    + if (ret < 0)
    + return ret;
    +
    + ptr = kmap_atomic(page, KM_USER1);
    + memcpy(ptr, buf, PAGE_SIZE);
    + kunmap_atomic(ptr, KM_USER1);
    +
    + return 0;
    +}
    +
    +/**
    + * cr_read_pages_contents - read in data of pages in page-array chain
    + * @ctx - restart context
    + */
    +static int cr_read_pages_contents(struct cr_ctx *ctx)
    +{
    + struct mm_struct *mm = current->mm;
    + struct cr_pgarr *pgarr;
    + unsigned long *vaddrs;
    + char *buf;
    + int i, ret = 0;
    +
    + buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
    + if (!buf)
    + return -ENOMEM;
    +
    + down_read(&mm->mmap_sem);
    + list_for_each_entry_reverse(pgarr, &ctx->pgarr_list, list) {
    + vaddrs = pgarr->vaddrs;
    + for (i = 0; i < pgarr->nr_used; i++) {
    + struct page *page;
    +
    + ret = get_user_pages(current, mm, vaddrs[i],
    + 1, 1, 1, &page, NULL);
    + if (ret < 0)
    + goto out;
    +
    + ret = cr_page_read(ctx, page, buf);
    + page_cache_release(page);
    +
    + if (ret < 0)
    + goto out;
    + }
    + }
    +
    + out:
    + up_read(&mm->mmap_sem);
    + kfree(buf);
    + return 0;
    +}
    +
    +/**
    + * cr_read_private_vma_contents - restore contents of a VMA with private memory
    + * @ctx - restart context
    + *
    + * Reads a header that specifies how many pages will follow, then reads
    + * a list of virtual addresses into ctx->pgarr_list page-array chain,
    + * followed by the actual contents of the corresponding pages. Iterates
    + * these steps until reaching a header specifying "0" pages, which marks
    + * the end of the contents.
    + */
    +static int cr_read_private_vma_contents(struct cr_ctx *ctx)
    +{
    + struct cr_hdr_pgarr *hh;
    + unsigned long nr_pages;
    + int parent, ret = 0;
    +
    + while (1) {
    + hh = cr_hbuf_get(ctx, sizeof(*hh));
    + parent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_PGARR);
    + if (parent != 0) {
    + if (parent < 0)
    + ret = parent;
    + else
    + ret = -EINVAL;
    + cr_hbuf_put(ctx, sizeof(*hh));
    + break;
    + }
    +
    + cr_debug("nr_pages %ld\n", (unsigned long) hh->nr_pages);
    +
    + nr_pages = hh->nr_pages;
    + cr_hbuf_put(ctx, sizeof(*hh));
    +
    + if (!nr_pages)
    + break;
    +
    + ret = cr_read_pages_vaddrs(ctx, nr_pages);
    + if (ret < 0)
    + break;
    + ret = cr_read_pages_contents(ctx);
    + if (ret < 0)
    + break;
    + cr_pgarr_reset_all(ctx);
    + }
    +
    + return ret;
    +}
    +
    +/**
    + * cr_calc_map_prot_bits - convert vm_flags to mmap protection
    + * orig_vm_flags: source vm_flags
    + */
    +static unsigned long cr_calc_map_prot_bits(unsigned long orig_vm_flags)
    +{
    + unsigned long vm_prot = 0;
    +
    + if (orig_vm_flags & VM_READ)
    + vm_prot |= PROT_READ;
    + if (orig_vm_flags & VM_WRITE)
    + vm_prot |= PROT_WRITE;
    + if (orig_vm_flags & VM_EXEC)
    + vm_prot |= PROT_EXEC;
    + if (orig_vm_flags & PROT_SEM) /* only (?) with IPC-SHM */
    + vm_prot |= PROT_SEM;
    +
    + return vm_prot;
    +}
    +
    +/**
    + * cr_calc_map_flags_bits - convert vm_flags to mmap flags
    + * orig_vm_flags: source vm_flags
    + */
    +static unsigned long cr_calc_map_flags_bits(unsigned long orig_vm_flags)
    +{
    + unsigned long vm_flags = 0;
    +
    + vm_flags = MAP_FIXED;
    + if (orig_vm_flags & VM_GROWSDOWN)
    + vm_flags |= MAP_GROWSDOWN;
    + if (orig_vm_flags & VM_DENYWRITE)
    + vm_flags |= MAP_DENYWRITE;
    + if (orig_vm_flags & VM_EXECUTABLE)
    + vm_flags |= MAP_EXECUTABLE;
    + if (orig_vm_flags & VM_MAYSHARE)
    + vm_flags |= MAP_SHARED;
    + else
    + vm_flags |= MAP_PRIVATE;
    +
    + return vm_flags;
    +}
    +
    +static int cr_read_vma(struct cr_ctx *ctx, struct mm_struct *mm)
    +{
    + struct cr_hdr_vma *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + unsigned long vm_size, vm_start, vm_flags, vm_prot, vm_pgoff;
    + unsigned long addr;
    + struct file *file = NULL;
    + int parent, ret = -EINVAL;
    +
    + parent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_VMA);
    + if (parent < 0) {
    + ret = parent;
    + goto err;
    + } else if (parent != 0)
    + goto err;
    +
    + cr_debug("vma %#lx-%#lx type %d\n", (unsigned long) hh->vm_start,
    + (unsigned long) hh->vm_end, (int) hh->vma_type);
    +
    + if (hh->vm_end < hh->vm_start)
    + goto err;
    +
    + vm_start = hh->vm_start;
    + vm_pgoff = hh->vm_pgoff;
    + vm_size = hh->vm_end - hh->vm_start;
    + vm_prot = cr_calc_map_prot_bits(hh->vm_flags);
    + vm_flags = cr_calc_map_flags_bits(hh->vm_flags);
    +
    + switch (hh->vma_type) {
    +
    + case CR_VMA_ANON: /* anonymous private mapping */
    + if (vm_flags & VM_SHARED)
    + goto err;
    + /*
    + * vm_pgoff for anonymous mapping is the "global" page
    + * offset (namely from addr 0x0), so we force a zero
    + */
    + vm_pgoff = 0;
    + break;
    +
    + case CR_VMA_FILE: /* private mapping from a file */
    + if (vm_flags & VM_SHARED)
    + goto err;
    + /*
    + * for private mapping using 'read-only' is sufficient
    + */
    + file = cr_read_open_fname(ctx, O_RDONLY, 0);
    + if (IS_ERR(file)) {
    + ret = PTR_ERR(file);
    + goto err;
    + }
    + break;
    +
    + default:
    + goto err;
    +
    + }
    +
    + cr_hbuf_put(ctx, sizeof(*hh));
    +
    + down_write(&mm->mmap_sem);
    + addr = do_mmap_pgoff(file, vm_start, vm_size,
    + vm_prot, vm_flags, vm_pgoff);
    + up_write(&mm->mmap_sem);
    + cr_debug("size %#lx prot %#lx flag %#lx pgoff %#lx => %#lx\n",
    + vm_size, vm_prot, vm_flags, vm_pgoff, addr);
    +
    + /* the file (if opened) is now referenced by the vma */
    + if (file)
    + filp_close(file, NULL);
    +
    + if (IS_ERR((void *) addr))
    + return PTR_ERR((void *) addr);
    +
    + /*
    + * CR_VMA_ANON: read in memory as is
    + * CR_VMA_FILE: read in memory as is
    + * (more to follow ...)
    + */
    +
    + switch (hh->vma_type) {
    + case CR_VMA_ANON:
    + case CR_VMA_FILE:
    + /* standard case: read the data into the memory */
    + ret = cr_read_private_vma_contents(ctx);
    + break;
    + }
    +
    + if (ret < 0)
    + return ret;
    +
    + cr_debug("vma retval %d\n", ret);
    + return 0;
    +
    + err:
    + cr_hbuf_put(ctx, sizeof(*hh));
    + return ret;
    +}
    +
    +static int cr_destroy_mm(struct mm_struct *mm)
    +{
    + struct vm_area_struct *vmnext = mm->mmap;
    + struct vm_area_struct *vma;
    + int ret;
    +
    + while (vmnext) {
    + vma = vmnext;
    + vmnext = vmnext->vm_next;
    + ret = do_munmap(mm, vma->vm_start, vma->vm_end-vma->vm_start);
    + if (ret < 0) {
    + pr_debug("c/r: restart failed do_munmap (%d)\n", ret);
    + return ret;
    + }
    + }
    + return 0;
    +}
    +
    +int cr_read_mm(struct cr_ctx *ctx)
    +{
    + struct cr_hdr_mm *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + struct mm_struct *mm;
    + int nr, parent, ret;
    +
    + parent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_MM);
    + if (parent < 0) {
    + ret = parent;
    + goto out;
    + }
    +
    + ret = -EINVAL;
    +#if 0 /* activate when containers are used */
    + if (parent != task_pid_vnr(current))
    + goto out;
    +#endif
    + cr_debug("map_count %d\n", hh->map_count);
    +
    + /* XXX need more sanity checks */
    + if (hh->start_code > hh->end_code ||
    + hh->start_data > hh->end_data || hh->map_count < 0)
    + goto out;
    +
    + mm = current->mm;
    +
    + /* point of no return -- destruct current mm */
    + down_write(&mm->mmap_sem);
    + ret = cr_destroy_mm(mm);
    + if (ret < 0) {
    + up_write(&mm->mmap_sem);
    + goto out;
    + }
    + mm->start_code = hh->start_code;
    + mm->end_code = hh->end_code;
    + mm->start_data = hh->start_data;
    + mm->end_data = hh->end_data;
    + mm->start_brk = hh->start_brk;
    + mm->brk = hh->brk;
    + mm->start_stack = hh->start_stack;
    + mm->arg_start = hh->arg_start;
    + mm->arg_end = hh->arg_end;
    + mm->env_start = hh->env_start;
    + mm->env_end = hh->env_end;
    + up_write(&mm->mmap_sem);
    +
    + /* FIX: need also mm->flags */
    +
    + for (nr = hh->map_count; nr; nr--) {
    + ret = cr_read_vma(ctx, mm);
    + if (ret < 0)
    + goto out;
    + }
    +
    + ret = cr_read_mm_context(ctx, mm, hh->objref);
    + out:
    + cr_hbuf_put(ctx, sizeof(*hh));
    + return ret;
    +}
    diff --git a/include/linux/checkpoint.h b/include/linux/checkpoint.h
    index 7786e9b..56f5fef 100644
    --- a/include/linux/checkpoint.h
    +++ b/include/linux/checkpoint.h
    @@ -54,6 +54,9 @@ extern int cr_write_fname(struct cr_ctx *ctx,
    extern int cr_read_obj(struct cr_ctx *ctx, struct cr_hdr *h, void *buf, int n);
    extern int cr_read_obj_type(struct cr_ctx *ctx, void *buf, int n, int type);
    extern int cr_read_string(struct cr_ctx *ctx, void *str, int len);
    +extern int cr_read_fname(struct cr_ctx *ctx, void *fname, int n);
    +extern struct file *cr_read_open_fname(struct cr_ctx *ctx,
    + int flags, int mode);

    extern int do_checkpoint(struct cr_ctx *ctx, pid_t pid);
    extern int cr_write_mm(struct cr_ctx *ctx, struct task_struct *t);
    --
    1.5.4.3

    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

  6. [RFC v9][PATCH 01/13] Create syscalls: sys_checkpoint, sys_restart

    Create trivial sys_checkpoint and sys_restore system calls. They will
    enable to checkpoint and restart an entire container, to and from a
    checkpoint image file descriptor.

    The syscalls take a file descriptor (for the image file) and flags as
    arguments. For sys_checkpoint the first argument identifies the target
    container; for sys_restart it will identify the checkpoint image.

    A checkpoint, much like a process coredump, dumps the state of multiple
    processes at once, including the state of the container. The checkpoint
    image is written to (and read from) the file descriptor directly from
    the kernel. This way the data is generated and then pushed out naturally
    as resources and tasks are scanned to save their state. This is the
    approach taken by, e.g., Zap and OpenVZ.

    By using a return value and not a file descriptor, we can distinguish
    between a return from checkpoint, a return from restart (in case of a
    checkpoint that includes self, i.e. a task checkpointing its own
    container, or itself), and an error condition, in a manner analogous
    to a fork() call.

    We don't use copyin()/copyout() because it requires holding the entire
    image in user space, and does not make sense for restart. Also, we
    don't use a pipe, pseudo-fs file and the like, because they work by
    generating data on demand as the user pulls it (unless the entire
    image is buffered in the kernel) and would require more complex logic.
    They also would significantly complicate checkpoint that includes self.

    Changelog[v5]:
    - Config is 'def_bool n' by default

    Signed-off-by: Oren Laadan
    Acked-by: Serge Hallyn
    Signed-off-by: Dave Hansen
    ---
    arch/x86/include/asm/unistd_32.h | 2 +
    arch/x86/kernel/syscall_table_32.S | 2 +
    checkpoint/Kconfig | 11 +++++++++
    checkpoint/Makefile | 5 ++++
    checkpoint/sys.c | 41 ++++++++++++++++++++++++++++++++++++
    include/linux/syscalls.h | 2 +
    init/Kconfig | 2 +
    kernel/sys_ni.c | 4 +++
    8 files changed, 69 insertions(+), 0 deletions(-)
    create mode 100644 checkpoint/Kconfig
    create mode 100644 checkpoint/Makefile
    create mode 100644 checkpoint/sys.c

    diff --git a/arch/x86/include/asm/unistd_32.h b/arch/x86/include/asm/unistd_32.h
    index f2bba78..a5f9e09 100644
    --- a/arch/x86/include/asm/unistd_32.h
    +++ b/arch/x86/include/asm/unistd_32.h
    @@ -338,6 +338,8 @@
    #define __NR_dup3 330
    #define __NR_pipe2 331
    #define __NR_inotify_init1 332
    +#define __NR_checkpoint 333
    +#define __NR_restart 334

    #ifdef __KERNEL__

    diff --git a/arch/x86/kernel/syscall_table_32.S b/arch/x86/kernel/syscall_table_32.S
    index d44395f..5543136 100644
    --- a/arch/x86/kernel/syscall_table_32.S
    +++ b/arch/x86/kernel/syscall_table_32.S
    @@ -332,3 +332,5 @@ ENTRY(sys_call_table)
    .long sys_dup3 /* 330 */
    .long sys_pipe2
    .long sys_inotify_init1
    + .long sys_checkpoint
    + .long sys_restart
    diff --git a/checkpoint/Kconfig b/checkpoint/Kconfig
    new file mode 100644
    index 0000000..ffaa635
    --- /dev/null
    +++ b/checkpoint/Kconfig
    @@ -0,0 +1,11 @@
    +config CHECKPOINT_RESTART
    + prompt "Enable checkpoint/restart (EXPERIMENTAL)"
    + def_bool n
    + depends on X86_32 && EXPERIMENTAL
    + help
    + Application checkpoint/restart is the ability to save the
    + state of a running application so that it can later resume
    + its execution from the time at which it was checkpointed.
    +
    + Turning this option on will enable checkpoint and restart
    + functionality in the kernel.
    diff --git a/checkpoint/Makefile b/checkpoint/Makefile
    new file mode 100644
    index 0000000..07d018b
    --- /dev/null
    +++ b/checkpoint/Makefile
    @@ -0,0 +1,5 @@
    +#
    +# Makefile for linux checkpoint/restart.
    +#
    +
    +obj-$(CONFIG_CHECKPOINT_RESTART) += sys.o
    diff --git a/checkpoint/sys.c b/checkpoint/sys.c
    new file mode 100644
    index 0000000..375129c
    --- /dev/null
    +++ b/checkpoint/sys.c
    @@ -0,0 +1,41 @@
    +/*
    + * Generic container checkpoint-restart
    + *
    + * Copyright (C) 2008 Oren Laadan
    + *
    + * This file is subject to the terms and conditions of the GNU General Public
    + * License. See the file COPYING in the main directory of the Linux
    + * distribution for more details.
    + */
    +
    +#include
    +#include
    +
    +/**
    + * sys_checkpoint - checkpoint a container
    + * @pid: pid of the container init(1) process
    + * @fd: file to which dump the checkpoint image
    + * @flags: checkpoint operation flags
    + *
    + * Returns positive identifier on success, 0 when returning from restart
    + * or negative value on error
    + */
    +asmlinkage long sys_checkpoint(pid_t pid, int fd, unsigned long flags)
    +{
    + pr_debug("sys_checkpoint not implemented yet\n");
    + return -ENOSYS;
    +}
    +/**
    + * sys_restart - restart a container
    + * @crid: checkpoint image identifier
    + * @fd: file from which read the checkpoint image
    + * @flags: restart operation flags
    + *
    + * Returns negative value on error, or otherwise returns in the realm
    + * of the original checkpoint
    + */
    +asmlinkage long sys_restart(int crid, int fd, unsigned long flags)
    +{
    + pr_debug("sys_restart not implemented yet\n");
    + return -ENOSYS;
    +}
    diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
    index d6ff145..edc218b 100644
    --- a/include/linux/syscalls.h
    +++ b/include/linux/syscalls.h
    @@ -622,6 +622,8 @@ asmlinkage long sys_timerfd_gettime(int ufd, struct itimerspec __user *otmr);
    asmlinkage long sys_eventfd(unsigned int count);
    asmlinkage long sys_eventfd2(unsigned int count, int flags);
    asmlinkage long sys_fallocate(int fd, int mode, loff_t offset, loff_t len);
    +asmlinkage long sys_checkpoint(pid_t pid, int fd, unsigned long flags);
    +asmlinkage long sys_restart(int crid, int fd, unsigned long flags);

    int kernel_execve(const char *filename, char *const argv[], char *const envp[]);

    diff --git a/init/Kconfig b/init/Kconfig
    index 86b00c5..743e2ad 100644
    --- a/init/Kconfig
    +++ b/init/Kconfig
    @@ -814,6 +814,8 @@ config MARKERS

    source "arch/Kconfig"

    +source "checkpoint/Kconfig"
    +
    endmenu # General setup

    config HAVE_GENERIC_DMA_COHERENT
    diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
    index a77b27b..e4e289e 100644
    --- a/kernel/sys_ni.c
    +++ b/kernel/sys_ni.c
    @@ -174,3 +174,7 @@ cond_syscall(compat_sys_timerfd_settime);
    cond_syscall(compat_sys_timerfd_gettime);
    cond_syscall(sys_eventfd);
    cond_syscall(sys_eventfd2);
    +
    +/* checkpoint/restart */
    +cond_syscall(sys_checkpoint);
    +cond_syscall(sys_restart);
    --
    1.5.4.3

    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

  7. [RFC v9][PATCH 08/13] Dump open file descriptors

    Dump the files_struct of a task with 'struct cr_hdr_files', followed by
    all open file descriptors. Since FDs can be shared, they are assigned an
    objref and registered in the object hash.

    For each open FD there is a 'struct cr_hdr_fd_ent' with the FD, its objref
    and its close-on-exec property. If the FD is to be saved (first time)
    then this is followed by a 'struct cr_hdr_fd_data' with the FD state.
    Then will come the next FD and so on.

    This patch only handles basic FDs - regular files, directories and also
    symbolic links.

    Changelog[v9]:
    - Fix a couple of leaks in cr_write_files()
    - Drop useless kfree from cr_scan_fds()

    Changelog[v8]:
    - initialize 'coe' to workaround gcc false warning

    Changelog[v6]:
    - Balance all calls to cr_hbuf_get() with matching cr_hbuf_put()
    (even though it's not really needed)

    Signed-off-by: Oren Laadan
    Acked-by: Serge Hallyn
    Signed-off-by: Dave Hansen
    ---
    checkpoint/Makefile | 2 +-
    checkpoint/checkpoint.c | 4 +
    checkpoint/checkpoint_file.h | 17 +++
    checkpoint/ckpt_file.c | 231 ++++++++++++++++++++++++++++++++++++++++
    include/linux/checkpoint.h | 3 +-
    include/linux/checkpoint_hdr.h | 32 ++++++-
    6 files changed, 286 insertions(+), 3 deletions(-)
    create mode 100644 checkpoint/checkpoint_file.h
    create mode 100644 checkpoint/ckpt_file.c

    diff --git a/checkpoint/Makefile b/checkpoint/Makefile
    index 9843fb9..7496695 100644
    --- a/checkpoint/Makefile
    +++ b/checkpoint/Makefile
    @@ -3,4 +3,4 @@
    #

    obj-$(CONFIG_CHECKPOINT_RESTART) += sys.o checkpoint.o restart.o objhash.o \
    - ckpt_mem.o rstr_mem.o
    + ckpt_mem.o rstr_mem.o ckpt_file.o
    diff --git a/checkpoint/checkpoint.c b/checkpoint/checkpoint.c
    index e162753..700f829 100644
    --- a/checkpoint/checkpoint.c
    +++ b/checkpoint/checkpoint.c
    @@ -213,6 +213,10 @@ static int cr_write_task(struct cr_ctx *ctx, struct task_struct *t)
    cr_debug("memory: ret %d\n", ret);
    if (ret < 0)
    goto out;
    + ret = cr_write_files(ctx, t);
    + cr_debug("files: ret %d\n", ret);
    + if (ret < 0)
    + goto out;
    ret = cr_write_thread(ctx, t);
    cr_debug("thread: ret %d\n", ret);
    if (ret < 0)
    diff --git a/checkpoint/checkpoint_file.h b/checkpoint/checkpoint_file.h
    new file mode 100644
    index 0000000..9dc3eba
    --- /dev/null
    +++ b/checkpoint/checkpoint_file.h
    @@ -0,0 +1,17 @@
    +#ifndef _CHECKPOINT_CKPT_FILE_H_
    +#define _CHECKPOINT_CKPT_FILE_H_
    +/*
    + * Checkpoint file descriptors
    + *
    + * Copyright (C) 2008 Oren Laadan
    + *
    + * This file is subject to the terms and conditions of the GNU General Public
    + * License. See the file COPYING in the main directory of the Linux
    + * distribution for more details.
    + */
    +
    +#include
    +
    +int cr_scan_fds(struct files_struct *files, int **fdtable);
    +
    +#endif /* _CHECKPOINT_CKPT_FILE_H_ */
    diff --git a/checkpoint/ckpt_file.c b/checkpoint/ckpt_file.c
    new file mode 100644
    index 0000000..9198650
    --- /dev/null
    +++ b/checkpoint/ckpt_file.c
    @@ -0,0 +1,231 @@
    +/*
    + * Checkpoint file descriptors
    + *
    + * Copyright (C) 2008 Oren Laadan
    + *
    + * This file is subject to the terms and conditions of the GNU General Public
    + * License. See the file COPYING in the main directory of the Linux
    + * distribution for more details.
    + */
    +
    +#include
    +#include
    +#include
    +#include
    +#include
    +#include
    +
    +#include "checkpoint_file.h"
    +
    +#define CR_DEFAULT_FDTABLE 256 /* an initial guess */
    +
    +/**
    + * cr_scan_fds - scan file table and construct array of open fds
    + * @files: files_struct pointer
    + * @fdtable: (output) array of open fds
    + *
    + * Returns the number of open fds found, and also the file table
    + * array via *fdtable. The caller should free the array.
    + *
    + * The caller must validate the file descriptors collected in the
    + * array before using them, e.g. by using fcheck_files(), in case
    + * the task's fdtable changes in the meantime.
    + */
    +int cr_scan_fds(struct files_struct *files, int **fdtable)
    +{
    + struct fdtable *fdt;
    + int *fds;
    + int i, n = 0;
    + int tot = CR_DEFAULT_FDTABLE;
    +
    + fds = kmalloc(tot * sizeof(*fds), GFP_KERNEL);
    + if (!fds)
    + return -ENOMEM;
    +
    + /*
    + * We assume that the target task is frozen (or that we checkpoint
    + * ourselves), so we can safely proceed after krealloc() from where
    + * we left off; in the worst cases restart will fail.
    + */
    +
    + spin_lock(&files->file_lock);
    + rcu_read_lock();
    + fdt = files_fdtable(files);
    + for (i = 0; i < fdt->max_fds; i++) {
    + if (!fcheck_files(files, i))
    + continue;
    + if (n == tot) {
    + /*
    + * fcheck_files() is safe with drop/re-acquire
    + * of the lock, because it tests: fd < max_fds
    + */
    + spin_unlock(&files->file_lock);
    + rcu_read_unlock();
    + tot *= 2; /* won't overflow: kmalloc will fail */
    + fds = krealloc(fds, tot * sizeof(*fds), GFP_KERNEL);
    + if (!fds)
    + return -ENOMEM;
    + rcu_read_lock();
    + spin_lock(&files->file_lock);
    + }
    + fds[n++] = i;
    + }
    + rcu_read_unlock();
    + spin_unlock(&files->file_lock);
    +
    + *fdtable = fds;
    + return n;
    +}
    +
    +/* cr_write_fd_data - dump the state of a given file pointer */
    +static int cr_write_fd_data(struct cr_ctx *ctx, struct file *file, int parent)
    +{
    + struct cr_hdr h;
    + struct cr_hdr_fd_data *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + struct dentry *dent = file->f_dentry;
    + struct inode *inode = dent->d_inode;
    + enum fd_type fd_type;
    + int ret;
    +
    + h.type = CR_HDR_FD_DATA;
    + h.len = sizeof(*hh);
    + h.parent = parent;
    +
    + hh->f_flags = file->f_flags;
    + hh->f_mode = file->f_mode;
    + hh->f_pos = file->f_pos;
    + hh->f_version = file->f_version;
    + /* FIX: need also file->uid, file->gid, file->f_owner, etc */
    +
    + switch (inode->i_mode & S_IFMT) {
    + case S_IFREG:
    + fd_type = CR_FD_FILE;
    + break;
    + case S_IFDIR:
    + fd_type = CR_FD_DIR;
    + break;
    + case S_IFLNK:
    + fd_type = CR_FD_LINK;
    + break;
    + default:
    + cr_hbuf_put(ctx, sizeof(*hh));
    + return -EBADF;
    + }
    +
    + /* FIX: check if the file/dir/link is unlinked */
    + hh->fd_type = fd_type;
    +
    + ret = cr_write_obj(ctx, &h, hh);
    + cr_hbuf_put(ctx, sizeof(*hh));
    + if (ret < 0)
    + return ret;
    +
    + return cr_write_fname(ctx, &file->f_path, ctx->vfsroot);
    +}
    +
    +/**
    + * cr_write_fd_ent - dump the state of a given file descriptor
    + * @ctx: checkpoint context
    + * @files: files_struct pointer
    + * @fd: file descriptor
    + *
    + * Saves the state of the file descriptor; looks up the actual file
    + * pointer in the hash table, and if found saves the matching objref,
    + * otherwise calls cr_write_fd_data to dump the file pointer too.
    + */
    +static int
    +cr_write_fd_ent(struct cr_ctx *ctx, struct files_struct *files, int fd)
    +{
    + struct cr_hdr h;
    + struct cr_hdr_fd_ent *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + struct file *file;
    + struct fdtable *fdt;
    + int objref, new, ret;
    + int coe = 0; /* avoid gcc warning */
    +
    + rcu_read_lock();
    + fdt = files_fdtable(files);
    + file = fcheck_files(files, fd);
    + if (file) {
    + coe = FD_ISSET(fd, fdt->close_on_exec);
    + get_file(file);
    + }
    + rcu_read_unlock();
    +
    + /* sanity check (although this shouldn't happen) */
    + if (!file) {
    + ret = -EBADF;
    + goto out;
    + }
    +
    + new = cr_obj_add_ptr(ctx, file, &objref, CR_OBJ_FILE, 0);
    + cr_debug("fd %d objref %d file %p c-o-e %d)\n", fd, objref, file, coe);
    +
    + if (new < 0) {
    + ret = new;
    + goto out;
    + }
    +
    + h.type = CR_HDR_FD_ENT;
    + h.len = sizeof(*hh);
    + h.parent = 0;
    +
    + hh->objref = objref;
    + hh->fd = fd;
    + hh->close_on_exec = coe;
    +
    + ret = cr_write_obj(ctx, &h, hh);
    + if (ret < 0)
    + goto out;
    +
    + /* new==1 if-and-only-if file was newly added to hash */
    + if (new)
    + ret = cr_write_fd_data(ctx, file, objref);
    +
    +out:
    + cr_hbuf_put(ctx, sizeof(*hh));
    + if (file)
    + fput(file);
    + return ret;
    +}
    +
    +int cr_write_files(struct cr_ctx *ctx, struct task_struct *t)
    +{
    + struct cr_hdr h;
    + struct cr_hdr_files *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + struct files_struct *files;
    + int *fdtable = NULL;
    + int nfds, n, ret;
    +
    + h.type = CR_HDR_FILES;
    + h.len = sizeof(*hh);
    + h.parent = task_pid_vnr(t);
    +
    + files = get_files_struct(t);
    +
    + nfds = cr_scan_fds(files, &fdtable);
    + if (nfds < 0) {
    + ret = nfds;
    + goto out;
    + }
    +
    + hh->objref = 0; /* will be meaningful with multiple processes */
    + hh->nfds = nfds;
    +
    + ret = cr_write_obj(ctx, &h, hh);
    + cr_hbuf_put(ctx, sizeof(*hh));
    + if (ret < 0)
    + goto out;
    +
    + cr_debug("nfds %d\n", nfds);
    + for (n = 0; n < nfds; n++) {
    + ret = cr_write_fd_ent(ctx, files, fdtable[n]);
    + if (ret < 0)
    + break;
    + }
    +
    + out:
    + kfree(fdtable);
    + put_files_struct(files);
    + return ret;
    +}
    diff --git a/include/linux/checkpoint.h b/include/linux/checkpoint.h
    index 0e4ba74..bca7aef 100644
    --- a/include/linux/checkpoint.h
    +++ b/include/linux/checkpoint.h
    @@ -13,7 +13,7 @@
    #include
    #include

    -#define CR_VERSION 1
    +#define CR_VERSION 2

    struct cr_ctx {
    int crid; /* unique checkpoint id */
    @@ -80,6 +80,7 @@ extern struct file *cr_read_open_fname(struct cr_ctx *ctx,

    extern int do_checkpoint(struct cr_ctx *ctx, pid_t pid);
    extern int cr_write_mm(struct cr_ctx *ctx, struct task_struct *t);
    +extern int cr_write_files(struct cr_ctx *ctx, struct task_struct *t);

    extern int do_restart(struct cr_ctx *ctx, pid_t pid);
    extern int cr_read_mm(struct cr_ctx *ctx);
    diff --git a/include/linux/checkpoint_hdr.h b/include/linux/checkpoint_hdr.h
    index c2e1022..3a21179 100644
    --- a/include/linux/checkpoint_hdr.h
    +++ b/include/linux/checkpoint_hdr.h
    @@ -17,7 +17,7 @@
    /*
    * To maintain compatibility between 32-bit and 64-bit architecture flavors,
    * keep data 64-bit aligned: use padding for structure members, and use
    - * __attribute__ ((aligned (8))) for the entire structure.
    + * __attribute__((aligned(8))) for the entire structure.
    */

    /* records: generic header */
    @@ -44,6 +44,10 @@ enum {
    CR_HDR_PGARR,
    CR_HDR_MM_CONTEXT,

    + CR_HDR_FILES = 301,
    + CR_HDR_FD_ENT,
    + CR_HDR_FD_DATA,
    +
    CR_HDR_TAIL = 5001
    };

    @@ -106,4 +110,30 @@ struct cr_hdr_pgarr {
    __u64 nr_pages; /* number of pages to saved */
    } __attribute__((aligned(8)));

    +struct cr_hdr_files {
    + __u32 objref; /* identifier for shared objects */
    + __u32 nfds;
    +} __attribute__((aligned(8)));
    +
    +struct cr_hdr_fd_ent {
    + __u32 objref; /* identifier for shared objects */
    + __s32 fd;
    + __u32 close_on_exec;
    +} __attribute__((aligned(8)));
    +
    +/* fd types */
    +enum fd_type {
    + CR_FD_FILE = 1,
    + CR_FD_DIR,
    + CR_FD_LINK
    +};
    +
    +struct cr_hdr_fd_data {
    + __u16 fd_type;
    + __u16 f_mode;
    + __u32 f_flags;
    + __u64 f_pos;
    + __u64 f_version;
    +} __attribute__((aligned(8)));
    +
    #endif /* _CHECKPOINT_CKPT_HDR_H_ */
    --
    1.5.4.3

    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

  8. [RFC v9][PATCH 04/13] x86 support for checkpoint/restart

    Add logic to save and restore architecture specific state, including
    thread-specific state, CPU registers and FPU state.

    In addition, architecture capabilities are saved in an architecure
    specific extension of the header (cr_hdr_head_arch); Currently this
    includes only FPU capabilities.

    Currently only x86-32 is supported. Compiling on x86-64 will trigger
    an explicit error.

    Changelog[v9]:
    - Add arch-specific header that details architecture capabilities;
    split FPU restore to send capabilities only once.
    - Test for zero TLS entries in cr_write_thread()
    - Fix asm/checkpoint_hdr.h so it can be included from user-space

    Changelog[v7]:
    - Fix save/restore state of FPU

    Changelog[v5]:
    - Remove preempt_disable() when restoring debug registers

    Changelog[v4]:
    - Fix header structure alignment

    Changelog[v2]:
    - Pad header structures to 64 bits to ensure compatibility
    - Follow Dave Hansen's refactoring of the original post

    Signed-off-by: Oren Laadan
    Acked-by: Serge Hallyn
    Signed-off-by: Dave Hansen
    ---
    arch/x86/include/asm/checkpoint_hdr.h | 85 ++++++++++++
    arch/x86/mm/Makefile | 2 +
    arch/x86/mm/checkpoint.c | 223 +++++++++++++++++++++++++++++++
    arch/x86/mm/restart.c | 232 +++++++++++++++++++++++++++++++++
    checkpoint/checkpoint.c | 19 +++-
    checkpoint/checkpoint_arch.h | 9 ++
    checkpoint/restart.c | 17 ++-
    include/linux/checkpoint_hdr.h | 2 +
    8 files changed, 583 insertions(+), 6 deletions(-)
    create mode 100644 arch/x86/include/asm/checkpoint_hdr.h
    create mode 100644 arch/x86/mm/checkpoint.c
    create mode 100644 arch/x86/mm/restart.c
    create mode 100644 checkpoint/checkpoint_arch.h

    diff --git a/arch/x86/include/asm/checkpoint_hdr.h b/arch/x86/include/asm/checkpoint_hdr.h
    new file mode 100644
    index 0000000..6325062
    --- /dev/null
    +++ b/arch/x86/include/asm/checkpoint_hdr.h
    @@ -0,0 +1,85 @@
    +#ifndef __ASM_X86_CKPT_HDR_H
    +#define __ASM_X86_CKPT_HDR_H
    +/*
    + * Checkpoint/restart - architecture specific headers x86
    + *
    + * Copyright (C) 2008 Oren Laadan
    + *
    + * This file is subject to the terms and conditions of the GNU General Public
    + * License. See the file COPYING in the main directory of the Linux
    + * distribution for more details.
    + */
    +
    +#include
    +
    +/* i387 structure seen from kernel/userspace */
    +#ifdef __KERNEL__
    +#include
    +#else
    +#include
    +#endif
    +
    +struct cr_hdr_head_arch {
    + /* FIXME: add HAVE_HWFP */
    +
    + __u16 has_fxsr;
    + __u16 has_xsave;
    + __u16 xstate_size;
    + __u16 _pading;
    +} __attribute__((aligned(8)));
    +
    +struct cr_hdr_thread {
    + /* FIXME: restart blocks */
    +
    + __s16 gdt_entry_tls_entries;
    + __s16 sizeof_tls_array;
    + __s16 ntls; /* number of TLS entries to follow */
    +} __attribute__((aligned(8)));
    +
    +struct cr_hdr_cpu {
    + /* see struct pt_regs (x86-64) */
    + __u64 r15;
    + __u64 r14;
    + __u64 r13;
    + __u64 r12;
    + __u64 bp;
    + __u64 bx;
    + __u64 r11;
    + __u64 r10;
    + __u64 r9;
    + __u64 r8;
    + __u64 ax;
    + __u64 cx;
    + __u64 dx;
    + __u64 si;
    + __u64 di;
    + __u64 orig_ax;
    + __u64 ip;
    + __u64 cs;
    + __u64 flags;
    + __u64 sp;
    + __u64 ss;
    +
    + /* segment registers */
    + __u64 ds;
    + __u64 es;
    + __u64 fs;
    + __u64 gs;
    +
    + /* debug registers */
    + __u64 debugreg0;
    + __u64 debugreg1;
    + __u64 debugreg2;
    + __u64 debugreg3;
    + __u64 debugreg4;
    + __u64 debugreg5;
    + __u64 debugreg6;
    + __u64 debugreg7;
    +
    + __u32 uses_debug;
    + __u32 used_math;
    +
    + /* thread_xstate contents follow (if used_math) */
    +} __attribute__((aligned(8)));
    +
    +#endif /* __ASM_X86_CKPT_HDR__H */
    diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile
    index 59f89b4..7d5e2ce 100644
    --- a/arch/x86/mm/Makefile
    +++ b/arch/x86/mm/Makefile
    @@ -18,3 +18,5 @@ obj-$(CONFIG_K8_NUMA) += k8topology_64.o
    obj-$(CONFIG_ACPI_NUMA) += srat_$(BITS).o

    obj-$(CONFIG_MEMTEST) += memtest.o
    +
    +obj-$(CONFIG_CHECKPOINT_RESTART) += checkpoint.o restart.o
    diff --git a/arch/x86/mm/checkpoint.c b/arch/x86/mm/checkpoint.c
    new file mode 100644
    index 0000000..8dd6d2d
    --- /dev/null
    +++ b/arch/x86/mm/checkpoint.c
    @@ -0,0 +1,223 @@
    +/*
    + * Checkpoint/restart - architecture specific support for x86
    + *
    + * Copyright (C) 2008 Oren Laadan
    + *
    + * This file is subject to the terms and conditions of the GNU General Public
    + * License. See the file COPYING in the main directory of the Linux
    + * distribution for more details.
    + */
    +
    +#include
    +#include
    +
    +#include
    +#include
    +
    +/* dump the thread_struct of a given task */
    +int cr_write_thread(struct cr_ctx *ctx, struct task_struct *t)
    +{
    + struct cr_hdr h;
    + struct cr_hdr_thread *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + struct thread_struct *thread;
    + struct desc_struct *desc;
    + int ntls = 0;
    + int n, ret;
    +
    + h.type = CR_HDR_THREAD;
    + h.len = sizeof(*hh);
    + h.parent = task_pid_vnr(t);
    +
    + thread = &t->thread;
    +
    + /* calculate no. of TLS entries that follow */
    + desc = thread->tls_array;
    + for (n = GDT_ENTRY_TLS_ENTRIES; n > 0; n--, desc++) {
    + if (desc->a || desc->b)
    + ntls++;
    + }
    +
    + hh->gdt_entry_tls_entries = GDT_ENTRY_TLS_ENTRIES;
    + hh->sizeof_tls_array = sizeof(thread->tls_array);
    + hh->ntls = ntls;
    +
    + ret = cr_write_obj(ctx, &h, hh);
    + cr_hbuf_put(ctx, sizeof(*hh));
    + if (ret < 0)
    + return ret;
    +
    + cr_debug("ntls %d\n", ntls);
    + if (ntls == 0)
    + return 0;
    +
    + /* for simplicity dump the entire array, cherry-pick upon restart */
    + ret = cr_kwrite(ctx, thread->tls_array, sizeof(thread->tls_array));
    +
    + /* IGNORE RESTART BLOCKS FOR NOW ... */
    +
    + return ret;
    +}
    +
    +#ifdef CONFIG_X86_64
    +
    +#error "CONFIG_X86_64 unsupported yet."
    +
    +#else /* !CONFIG_X86_64 */
    +
    +static void cr_save_cpu_regs(struct cr_hdr_cpu *hh, struct task_struct *t)
    +{
    + struct thread_struct *thread = &t->thread;
    + struct pt_regs *regs = task_pt_regs(t);
    +
    + hh->bp = regs->bp;
    + hh->bx = regs->bx;
    + hh->ax = regs->ax;
    + hh->cx = regs->cx;
    + hh->dx = regs->dx;
    + hh->si = regs->si;
    + hh->di = regs->di;
    + hh->orig_ax = regs->orig_ax;
    + hh->ip = regs->ip;
    + hh->cs = regs->cs;
    + hh->flags = regs->flags;
    + hh->sp = regs->sp;
    + hh->ss = regs->ss;
    +
    + hh->ds = regs->ds;
    + hh->es = regs->es;
    +
    + /*
    + * for checkpoint in process context (from within a container)
    + * the GS and FS registers should be saved from the hardware;
    + * otherwise they are already sabed on the thread structure
    + */
    + if (t == current) {
    + savesegment(gs, hh->gs);
    + savesegment(fs, hh->fs);
    + } else {
    + hh->gs = thread->gs;
    + hh->fs = thread->fs;
    + }
    +
    + /*
    + * for checkpoint in process context (from within a container),
    + * the actual syscall is taking place at this very moment; so
    + * we (optimistically) subtitute the future return value (0) of
    + * this syscall into the orig_eax, so that upon restart it will
    + * succeed (or it will endlessly retry checkpoint...)
    + */
    + if (t == current) {
    + BUG_ON(hh->orig_ax < 0);
    + hh->ax = 0;
    + }
    +}
    +
    +static void cr_save_cpu_debug(struct cr_hdr_cpu *hh, struct task_struct *t)
    +{
    + struct thread_struct *thread = &t->thread;
    +
    + /* debug regs */
    +
    + /*
    + * for checkpoint in process context (from within a container),
    + * get the actual registers; otherwise get the saved values.
    + */
    +
    + if (t == current) {
    + get_debugreg(hh->debugreg0, 0);
    + get_debugreg(hh->debugreg1, 1);
    + get_debugreg(hh->debugreg2, 2);
    + get_debugreg(hh->debugreg3, 3);
    + get_debugreg(hh->debugreg6, 6);
    + get_debugreg(hh->debugreg7, 7);
    + } else {
    + hh->debugreg0 = thread->debugreg0;
    + hh->debugreg1 = thread->debugreg1;
    + hh->debugreg2 = thread->debugreg2;
    + hh->debugreg3 = thread->debugreg3;
    + hh->debugreg6 = thread->debugreg6;
    + hh->debugreg7 = thread->debugreg7;
    + }
    +
    + hh->debugreg4 = 0;
    + hh->debugreg5 = 0;
    +
    + hh->uses_debug = !!(task_thread_info(t)->flags & TIF_DEBUG);
    +}
    +
    +static void cr_save_cpu_fpu(struct cr_hdr_cpu *hh, struct task_struct *t)
    +{
    + hh->used_math = tsk_used_math(t) ? 1 : 0;
    +}
    +
    +static int cr_write_cpu_fpu(struct cr_ctx *ctx, struct task_struct *t)
    +{
    + void *xstate_buf = cr_hbuf_get(ctx, xstate_size);
    +
    + /* i387 + MMU + SSE logic */
    + preempt_disable(); /* needed it (t == current) */
    +
    + /*
    + * normally, no need to unlazy_fpu(), since TS_USEDFPU flag
    + * have been cleared when task was context-switched out...
    + * except if we are in process context, in which case we do
    + */
    + if (t == current && (task_thread_info(t)->status & TS_USEDFPU))
    + unlazy_fpu(current);
    +
    + memcpy(xstate_buf, t->thread.xstate, xstate_size);
    + preempt_enable(); /* needed it (t == current) */
    +
    + return cr_kwrite(ctx, xstate_buf, xstate_size);
    +}
    +
    +#endif /* CONFIG_X86_64 */
    +
    +/* dump the cpu state and registers of a given task */
    +int cr_write_cpu(struct cr_ctx *ctx, struct task_struct *t)
    +{
    + struct cr_hdr h;
    + struct cr_hdr_cpu *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + int ret;
    +
    + h.type = CR_HDR_CPU;
    + h.len = sizeof(*hh);
    + h.parent = task_pid_vnr(t);
    +
    + cr_save_cpu_regs(hh, t);
    + cr_save_cpu_debug(hh, t);
    + cr_save_cpu_fpu(hh, t);
    +
    + cr_debug("math %d debug %d\n", hh->used_math, hh->uses_debug);
    +
    + ret = cr_write_obj(ctx, &h, hh);
    + if (ret < 0)
    + goto out;
    +
    + if (hh->used_math)
    + ret = cr_write_cpu_fpu(ctx, t);
    + out:
    + cr_hbuf_put(ctx, sizeof(*hh));
    + return ret;
    +}
    +
    +int cr_write_head_arch(struct cr_ctx *ctx)
    +{
    + struct cr_hdr h;
    + struct cr_hdr_head_arch *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + int ret;
    +
    + h.type = CR_HDR_HEAD_ARCH;
    + h.len = sizeof(*hh);
    + h.parent = 0;
    +
    + /* FPU capabilities */
    + hh->has_fxsr = cpu_has_fxsr;
    + hh->has_xsave = cpu_has_xsave;
    + hh->xstate_size = xstate_size;
    +
    + ret = cr_write_obj(ctx, &h, hh);
    + cr_hbuf_put(ctx, sizeof(*hh));
    +
    + return ret;
    +}
    diff --git a/arch/x86/mm/restart.c b/arch/x86/mm/restart.c
    new file mode 100644
    index 0000000..45ad790
    --- /dev/null
    +++ b/arch/x86/mm/restart.c
    @@ -0,0 +1,232 @@
    +/*
    + * Checkpoint/restart - architecture specific support for x86
    + *
    + * Copyright (C) 2008 Oren Laadan
    + *
    + * This file is subject to the terms and conditions of the GNU General Public
    + * License. See the file COPYING in the main directory of the Linux
    + * distribution for more details.
    + */
    +
    +#include
    +#include
    +
    +#include
    +#include
    +
    +/* read the thread_struct into the current task */
    +int cr_read_thread(struct cr_ctx *ctx)
    +{
    + struct cr_hdr_thread *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + struct task_struct *t = current;
    + struct thread_struct *thread = &t->thread;
    + int parent, ret;
    +
    + parent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_THREAD);
    + if (parent < 0) {
    + ret = parent;
    + goto out;
    + }
    +
    + ret = -EINVAL;
    +
    +#if 0 /* activate when containers are used */
    + if (parent != task_pid_vnr(t))
    + goto out;
    +#endif
    + cr_debug("ntls %d\n", hh->ntls);
    +
    + if (hh->gdt_entry_tls_entries != GDT_ENTRY_TLS_ENTRIES ||
    + hh->sizeof_tls_array != sizeof(thread->tls_array) ||
    + hh->ntls < 0 || hh->ntls > GDT_ENTRY_TLS_ENTRIES)
    + goto out;
    +
    + if (hh->ntls > 0) {
    + struct desc_struct *desc;
    + int size, cpu;
    +
    + /*
    + * restore TLS by hand: why convert to struct user_desc if
    + * sys_set_thread_entry() will convert it back ?
    + */
    +
    + size = sizeof(*desc) * GDT_ENTRY_TLS_ENTRIES;
    + desc = kmalloc(size, GFP_KERNEL);
    + if (!desc)
    + return -ENOMEM;
    +
    + ret = cr_kread(ctx, desc, size);
    + if (ret >= 0) {
    + /*
    + * FIX: add sanity checks (eg. that values makes
    + * sense, that we don't overwrite old values, etc
    + */
    + cpu = get_cpu();
    + memcpy(thread->tls_array, desc, size);
    + load_TLS(thread, cpu);
    + put_cpu();
    + }
    + kfree(desc);
    + }
    +
    + ret = 0;
    + out:
    + cr_hbuf_put(ctx, sizeof(*hh));
    + return ret;
    +}
    +
    +#ifdef CONFIG_X86_64
    +
    +#error "CONFIG_X86_64 unsupported yet."
    +
    +#else /* !CONFIG_X86_64 */
    +
    +static int cr_load_cpu_regs(struct cr_hdr_cpu *hh, struct task_struct *t)
    +{
    + struct thread_struct *thread = &t->thread;
    + struct pt_regs *regs = task_pt_regs(t);
    +
    + regs->bx = hh->bx;
    + regs->cx = hh->cx;
    + regs->dx = hh->dx;
    + regs->si = hh->si;
    + regs->di = hh->di;
    + regs->bp = hh->bp;
    + regs->ax = hh->ax;
    + regs->ds = hh->ds;
    + regs->es = hh->es;
    + regs->orig_ax = hh->orig_ax;
    + regs->ip = hh->ip;
    + regs->cs = hh->cs;
    + regs->flags = hh->flags;
    + regs->sp = hh->sp;
    + regs->ss = hh->ss;
    +
    + thread->gs = hh->gs;
    + thread->fs = hh->fs;
    + loadsegment(gs, hh->gs);
    + loadsegment(fs, hh->fs);
    +
    + return 0;
    +}
    +
    +static int cr_load_cpu_debug(struct cr_hdr_cpu *hh, struct task_struct *t)
    +{
    + /* debug regs */
    +
    + if (hh->uses_debug) {
    + set_debugreg(hh->debugreg0, 0);
    + set_debugreg(hh->debugreg1, 1);
    + /* ignore 4, 5 */
    + set_debugreg(hh->debugreg2, 2);
    + set_debugreg(hh->debugreg3, 3);
    + set_debugreg(hh->debugreg6, 6);
    + set_debugreg(hh->debugreg7, 7);
    + }
    +
    + return 0;
    +}
    +
    +static int cr_load_cpu_fpu(struct cr_hdr_cpu *hh, struct task_struct *t)
    +{
    + preempt_disable();
    +
    + __clear_fpu(t); /* in case we used FPU in user mode */
    +
    + if (!hh->used_math)
    + clear_used_math();
    +
    + preempt_enable();
    + return 0;
    +}
    +
    +static int cr_read_cpu_fpu(struct cr_ctx *ctx, struct task_struct *t)
    +{
    + void *xstate_buf = cr_hbuf_get(ctx, xstate_size);
    + int ret;
    +
    + ret = cr_kread(ctx, xstate_buf, xstate_size);
    + if (ret < 0)
    + goto out;
    +
    + /* i387 + MMU + SSE */
    + preempt_disable();
    +
    + /* init_fpu() also calls set_used_math() */
    + ret = init_fpu(current);
    + if (ret < 0)
    + return ret;
    +
    + memcpy(t->thread.xstate, xstate_buf, xstate_size);
    + preempt_enable();
    + out:
    + cr_hbuf_put(ctx, xstate_size);
    + return 0;
    +}
    +
    +#endif /* CONFIG_X86_64 */
    +
    +/* read the cpu state and registers for the current task */
    +int cr_read_cpu(struct cr_ctx *ctx)
    +{
    + struct cr_hdr_cpu *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + struct task_struct *t = current;
    + int parent, ret;
    +
    + parent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_CPU);
    + if (parent < 0) {
    + ret = parent;
    + goto out;
    + }
    +
    + ret = -EINVAL;
    +
    +#if 0 /* activate when containers are used */
    + if (parent != task_pid_vnr(t))
    + goto out;
    +#endif
    + /* FIX: sanity check for sensitive registers (eg. eflags) */
    +
    + cr_debug("math %d debug %d\n", hh->used_math, hh->uses_debug);
    +
    + ret = cr_load_cpu_regs(hh, t);
    + if (ret < 0)
    + goto out;
    + ret = cr_load_cpu_debug(hh, t);
    + if (ret < 0)
    + goto out;
    + ret = cr_load_cpu_fpu(hh, t);
    + if (ret < 0)
    + goto out;
    +
    + if (hh->used_math)
    + ret = cr_read_cpu_fpu(ctx, t);
    + out:
    + cr_hbuf_put(ctx, sizeof(*hh));
    + return ret;
    +}
    +
    +int cr_read_head_arch(struct cr_ctx *ctx)
    +{
    + struct cr_hdr_head_arch *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + int parent, ret = 0;
    +
    + parent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_HEAD_ARCH);
    + if (parent < 0) {
    + ret = parent;
    + goto out;
    + } else if (parent != 0)
    + goto out;
    +
    + /* FIX: verify compatibility of architecture features */
    +
    + /* verify FPU capabilities */
    + if (hh->has_fxsr != cpu_has_fxsr ||
    + hh->has_xsave != cpu_has_xsave ||
    + hh->xstate_size != xstate_size)
    + ret = -EINVAL;
    + out:
    + cr_hbuf_put(ctx, sizeof(*hh));
    +
    + return ret;
    +}
    diff --git a/checkpoint/checkpoint.c b/checkpoint/checkpoint.c
    index 71f761e..2948e2e 100644
    --- a/checkpoint/checkpoint.c
    +++ b/checkpoint/checkpoint.c
    @@ -20,6 +20,8 @@
    #include
    #include

    +#include "checkpoint_arch.h"
    +
    /* unique checkpoint identifier (FIXME: should be per-container ?) */
    static atomic_t cr_ctx_count = ATOMIC_INIT(0);

    @@ -88,7 +90,10 @@ static int cr_write_head(struct cr_ctx *ctx)

    ret = cr_write_obj(ctx, &h, hh);
    cr_hbuf_put(ctx, sizeof(*hh));
    - return ret;
    + if (ret < 0)
    + return ret;
    +
    + return cr_write_head_arch(ctx);
    }

    /* write the checkpoint trailer */
    @@ -143,8 +148,16 @@ static int cr_write_task(struct cr_ctx *ctx, struct task_struct *t)
    int ret;

    ret = cr_write_task_struct(ctx, t);
    - cr_debug("ret %d\n", ret);
    -
    + cr_debug("task_struct: ret %d\n", ret);
    + if (ret < 0)
    + goto out;
    + ret = cr_write_thread(ctx, t);
    + cr_debug("thread: ret %d\n", ret);
    + if (ret < 0)
    + goto out;
    + ret = cr_write_cpu(ctx, t);
    + cr_debug("cpu: ret %d\n", ret);
    + out:
    return ret;
    }

    diff --git a/checkpoint/checkpoint_arch.h b/checkpoint/checkpoint_arch.h
    new file mode 100644
    index 0000000..ada1369
    --- /dev/null
    +++ b/checkpoint/checkpoint_arch.h
    @@ -0,0 +1,9 @@
    +#include
    +
    +extern int cr_write_head_arch(struct cr_ctx *ctx);
    +extern int cr_write_thread(struct cr_ctx *ctx, struct task_struct *t);
    +extern int cr_write_cpu(struct cr_ctx *ctx, struct task_struct *t);
    +
    +extern int cr_read_head_arch(struct cr_ctx *ctx);
    +extern int cr_read_thread(struct cr_ctx *ctx);
    +extern int cr_read_cpu(struct cr_ctx *ctx);
    diff --git a/checkpoint/restart.c b/checkpoint/restart.c
    index fbfa52e..56bab40 100644
    --- a/checkpoint/restart.c
    +++ b/checkpoint/restart.c
    @@ -15,6 +15,8 @@
    #include
    #include

    +#include "checkpoint_arch.h"
    +
    /**
    * cr_read_obj - read a whole record (cr_hdr followed by payload)
    * @ctx: checkpoint context
    @@ -100,9 +102,9 @@ static int cr_read_head(struct cr_ctx *ctx)

    ctx->oflags = hh->flags;

    - /* FIX: verify compatibility of release, version and machine */
    + /* FIX: verify compatibility of release, version */

    - ret = 0;
    + ret = cr_read_head_arch(ctx);
    out:
    cr_hbuf_put(ctx, sizeof(*hh));
    return ret;
    @@ -172,8 +174,17 @@ static int cr_read_task(struct cr_ctx *ctx)
    int ret;

    ret = cr_read_task_struct(ctx);
    - cr_debug("ret %d\n", ret);
    + cr_debug("task_struct: ret %d\n", ret);
    + if (ret < 0)
    + goto out;
    + ret = cr_read_thread(ctx);
    + cr_debug("thread: ret %d\n", ret);
    + if (ret < 0)
    + goto out;
    + ret = cr_read_cpu(ctx);
    + cr_debug("cpu: ret %d\n", ret);

    + out:
    return ret;
    }

    diff --git a/include/linux/checkpoint_hdr.h b/include/linux/checkpoint_hdr.h
    index 79e4df2..a410416 100644
    --- a/include/linux/checkpoint_hdr.h
    +++ b/include/linux/checkpoint_hdr.h
    @@ -12,6 +12,7 @@

    #include
    #include
    +#include

    /*
    * To maintain compatibility between 32-bit and 64-bit architecture flavors,
    @@ -30,6 +31,7 @@ struct cr_hdr {
    /* header types */
    enum {
    CR_HDR_HEAD = 1,
    + CR_HDR_HEAD_ARCH,
    CR_HDR_STRING,

    CR_HDR_TASK = 101,
    --
    1.5.4.3

    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

  9. [RFC v9][PATCH 07/13] Infrastructure for shared objects

    Infrastructure to handle objects that may be shared and referenced by
    multiple tasks or other objects, e..g open files, memory address space
    etc.

    The state of shared objects is saved once. On the first encounter, the
    state is dumped and the object is assigned a unique identifier (objref)
    and also stored in a hash table (indexed by its physical kenrel address).
    From then on the object will be found in the hash and only its identifier
    is saved.

    On restart the identifier is looked up in the hash table; if not found
    then the state is read, the object is created, and added to the hash
    table (this time indexed by its identifier). Otherwise, the object in
    the hash table is used.

    Changelog[v4]:
    - Fix calculation of hash table size

    Changelog[v3]:
    - Use standard hlist_... for hash table

    Signed-off-by: Oren Laadan
    Acked-by: Serge Hallyn
    Signed-off-by: Dave Hansen
    ---
    checkpoint/Makefile | 2 +-
    checkpoint/objhash.c | 268 ++++++++++++++++++++++++++++++++++++++++++++
    checkpoint/sys.c | 4 +
    include/linux/checkpoint.h | 20 ++++
    4 files changed, 293 insertions(+), 1 deletions(-)
    create mode 100644 checkpoint/objhash.c

    diff --git a/checkpoint/Makefile b/checkpoint/Makefile
    index ac35033..9843fb9 100644
    --- a/checkpoint/Makefile
    +++ b/checkpoint/Makefile
    @@ -2,5 +2,5 @@
    # Makefile for linux checkpoint/restart.
    #

    -obj-$(CONFIG_CHECKPOINT_RESTART) += sys.o checkpoint.o restart.o \
    +obj-$(CONFIG_CHECKPOINT_RESTART) += sys.o checkpoint.o restart.o objhash.o \
    ckpt_mem.o rstr_mem.o
    diff --git a/checkpoint/objhash.c b/checkpoint/objhash.c
    new file mode 100644
    index 0000000..05b1a1b
    --- /dev/null
    +++ b/checkpoint/objhash.c
    @@ -0,0 +1,268 @@
    +/*
    + * Checkpoint-restart - object hash infrastructure to manage shared objects
    + *
    + * Copyright (C) 2008 Oren Laadan
    + *
    + * This file is subject to the terms and conditions of the GNU General Public
    + * License. See the file COPYING in the main directory of the Linux
    + * distribution for more details.
    + */
    +
    +#include
    +#include
    +#include
    +#include
    +
    +struct cr_objref {
    + int objref;
    + void *ptr;
    + unsigned short type;
    + unsigned short flags;
    + struct hlist_node hash;
    +};
    +
    +struct cr_objhash {
    + struct hlist_head *head;
    + int next_free_objref;
    +};
    +
    +#define CR_OBJHASH_NBITS 10
    +#define CR_OBJHASH_TOTAL (1UL << CR_OBJHASH_NBITS)
    +
    +static void cr_obj_ref_drop(struct cr_objref *obj)
    +{
    + switch (obj->type) {
    + case CR_OBJ_FILE:
    + fput((struct file *) obj->ptr);
    + break;
    + default:
    + BUG();
    + }
    +}
    +
    +static void cr_obj_ref_grab(struct cr_objref *obj)
    +{
    + switch (obj->type) {
    + case CR_OBJ_FILE:
    + get_file((struct file *) obj->ptr);
    + break;
    + default:
    + BUG();
    + }
    +}
    +
    +static void cr_objhash_clear(struct cr_objhash *objhash)
    +{
    + struct hlist_head *h = objhash->head;
    + struct hlist_node *n, *t;
    + struct cr_objref *obj;
    + int i;
    +
    + for (i = 0; i < CR_OBJHASH_TOTAL; i++) {
    + hlist_for_each_entry_safe(obj, n, t, &h[i], hash) {
    + cr_obj_ref_drop(obj);
    + kfree(obj);
    + }
    + }
    +}
    +
    +void cr_objhash_free(struct cr_ctx *ctx)
    +{
    + struct cr_objhash *objhash = ctx->objhash;
    +
    + if (objhash) {
    + cr_objhash_clear(objhash);
    + kfree(objhash->head);
    + kfree(ctx->objhash);
    + ctx->objhash = NULL;
    + }
    +}
    +
    +int cr_objhash_alloc(struct cr_ctx *ctx)
    +{
    + struct cr_objhash *objhash;
    + struct hlist_head *head;
    +
    + objhash = kzalloc(sizeof(*objhash), GFP_KERNEL);
    + if (!objhash)
    + return -ENOMEM;
    + head = kzalloc(CR_OBJHASH_TOTAL * sizeof(*head), GFP_KERNEL);
    + if (!head) {
    + kfree(objhash);
    + return -ENOMEM;
    + }
    +
    + objhash->head = head;
    + objhash->next_free_objref = 1;
    +
    + ctx->objhash = objhash;
    + return 0;
    +}
    +
    +static struct cr_objref *cr_obj_find_by_ptr(struct cr_ctx *ctx, void *ptr)
    +{
    + struct hlist_head *h;
    + struct hlist_node *n;
    + struct cr_objref *obj;
    +
    + h = &ctx->objhash->head[hash_ptr(ptr, CR_OBJHASH_NBITS)];
    + hlist_for_each_entry(obj, n, h, hash)
    + if (obj->ptr == ptr)
    + return obj;
    + return NULL;
    +}
    +
    +static struct cr_objref *cr_obj_find_by_objref(struct cr_ctx *ctx, int objref)
    +{
    + struct hlist_head *h;
    + struct hlist_node *n;
    + struct cr_objref *obj;
    +
    + h = &ctx->objhash->head[hash_ptr((void *) objref, CR_OBJHASH_NBITS)];
    + hlist_for_each_entry(obj, n, h, hash)
    + if (obj->objref == objref)
    + return obj;
    + return NULL;
    +}
    +
    +/**
    + * cr_obj_new - allocate an object and add to the hash table
    + * @ctx: checkpoint context
    + * @ptr: pointer to object
    + * @objref: unique object reference
    + * @type: object type
    + * @flags: object flags
    + *
    + * Allocate an object referring to @ptr and add to the hash table.
    + * If @objref is zero, assign a unique object reference and use @ptr
    + * as a hash key [checkpoint]. Else use @objref as a key [restart].
    + */
    +static struct cr_objref *cr_obj_new(struct cr_ctx *ctx, void *ptr, int objref,
    + unsigned short type, unsigned short flags)
    +{
    + struct cr_objref *obj;
    + int i;
    +
    + obj = kmalloc(sizeof(*obj), GFP_KERNEL);
    + if (!obj)
    + return NULL;
    +
    + obj->ptr = ptr;
    + obj->type = type;
    + obj->flags = flags;
    +
    + if (objref) {
    + /* use @objref to index (restart) */
    + obj->objref = objref;
    + i = hash_ptr((void *) objref, CR_OBJHASH_NBITS);
    + } else {
    + /* use @ptr to index, assign objref (checkpoint) */
    + obj->objref = ctx->objhash->next_free_objref++;;
    + i = hash_ptr(ptr, CR_OBJHASH_NBITS);
    + }
    +
    + hlist_add_head(&obj->hash, &ctx->objhash->head[i]);
    + cr_obj_ref_grab(obj);
    + return obj;
    +}
    +
    +/**
    + * cr_obj_add_ptr - add an object to the hash table if not already there
    + * @ctx: checkpoint context
    + * @ptr: pointer to object
    + * @objref: unique object reference [output]
    + * @type: object type
    + * @flags: object flags
    + *
    + * Look up the object pointed to by @ptr in the hash table. If it isn't
    + * already found there, then add the object to the table, and allocate a
    + * fresh unique object reference (objref). Fills the unique objref of
    + * the object into @objref.
    + * [This is used during checkpoint].
    + *
    + * Returns 0 if found, 1 if added, < 0 on error
    + */
    +int cr_obj_add_ptr(struct cr_ctx *ctx, void *ptr, int *objref,
    + unsigned short type, unsigned short flags)
    +{
    + struct cr_objref *obj;
    + int ret = 0;
    +
    + obj = cr_obj_find_by_ptr(ctx, ptr);
    + if (!obj) {
    + obj = cr_obj_new(ctx, ptr, 0, type, flags);
    + if (!obj)
    + return -ENOMEM;
    + else
    + ret = 1;
    + } else if (obj->type != type) /* sanity check */
    + return -EINVAL;
    + *objref = obj->objref;
    + return ret;
    +}
    +
    +/**
    + * cr_obj_add_ref - add an object with unique objref to the hash table
    + * @ctx: checkpoint context
    + * @ptr: pointer to object
    + * @objref: unique identifier - object reference
    + * @type: object type
    + * @flags: object flags
    + *
    + * Add the object pointer to by @ptr and identified by unique object
    + * reference given by @objref to the hash table (indexed by @objref).
    + * [This is used during restart].
    + */
    +int cr_obj_add_ref(struct cr_ctx *ctx, void *ptr, int objref,
    + unsigned short type, unsigned short flags)
    +{
    + struct cr_objref *obj;
    +
    + obj = cr_obj_new(ctx, ptr, objref, type, flags);
    + return obj ? 0 : -ENOMEM;
    +}
    +
    +/**
    + * cr_obj_get_by_ptr - find the unique object reference of an object
    + * @ctx: checkpoint context
    + * @ptr: pointer to object
    + * @type: object type
    + *
    + * Look up the unique object reference (objref) of the object pointed
    + * to by @ptr, and return that number, or 0 if not found.
    + * [This is used during checkpoint].
    + */
    +int cr_obj_get_by_ptr(struct cr_ctx *ctx, void *ptr, unsigned short type)
    +{
    + struct cr_objref *obj;
    +
    + obj = cr_obj_find_by_ptr(ctx, ptr);
    + if (!obj)
    + return -ESRCH;
    + if (obj->type != type)
    + return -EINVAL;
    + return obj->objref;
    +}
    +
    +/**
    + * cr_obj_get_by_ref - find an object given its unique object reference
    + * @ctx: checkpoint context
    + * @objref: unique identifier - object reference
    + * @type: object type
    + *
    + * Look up the object who is identified by unique object reference that
    + * is specified by @objref, and return a pointer to that matching object,
    + * or NULL if not found.
    + * [This is used during restart].
    + */
    +void *cr_obj_get_by_ref(struct cr_ctx *ctx, int objref, unsigned short type)
    +{
    + struct cr_objref *obj;
    +
    + obj = cr_obj_find_by_objref(ctx, objref);
    + if (!obj)
    + return NULL;
    + if (obj->type != type)
    + return ERR_PTR(-EINVAL);
    + return obj->ptr;
    +}
    diff --git a/checkpoint/sys.c b/checkpoint/sys.c
    index 455d124..b640bee 100644
    --- a/checkpoint/sys.c
    +++ b/checkpoint/sys.c
    @@ -140,6 +140,7 @@ static void cr_ctx_free(struct cr_ctx *ctx)
    path_put(ctx->vfsroot);

    cr_pgarr_free(ctx);
    + cr_objhash_free(ctx);

    kfree(ctx);
    }
    @@ -167,6 +168,9 @@ static struct cr_ctx *cr_ctx_alloc(int fd, unsigned long flags)
    if (!ctx->hbuf)
    goto err;

    + if (cr_objhash_alloc(ctx) < 0)
    + goto err;
    +
    return ctx;

    err:
    diff --git a/include/linux/checkpoint.h b/include/linux/checkpoint.h
    index 56f5fef..0e4ba74 100644
    --- a/include/linux/checkpoint.h
    +++ b/include/linux/checkpoint.h
    @@ -29,6 +29,8 @@ struct cr_ctx {
    void *hbuf; /* temporary buffer for headers */
    int hpos; /* position in headers buffer */

    + struct cr_objhash *objhash; /* hash for shared objects */
    +
    struct list_head pgarr_list; /* page array to dump VMA contents */

    struct path *vfsroot; /* container root (FIXME) */
    @@ -44,6 +46,24 @@ extern int cr_kread(struct cr_ctx *ctx, void *buf, int count);
    extern void *cr_hbuf_get(struct cr_ctx *ctx, int n);
    extern void cr_hbuf_put(struct cr_ctx *ctx, int n);

    +/* shared objects handling */
    +
    +enum {
    + CR_OBJ_FILE = 1,
    + CR_OBJ_MAX
    +};
    +
    +extern void cr_objhash_free(struct cr_ctx *ctx);
    +extern int cr_objhash_alloc(struct cr_ctx *ctx);
    +extern void *cr_obj_get_by_ref(struct cr_ctx *ctx,
    + int objref, unsigned short type);
    +extern int cr_obj_get_by_ptr(struct cr_ctx *ctx,
    + void *ptr, unsigned short type);
    +extern int cr_obj_add_ptr(struct cr_ctx *ctx, void *ptr, int *objref,
    + unsigned short type, unsigned short flags);
    +extern int cr_obj_add_ref(struct cr_ctx *ctx, void *ptr, int objref,
    + unsigned short type, unsigned short flags);
    +
    struct cr_hdr;

    extern int cr_write_obj(struct cr_ctx *ctx, struct cr_hdr *h, void *buf);
    --
    1.5.4.3

    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

  10. [RFC v9][PATCH 05/13] Dump memory address space

    For each VMA, there is a 'struct cr_vma'; if the VMA is file-mapped,
    it will be followed by the file name. Then comes the actual contents,
    in one or more chunk: each chunk begins with a header that specifies
    how many pages it holds, then the virtual addresses of all the dumped
    pages in that chunk, followed by the actual contents of all dumped
    pages. A header with zero number of pages marks the end of the contents.
    Then comes the next VMA and so on.

    Changelog[v9]:
    - Introduce cr_ctx_checkpoint() for checkpoint-specific ctx setup
    - Test if __d_path() changes mnt/dentry (when crossing filesystem
    namespace boundary). for now cr_fill_fname() fails the checkpoint.

    Changelog[v7]:
    - Fix argument given to kunmap_atomic() in memory dump/restore

    Changelog[v6]:
    - Balance all calls to cr_hbuf_get() with matching cr_hbuf_put()
    (even though it's not really needed)

    Changelog[v5]:
    - Improve memory dump code (following Dave Hansen's comments)
    - Change dump format (and code) to allow chunks of
    instead of one long list of each
    - Fix use of follow_page() to avoid faulting in non-present pages

    Changelog[v4]:
    - Use standard list_... for cr_pgarr

    Signed-off-by: Oren Laadan
    Acked-by: Serge Hallyn
    Signed-off-by: Dave Hansen
    ---
    arch/x86/include/asm/checkpoint_hdr.h | 5 +
    arch/x86/mm/checkpoint.c | 31 ++
    checkpoint/Makefile | 3 +-
    checkpoint/checkpoint.c | 79 ++++++
    checkpoint/checkpoint_arch.h | 2 +
    checkpoint/checkpoint_mem.h | 41 +++
    checkpoint/ckpt_mem.c | 500 +++++++++++++++++++++++++++++++++
    checkpoint/sys.c | 11 +
    include/linux/checkpoint.h | 12 +
    include/linux/checkpoint_hdr.h | 32 ++
    10 files changed, 715 insertions(+), 1 deletions(-)
    create mode 100644 checkpoint/checkpoint_mem.h
    create mode 100644 checkpoint/ckpt_mem.c

    diff --git a/arch/x86/include/asm/checkpoint_hdr.h b/arch/x86/include/asm/checkpoint_hdr.h
    index 6325062..33f4c70 100644
    --- a/arch/x86/include/asm/checkpoint_hdr.h
    +++ b/arch/x86/include/asm/checkpoint_hdr.h
    @@ -82,4 +82,9 @@ struct cr_hdr_cpu {
    /* thread_xstate contents follow (if used_math) */
    } __attribute__((aligned(8)));

    +struct cr_hdr_mm_context {
    + __s16 ldt_entry_size;
    + __s16 nldt;
    +} __attribute__((aligned(8)));
    +
    #endif /* __ASM_X86_CKPT_HDR__H */
    diff --git a/arch/x86/mm/checkpoint.c b/arch/x86/mm/checkpoint.c
    index 8dd6d2d..757936e 100644
    --- a/arch/x86/mm/checkpoint.c
    +++ b/arch/x86/mm/checkpoint.c
    @@ -221,3 +221,34 @@ int cr_write_head_arch(struct cr_ctx *ctx)

    return ret;
    }
    +
    +/* dump the mm->context state */
    +int cr_write_mm_context(struct cr_ctx *ctx, struct mm_struct *mm, int parent)
    +{
    + struct cr_hdr h;
    + struct cr_hdr_mm_context *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + int ret;
    +
    + h.type = CR_HDR_MM_CONTEXT;
    + h.len = sizeof(*hh);
    + h.parent = parent;
    +
    + mutex_lock(&mm->context.lock);
    +
    + hh->ldt_entry_size = LDT_ENTRY_SIZE;
    + hh->nldt = mm->context.size;
    +
    + cr_debug("nldt %d\n", hh->nldt);
    +
    + ret = cr_write_obj(ctx, &h, hh);
    + cr_hbuf_put(ctx, sizeof(*hh));
    + if (ret < 0)
    + goto out;
    +
    + ret = cr_kwrite(ctx, mm->context.ldt,
    + mm->context.size * LDT_ENTRY_SIZE);
    +
    + out:
    + mutex_unlock(&mm->context.lock);
    + return ret;
    +}
    diff --git a/checkpoint/Makefile b/checkpoint/Makefile
    index d2df68c..3a0df6d 100644
    --- a/checkpoint/Makefile
    +++ b/checkpoint/Makefile
    @@ -2,4 +2,5 @@
    # Makefile for linux checkpoint/restart.
    #

    -obj-$(CONFIG_CHECKPOINT_RESTART) += sys.o checkpoint.o restart.o
    +obj-$(CONFIG_CHECKPOINT_RESTART) += sys.o checkpoint.o restart.o \
    + ckpt_mem.o
    diff --git a/checkpoint/checkpoint.c b/checkpoint/checkpoint.c
    index 2948e2e..e162753 100644
    --- a/checkpoint/checkpoint.c
    +++ b/checkpoint/checkpoint.c
    @@ -58,6 +58,64 @@ int cr_write_string(struct cr_ctx *ctx, char *str, int len)
    return cr_write_obj(ctx, &h, str);
    }

    +/**
    + * cr_fill_fname - return pathname of a given file
    + * @path: path name
    + * @root: relative root
    + * @buf: buffer for pathname
    + * @n: buffer length (in) and pathname length (out)
    + */
    +static char *
    +cr_fill_fname(struct path *path, struct path *root, char *buf, int *n)
    +{
    + struct path tmp = *root;
    + char *fname;
    +
    + BUG_ON(!buf);
    + fname = __d_path(path, &tmp, buf, *n);
    + if (!IS_ERR(fname))
    + *n = (buf + (*n) - fname);
    + /*
    + * FIXME: if __d_path() changed these, it must have stepped out of
    + * init's namespace. Since currently we require a unified namespace
    + * within the container: simply fail.
    + */
    + if (tmp.mnt != root->mnt || tmp.dentry != root->dentry)
    + fname = ERR_PTR(-EBADF);
    +
    + return fname;
    +}
    +
    +/**
    + * cr_write_fname - write a file name
    + * @ctx: checkpoint context
    + * @path: path name
    + * @root: relative root
    + */
    +int cr_write_fname(struct cr_ctx *ctx, struct path *path, struct path *root)
    +{
    + struct cr_hdr h;
    + char *buf, *fname;
    + int ret, flen;
    +
    + flen = PATH_MAX;
    + buf = kmalloc(flen, GFP_KERNEL);
    + if (!buf)
    + return -ENOMEM;
    +
    + fname = cr_fill_fname(path, root, buf, &flen);
    + if (!IS_ERR(fname)) {
    + h.type = CR_HDR_FNAME;
    + h.len = flen;
    + h.parent = 0;
    + ret = cr_write_obj(ctx, &h, fname);
    + } else
    + ret = PTR_ERR(fname);
    +
    + kfree(buf);
    + return ret;
    +}
    +
    /* write the checkpoint header */
    static int cr_write_head(struct cr_ctx *ctx)
    {
    @@ -151,6 +209,10 @@ static int cr_write_task(struct cr_ctx *ctx, struct task_struct *t)
    cr_debug("task_struct: ret %d\n", ret);
    if (ret < 0)
    goto out;
    + ret = cr_write_mm(ctx, t);
    + cr_debug("memory: ret %d\n", ret);
    + if (ret < 0)
    + goto out;
    ret = cr_write_thread(ctx, t);
    cr_debug("thread: ret %d\n", ret);
    if (ret < 0)
    @@ -161,10 +223,27 @@ static int cr_write_task(struct cr_ctx *ctx, struct task_struct *t)
    return ret;
    }

    +static int cr_ctx_checkpoint(struct cr_ctx *ctx, pid_t pid)
    +{
    + ctx->root_pid = pid;
    +
    + /*
    + * assume checkpointer is in container's root vfs
    + * FIXME: this works for now, but will change with real containers
    + */
    + ctx->vfsroot = &current->fs->root;
    + path_get(ctx->vfsroot);
    +
    + return 0;
    +}
    +
    int do_checkpoint(struct cr_ctx *ctx, pid_t pid)
    {
    int ret;

    + ret = cr_ctx_checkpoint(ctx);
    + if (ret < 0)
    + goto out;
    ret = cr_write_head(ctx);
    if (ret < 0)
    goto out;
    diff --git a/checkpoint/checkpoint_arch.h b/checkpoint/checkpoint_arch.h
    index ada1369..f06c7eb 100644
    --- a/checkpoint/checkpoint_arch.h
    +++ b/checkpoint/checkpoint_arch.h
    @@ -3,6 +3,8 @@
    extern int cr_write_head_arch(struct cr_ctx *ctx);
    extern int cr_write_thread(struct cr_ctx *ctx, struct task_struct *t);
    extern int cr_write_cpu(struct cr_ctx *ctx, struct task_struct *t);
    +extern int cr_write_mm_context(struct cr_ctx *ctx,
    + struct mm_struct *mm, int parent);

    extern int cr_read_head_arch(struct cr_ctx *ctx);
    extern int cr_read_thread(struct cr_ctx *ctx);
    diff --git a/checkpoint/checkpoint_mem.h b/checkpoint/checkpoint_mem.h
    new file mode 100644
    index 0000000..85546f4
    --- /dev/null
    +++ b/checkpoint/checkpoint_mem.h
    @@ -0,0 +1,41 @@
    +#ifndef _CHECKPOINT_CKPT_MEM_H_
    +#define _CHECKPOINT_CKPT_MEM_H_
    +/*
    + * Generic container checkpoint-restart
    + *
    + * Copyright (C) 2008 Oren Laadan
    + *
    + * This file is subject to the terms and conditions of the GNU General Public
    + * License. See the file COPYING in the main directory of the Linux
    + * distribution for more details.
    + */
    +
    +#include
    +
    +/*
    + * page-array chains: each cr_pgarr describes a set of
    + * tuples (where vaddr is the virtual address of a page in a particular mm).
    + * Specifically, we use separate arrays so that all vaddrs can be written
    + * and read at once.
    + */
    +
    +struct cr_pgarr {
    + unsigned long *vaddrs;
    + struct page **pages;
    + unsigned int nr_used;
    + struct list_head list;
    +};
    +
    +#define CR_PGARR_TOTAL (PAGE_SIZE / sizeof(void *))
    +#define CR_PGARR_CHUNK (4 * CR_PGARR_TOTAL)
    +
    +extern void cr_pgarr_free(struct cr_ctx *ctx);
    +extern struct cr_pgarr *cr_pgarr_current(struct cr_ctx *ctx);
    +extern void cr_pgarr_reset_all(struct cr_ctx *ctx);
    +
    +static inline int cr_pgarr_is_full(struct cr_pgarr *pgarr)
    +{
    + return (pgarr->nr_used == CR_PGARR_TOTAL);
    +}
    +
    +#endif /* _CHECKPOINT_CKPT_MEM_H_ */
    diff --git a/checkpoint/ckpt_mem.c b/checkpoint/ckpt_mem.c
    new file mode 100644
    index 0000000..66a2c39
    --- /dev/null
    +++ b/checkpoint/ckpt_mem.c
    @@ -0,0 +1,500 @@
    +/*
    + * Checkpoint memory contents
    + *
    + * Copyright (C) 2008 Oren Laadan
    + *
    + * This file is subject to the terms and conditions of the GNU General Public
    + * License. See the file COPYING in the main directory of the Linux
    + * distribution for more details.
    + */
    +
    +#include
    +#include
    +#include
    +#include
    +#include
    +#include
    +#include
    +#include
    +
    +#include "checkpoint_arch.h"
    +#include "checkpoint_mem.h"
    +
    +/*
    + * utilities to alloc, free, and handle 'struct cr_pgarr' (page-arrays)
    + * (common to ckpt_mem.c and rstr_mem.c).
    + *
    + * The checkpoint context structure has two members for page-arrays:
    + * ctx->pgarr_list: list head of the page-array chain
    + *
    + * During checkpoint (and restart) the chain tracks the dirty pages (page
    + * pointer and virtual address) of each MM. For a particular MM, these are
    + * always added to the head of the page-array chain (ctx->pgarr_list).
    + * This "current" page-array advances as necessary, and new page-array
    + * descriptors are allocated on-demand. Before the next chunk of pages,
    + * the chain is reset but not freed (that is, dereference page pointers).
    + */
    +
    +/* return first page-array in the chain */
    +static inline struct cr_pgarr *cr_pgarr_first(struct cr_ctx *ctx)
    +{
    + if (list_empty(&ctx->pgarr_list))
    + return NULL;
    + return list_first_entry(&ctx->pgarr_list, struct cr_pgarr, list);
    +}
    +
    +/* release pages referenced by a page-array */
    +static void cr_pgarr_release_pages(struct cr_pgarr *pgarr)
    +{
    + int i;
    +
    + cr_debug("nr_used %d\n", pgarr->nr_used);
    + /*
    + * although both checkpoint and restart use 'nr_used', we only
    + * collect pages during checkpoint; in restart we simply return
    + */
    + if (!pgarr->pages)
    + return;
    + for (i = pgarr->nr_used; i--; /**/)
    + page_cache_release(pgarr->pages[i]);
    +}
    +
    +/* free a single page-array object */
    +static void cr_pgarr_free_one(struct cr_pgarr *pgarr)
    +{
    + cr_pgarr_release_pages(pgarr);
    + kfree(pgarr->pages);
    + kfree(pgarr->vaddrs);
    + kfree(pgarr);
    +}
    +
    +/* free a chain of page-arrays */
    +void cr_pgarr_free(struct cr_ctx *ctx)
    +{
    + struct cr_pgarr *pgarr, *tmp;
    +
    + list_for_each_entry_safe(pgarr, tmp, &ctx->pgarr_list, list) {
    + list_del(&pgarr->list);
    + cr_pgarr_free_one(pgarr);
    + }
    +}
    +
    +/* allocate a single page-array object */
    +static struct cr_pgarr *cr_pgarr_alloc_one(unsigned long flags)
    +{
    + struct cr_pgarr *pgarr;
    +
    + pgarr = kzalloc(sizeof(*pgarr), GFP_KERNEL);
    + if (!pgarr)
    + return NULL;
    +
    + pgarr->vaddrs = kmalloc(CR_PGARR_TOTAL * sizeof(unsigned long),
    + GFP_KERNEL);
    + if (!pgarr->vaddrs)
    + goto nomem;
    +
    + /* pgarr->pages is needed only for checkpoint */
    + if (flags & CR_CTX_CKPT) {
    + pgarr->pages = kmalloc(CR_PGARR_TOTAL * sizeof(struct page *),
    + GFP_KERNEL);
    + if (!pgarr->pages)
    + goto nomem;
    + }
    +
    + return pgarr;
    +
    + nomem:
    + cr_pgarr_free_one(pgarr);
    + return NULL;
    +}
    +
    +/* cr_pgarr_current - return the next available page-array in the chain
    + * @ctx: checkpoint context
    + *
    + * Returns the first page-array in the list that has space. Extends the
    + * list if none has space.
    + */
    +struct cr_pgarr *cr_pgarr_current(struct cr_ctx *ctx)
    +{
    + struct cr_pgarr *pgarr;
    +
    + pgarr = cr_pgarr_first(ctx);
    + if (pgarr && !cr_pgarr_is_full(pgarr))
    + goto out;
    + pgarr = cr_pgarr_alloc_one(ctx->flags);
    + if (!pgarr)
    + goto out;
    + list_add(&pgarr->list, &ctx->pgarr_list);
    + out:
    + return pgarr;
    +}
    +
    +/* reset the page-array chain (dropping page references if necessary) */
    +void cr_pgarr_reset_all(struct cr_ctx *ctx)
    +{
    + struct cr_pgarr *pgarr;
    +
    + list_for_each_entry(pgarr, &ctx->pgarr_list, list) {
    + cr_pgarr_release_pages(pgarr);
    + pgarr->nr_used = 0;
    + }
    +}
    +
    +/*
    + * Checkpoint is outside the context of the checkpointee, so one cannot
    + * simply read pages from user-space. Instead, we scan the address space
    + * of the target to cherry-pick pages of interest. Selected pages are
    + * enlisted in a page-array chain (attached to the checkpoint context).
    + * To save their contents, each page is mapped to kernel memory and then
    + * dumped to the file descriptor.
    + */
    +
    +
    +/**
    + * cr_private_follow_page - return page pointer for dirty pages
    + * @vma - target vma
    + * @addr - page address
    + *
    + * Looks up the page that correspond to the address in the vma, and
    + * returns the page if it was modified (and grabs a reference to it),
    + * or otherwise returns NULL (or error).
    + *
    + * This function should _only_ called for private vma's.
    + */
    +static struct page *
    +cr_private_follow_page(struct vm_area_struct *vma, unsigned long addr)
    +{
    + struct page *page;
    +
    + BUG_ON(vma->vm_flags & (VM_SHARED | VM_MAYSHARE));
    +
    + /*
    + * simplified version of get_user_pages(): already have vma,
    + * only need FOLL_ANON, and (for now) ignore fault stats.
    + *
    + * follow_page() will return NULL if the page is not present
    + * (swapped), ZERO_PAGE(0) if the pte wasn't allocated, and
    + * the actual page pointer otherwise.
    + *
    + * FIXME: consolidate with get_user_pages()
    + */
    +
    + cond_resched();
    + while (!(page = follow_page(vma, addr, FOLL_ANON | FOLL_GET))) {
    + int ret;
    +
    + /* the page is swapped out - bring it in (optimize ?) */
    + ret = handle_mm_fault(vma->vm_mm, vma, addr, 0);
    + if (ret & VM_FAULT_ERROR) {
    + if (ret & VM_FAULT_OOM)
    + return ERR_PTR(-ENOMEM);
    + else if (ret & VM_FAULT_SIGBUS)
    + return ERR_PTR(-EFAULT);
    + else
    + BUG();
    + break;
    + }
    + cond_resched();
    + }
    +
    + if (IS_ERR(page))
    + return page;
    +
    + /*
    + * We only care about dirty pages: either non-zero page, or
    + * file-backed (copy-on-write) that were touched. For the latter,
    + * the page_mapping() will be unset because it will no longer be
    + * mapped to the original file after having been modified.
    + */
    + if (page == ZERO_PAGE(0)) {
    + /* this is the zero page: ignore */
    + page_cache_release(page);
    + page = NULL;
    + } else if (vma->vm_file && (page_mapping(page) != NULL)) {
    + /* file backed clean cow: ignore */
    + page_cache_release(page);
    + page = NULL;
    + }
    +
    + return page;
    +}
    +
    +/**
    + * cr_private_vma_fill_pgarr - fill a page-array with addr/page tuples
    + * @ctx - checkpoint context
    + * @pgarr - page-array to fill
    + * @vma - vma to scan
    + * @start - start address (updated)
    + *
    + * Returns the number of pages collected
    + */
    +static int
    +cr_private_vma_fill_pgarr(struct cr_ctx *ctx, struct cr_pgarr *pgarr,
    + struct vm_area_struct *vma, unsigned long *start)
    +{
    + unsigned long end = vma->vm_end;
    + unsigned long addr = *start;
    + int orig_used = pgarr->nr_used;
    +
    + /* this function is only for private memory (anon or file-mapped) */
    + BUG_ON(vma->vm_flags & (VM_SHARED | VM_MAYSHARE));
    +
    + while (addr < end) {
    + struct page *page;
    +
    + page = cr_private_follow_page(vma, addr);
    + if (IS_ERR(page))
    + return PTR_ERR(page);
    +
    + if (page) {
    + pgarr->pages[pgarr->nr_used] = page;
    + pgarr->vaddrs[pgarr->nr_used] = addr;
    + pgarr->nr_used++;
    + }
    +
    + addr += PAGE_SIZE;
    +
    + if (cr_pgarr_is_full(pgarr))
    + break;
    + }
    +
    + *start = addr;
    + return pgarr->nr_used - orig_used;
    +}
    +
    +/* dump contents of a pages: use kmap_atomic() to avoid TLB flush */
    +static int cr_page_write(struct cr_ctx *ctx, struct page *page, char *buf)
    +{
    + void *ptr;
    +
    + ptr = kmap_atomic(page, KM_USER1);
    + memcpy(buf, ptr, PAGE_SIZE);
    + kunmap_atomic(ptr, KM_USER1);
    +
    + return cr_kwrite(ctx, buf, PAGE_SIZE);
    +}
    +
    +/**
    + * cr_vma_dump_pages - dump pages listed in the ctx page-array chain
    + * @ctx - checkpoint context
    + * @total - total number of pages
    + *
    + * First dump all virtual addresses, followed by the contents of all pages
    + */
    +static int cr_vma_dump_pages(struct cr_ctx *ctx, int total)
    +{
    + struct cr_pgarr *pgarr;
    + char *buf;
    + int i, ret = 0;
    +
    + if (!total)
    + return 0;
    +
    + list_for_each_entry_reverse(pgarr, &ctx->pgarr_list, list) {
    + ret = cr_kwrite(ctx, pgarr->vaddrs,
    + pgarr->nr_used * sizeof(*pgarr->vaddrs));
    + if (ret < 0)
    + return ret;
    + }
    +
    + buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
    + if (!buf)
    + return -ENOMEM;
    +
    + list_for_each_entry_reverse(pgarr, &ctx->pgarr_list, list) {
    + for (i = 0; i < pgarr->nr_used; i++) {
    + ret = cr_page_write(ctx, pgarr->pages[i], buf);
    + if (ret < 0)
    + goto out;
    + }
    + }
    +
    + out:
    + kfree(buf);
    + return ret;
    +}
    +
    +/**
    + * cr_write_private_vma_contents - dump contents of a VMA with private memory
    + * @ctx - checkpoint context
    + * @vma - vma to scan
    + *
    + * Collect lists of pages that needs to be dumped, and corresponding
    + * virtual addresses into ctx->pgarr_list page-array chain. Then dump
    + * the addresses, followed by the page contents.
    + */
    +static int
    +cr_write_private_vma_contents(struct cr_ctx *ctx, struct vm_area_struct *vma)
    +{
    + struct cr_hdr h;
    + struct cr_hdr_pgarr *hh;
    + unsigned long addr = vma->vm_start;
    + struct cr_pgarr *pgarr;
    + unsigned long cnt = 0;
    + int ret;
    +
    + /*
    + * Work iteratively, collecting and dumping at most CR_PGARR_CHUNK
    + * in each round. Each iterations is divided into two steps:
    + *
    + * (1) scan: scan through the PTEs of the vma to collect the pages
    + * to dump (later we'll also make them COW), while keeping a list
    + * of pages and their corresponding addresses on ctx->pgarr_list.
    + *
    + * (2) dump: write out a header specifying how many pages, followed
    + * by the addresses of all pages in ctx->pgarr_list, followed by
    + * the actual contents of all pages. (Then, release the references
    + * to the pages and reset the page-array chain).
    + *
    + * (This split makes the logic simpler by first counting the pages
    + * that need saving. More importantly, it allows for a future
    + * optimization that will reduce application downtime by deferring
    + * the actual write-out of the data to after the application is
    + * allowed to resume execution).
    + *
    + * After dumpting the entire contents, conclude with a header that
    + * specifies 0 pages to mark the end of the contents.
    + */
    +
    + h.type = CR_HDR_PGARR;
    + h.len = sizeof(*hh);
    + h.parent = 0;
    +
    + while (addr < vma->vm_end) {
    + pgarr = cr_pgarr_current(ctx);
    + if (!pgarr)
    + return -ENOMEM;
    + ret = cr_private_vma_fill_pgarr(ctx, pgarr, vma, &addr);
    + if (ret < 0)
    + return ret;
    + cnt += ret;
    +
    + /* did we complete a chunk, or is this the last chunk ? */
    + if (cnt >= CR_PGARR_CHUNK || (cnt && addr == vma->vm_end)) {
    + hh = cr_hbuf_get(ctx, sizeof(*hh));
    + hh->nr_pages = cnt;
    + ret = cr_write_obj(ctx, &h, hh);
    + cr_hbuf_put(ctx, sizeof(*hh));
    + if (ret < 0)
    + return ret;
    +
    + ret = cr_vma_dump_pages(ctx, cnt);
    + if (ret < 0)
    + return ret;
    +
    + cr_pgarr_reset_all(ctx);
    + }
    + }
    +
    + /* mark end of contents with header saying "0" pages */
    + hh = cr_hbuf_get(ctx, sizeof(*hh));
    + hh->nr_pages = 0;
    + ret = cr_write_obj(ctx, &h, hh);
    + cr_hbuf_put(ctx, sizeof(*hh));
    +
    + return ret;
    +}
    +
    +static int cr_write_vma(struct cr_ctx *ctx, struct vm_area_struct *vma)
    +{
    + struct cr_hdr h;
    + struct cr_hdr_vma *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + int vma_type, ret;
    +
    + h.type = CR_HDR_VMA;
    + h.len = sizeof(*hh);
    + h.parent = 0;
    +
    + hh->vm_start = vma->vm_start;
    + hh->vm_end = vma->vm_end;
    + hh->vm_page_prot = vma->vm_page_prot.pgprot;
    + hh->vm_flags = vma->vm_flags;
    + hh->vm_pgoff = vma->vm_pgoff;
    +
    + if (vma->vm_flags & (VM_SHARED | VM_IO | VM_HUGETLB | VM_NONLINEAR)) {
    + pr_warning("c/r: unsupported VMA %#lx\n", vma->vm_flags);
    + cr_hbuf_put(ctx, sizeof(*hh));
    + return -ENOSYS;
    + }
    +
    + /* by default assume anon memory */
    + vma_type = CR_VMA_ANON;
    +
    + /*
    + * if there is a backing file, assume private-mapped
    + * (FIXME: check if the file is unlinked)
    + */
    + if (vma->vm_file)
    + vma_type = CR_VMA_FILE;
    +
    + hh->vma_type = vma_type;
    +
    + ret = cr_write_obj(ctx, &h, hh);
    + cr_hbuf_put(ctx, sizeof(*hh));
    + if (ret < 0)
    + return ret;
    +
    + /* save the file name, if relevant */
    + if (vma->vm_file) {
    + ret = cr_write_fname(ctx, &vma->vm_file->f_path, ctx->vfsroot);
    + if (ret < 0)
    + return ret;
    + }
    +
    + return cr_write_private_vma_contents(ctx, vma);
    +}
    +
    +int cr_write_mm(struct cr_ctx *ctx, struct task_struct *t)
    +{
    + struct cr_hdr h;
    + struct cr_hdr_mm *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + struct mm_struct *mm;
    + struct vm_area_struct *vma;
    + int objref, ret;
    +
    + h.type = CR_HDR_MM;
    + h.len = sizeof(*hh);
    + h.parent = task_pid_vnr(t);
    +
    + mm = get_task_mm(t);
    +
    + objref = 0; /* will be meaningful with multiple processes */
    + hh->objref = objref;
    +
    + down_read(&mm->mmap_sem);
    +
    + hh->start_code = mm->start_code;
    + hh->end_code = mm->end_code;
    + hh->start_data = mm->start_data;
    + hh->end_data = mm->end_data;
    + hh->start_brk = mm->start_brk;
    + hh->brk = mm->brk;
    + hh->start_stack = mm->start_stack;
    + hh->arg_start = mm->arg_start;
    + hh->arg_end = mm->arg_end;
    + hh->env_start = mm->env_start;
    + hh->env_end = mm->env_end;
    +
    + hh->map_count = mm->map_count;
    +
    + /* FIX: need also mm->flags */
    +
    + ret = cr_write_obj(ctx, &h, hh);
    + cr_hbuf_put(ctx, sizeof(*hh));
    + if (ret < 0)
    + goto out;
    +
    + /* write the vma's */
    + for (vma = mm->mmap; vma; vma = vma->vm_next) {
    + ret = cr_write_vma(ctx, vma);
    + if (ret < 0)
    + goto out;
    + }
    +
    + ret = cr_write_mm_context(ctx, mm, objref);
    +
    + out:
    + up_read(&mm->mmap_sem);
    + mmput(mm);
    + return ret;
    +}
    diff --git a/checkpoint/sys.c b/checkpoint/sys.c
    index bd14ef9..455d124 100644
    --- a/checkpoint/sys.c
    +++ b/checkpoint/sys.c
    @@ -16,6 +16,8 @@
    #include
    #include

    +#include "checkpoint_mem.h"
    +
    /*
    * Helpers to write(read) from(to) kernel space to(from) the checkpoint
    * image file descriptor (similar to how a core-dump is performed).
    @@ -131,7 +133,14 @@ static void cr_ctx_free(struct cr_ctx *ctx)
    {
    if (ctx->file)
    fput(ctx->file);
    +
    kfree(ctx->hbuf);
    +
    + if (ctx->vfsroot)
    + path_put(ctx->vfsroot);
    +
    + cr_pgarr_free(ctx);
    +
    kfree(ctx);
    }

    @@ -146,6 +155,8 @@ static struct cr_ctx *cr_ctx_alloc(int fd, unsigned long flags)

    ctx->flags = flags;

    + INIT_LIST_HEAD(&ctx->pgarr_list);
    +
    err = -EBADF;
    ctx->file = fget(fd);
    if (!ctx->file)
    diff --git a/include/linux/checkpoint.h b/include/linux/checkpoint.h
    index 9c119ba..7786e9b 100644
    --- a/include/linux/checkpoint.h
    +++ b/include/linux/checkpoint.h
    @@ -10,6 +10,9 @@
    * distribution for more details.
    */

    +#include
    +#include
    +
    #define CR_VERSION 1

    struct cr_ctx {
    @@ -25,6 +28,10 @@ struct cr_ctx {

    void *hbuf; /* temporary buffer for headers */
    int hpos; /* position in headers buffer */
    +
    + struct list_head pgarr_list; /* page array to dump VMA contents */
    +
    + struct path *vfsroot; /* container root (FIXME) */
    };

    /* cr_ctx: flags */
    @@ -41,13 +48,18 @@ struct cr_hdr;

    extern int cr_write_obj(struct cr_ctx *ctx, struct cr_hdr *h, void *buf);
    extern int cr_write_string(struct cr_ctx *ctx, char *str, int len);
    +extern int cr_write_fname(struct cr_ctx *ctx,
    + struct path *path, struct path *root);

    extern int cr_read_obj(struct cr_ctx *ctx, struct cr_hdr *h, void *buf, int n);
    extern int cr_read_obj_type(struct cr_ctx *ctx, void *buf, int n, int type);
    extern int cr_read_string(struct cr_ctx *ctx, void *str, int len);

    extern int do_checkpoint(struct cr_ctx *ctx, pid_t pid);
    +extern int cr_write_mm(struct cr_ctx *ctx, struct task_struct *t);
    +
    extern int do_restart(struct cr_ctx *ctx, pid_t pid);
    +extern int cr_read_mm(struct cr_ctx *ctx);

    #define cr_debug(fmt, args...) \
    pr_debug("[%d:c/r:%s] " fmt, task_pid_vnr(current), __func__, ## args)
    diff --git a/include/linux/checkpoint_hdr.h b/include/linux/checkpoint_hdr.h
    index a410416..c2e1022 100644
    --- a/include/linux/checkpoint_hdr.h
    +++ b/include/linux/checkpoint_hdr.h
    @@ -33,6 +33,7 @@ enum {
    CR_HDR_HEAD = 1,
    CR_HDR_HEAD_ARCH,
    CR_HDR_STRING,
    + CR_HDR_FNAME,

    CR_HDR_TASK = 101,
    CR_HDR_THREAD,
    @@ -40,6 +41,7 @@ enum {

    CR_HDR_MM = 201,
    CR_HDR_VMA,
    + CR_HDR_PGARR,
    CR_HDR_MM_CONTEXT,

    CR_HDR_TAIL = 5001
    @@ -74,4 +76,34 @@ struct cr_hdr_task {
    __s32 task_comm_len;
    } __attribute__((aligned(8)));

    +struct cr_hdr_mm {
    + __u32 objref; /* identifier for shared objects */
    + __u32 map_count;
    +
    + __u64 start_code, end_code, start_data, end_data;
    + __u64 start_brk, brk, start_stack;
    + __u64 arg_start, arg_end, env_start, env_end;
    +} __attribute__((aligned(8)));
    +
    +/* vma subtypes */
    +enum vm_type {
    + CR_VMA_ANON = 1,
    + CR_VMA_FILE
    +};
    +
    +struct cr_hdr_vma {
    + __u32 vma_type;
    + __u32 _padding;
    +
    + __u64 vm_start;
    + __u64 vm_end;
    + __u64 vm_page_prot;
    + __u64 vm_flags;
    + __u64 vm_pgoff;
    +} __attribute__((aligned(8)));
    +
    +struct cr_hdr_pgarr {
    + __u64 nr_pages; /* number of pages to saved */
    +} __attribute__((aligned(8)));
    +
    #endif /* _CHECKPOINT_CKPT_HDR_H_ */
    --
    1.5.4.3

    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

  11. [RFC v9][PATCH 03/13] General infrastructure for checkpoint restart

    Add those interfaces, as well as helpers needed to easily manage the
    file format. The code is roughly broken out as follows:

    checkpoint/sys.c - user/kernel data transfer, as well as setup of the
    CR context (a per-checkpoint data structure for housekeeping)
    checkpoint/checkpoint.c - output wrappers and basic checkpoint handling
    checkpoint/restart.c - input wrappers and basic restart handling

    For now, we can only checkpoint the 'current' task ("self" checkpoint),
    and the 'pid' argument to to the syscall is ignored.

    Patches to add the per-architecture support as well as the actual
    work to do the memory checkpoint follow in subsequent patches.

    Changelog[v9]:
    - cr_kwrite/cr_kread() use file->f_op->write() directly
    - Drop cr_uwrite/cr_uread() since they aren't used anywhere

    Changelog[v6]:
    - Balance all calls to cr_hbuf_get() with matching cr_hbuf_put()
    (although it's not really needed)

    Changelog[v5]:
    - Rename headers files s/ckpt/checkpoint/

    Changelog[v2]:
    - Added utsname->{release,version,machine} to checkpoint header
    - Pad header structures to 64 bits to ensure compatibility

    Signed-off-by: Oren Laadan
    Acked-by: Serge Hallyn
    Signed-off-by: Dave Hansen
    ---
    Makefile | 2 +-
    checkpoint/Makefile | 2 +-
    checkpoint/checkpoint.c | 171 ++++++++++++++++++++++++++++++++++
    checkpoint/restart.c | 197 ++++++++++++++++++++++++++++++++++++++++
    checkpoint/sys.c | 194 ++++++++++++++++++++++++++++++++++++++-
    include/linux/checkpoint.h | 55 +++++++++++
    include/linux/checkpoint_hdr.h | 75 +++++++++++++++
    include/linux/magic.h | 3 +
    8 files changed, 693 insertions(+), 6 deletions(-)
    create mode 100644 checkpoint/checkpoint.c
    create mode 100644 checkpoint/restart.c
    create mode 100644 include/linux/checkpoint.h
    create mode 100644 include/linux/checkpoint_hdr.h

    diff --git a/Makefile b/Makefile
    index 29abe62..90dc50f 100644
    --- a/Makefile
    +++ b/Makefile
    @@ -619,7 +619,7 @@ export mod_strip_cmd


    ifeq ($(KBUILD_EXTMOD),)
    -core-y += kernel/ mm/ fs/ ipc/ security/ crypto/ block/
    +core-y += kernel/ mm/ fs/ ipc/ security/ crypto/ block/ checkpoint/

    vmlinux-dirs := $(patsubst %/,%,$(filter %/, $(init-y) $(init-m) \
    $(core-y) $(core-m) $(drivers-y) $(drivers-m) \
    diff --git a/checkpoint/Makefile b/checkpoint/Makefile
    index 07d018b..d2df68c 100644
    --- a/checkpoint/Makefile
    +++ b/checkpoint/Makefile
    @@ -2,4 +2,4 @@
    # Makefile for linux checkpoint/restart.
    #

    -obj-$(CONFIG_CHECKPOINT_RESTART) += sys.o
    +obj-$(CONFIG_CHECKPOINT_RESTART) += sys.o checkpoint.o restart.o
    diff --git a/checkpoint/checkpoint.c b/checkpoint/checkpoint.c
    new file mode 100644
    index 0000000..71f761e
    --- /dev/null
    +++ b/checkpoint/checkpoint.c
    @@ -0,0 +1,171 @@
    +/*
    + * Checkpoint logic and helpers
    + *
    + * Copyright (C) 2008 Oren Laadan
    + *
    + * This file is subject to the terms and conditions of the GNU General Public
    + * License. See the file COPYING in the main directory of the Linux
    + * distribution for more details.
    + */
    +
    +#include
    +#include
    +#include
    +#include
    +#include
    +#include
    +#include
    +#include
    +#include
    +#include
    +#include
    +
    +/* unique checkpoint identifier (FIXME: should be per-container ?) */
    +static atomic_t cr_ctx_count = ATOMIC_INIT(0);
    +
    +/**
    + * cr_write_obj - write a record described by a cr_hdr
    + * @ctx: checkpoint context
    + * @h: record descriptor
    + * @buf: record buffer
    + */
    +int cr_write_obj(struct cr_ctx *ctx, struct cr_hdr *h, void *buf)
    +{
    + int ret;
    +
    + ret = cr_kwrite(ctx, h, sizeof(*h));
    + if (ret < 0)
    + return ret;
    + return cr_kwrite(ctx, buf, h->len);
    +}
    +
    +/**
    + * cr_write_string - write a string
    + * @ctx: checkpoint context
    + * @str: string pointer
    + * @len: string length
    + */
    +int cr_write_string(struct cr_ctx *ctx, char *str, int len)
    +{
    + struct cr_hdr h;
    +
    + h.type = CR_HDR_STRING;
    + h.len = len;
    + h.parent = 0;
    +
    + return cr_write_obj(ctx, &h, str);
    +}
    +
    +/* write the checkpoint header */
    +static int cr_write_head(struct cr_ctx *ctx)
    +{
    + struct cr_hdr h;
    + struct cr_hdr_head *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + struct new_utsname *uts;
    + struct timeval ktv;
    + int ret;
    +
    + h.type = CR_HDR_HEAD;
    + h.len = sizeof(*hh);
    + h.parent = 0;
    +
    + do_gettimeofday(&ktv);
    +
    + hh->magic = CHECKPOINT_MAGIC_HEAD;
    + hh->major = (LINUX_VERSION_CODE >> 16) & 0xff;
    + hh->minor = (LINUX_VERSION_CODE >> 8) & 0xff;
    + hh->patch = (LINUX_VERSION_CODE) & 0xff;
    +
    + hh->rev = CR_VERSION;
    +
    + hh->flags = ctx->flags;
    + hh->time = ktv.tv_sec;
    +
    + uts = utsname();
    + memcpy(hh->release, uts->release, __NEW_UTS_LEN);
    + memcpy(hh->version, uts->version, __NEW_UTS_LEN);
    + memcpy(hh->machine, uts->machine, __NEW_UTS_LEN);
    +
    + ret = cr_write_obj(ctx, &h, hh);
    + cr_hbuf_put(ctx, sizeof(*hh));
    + return ret;
    +}
    +
    +/* write the checkpoint trailer */
    +static int cr_write_tail(struct cr_ctx *ctx)
    +{
    + struct cr_hdr h;
    + struct cr_hdr_tail *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + int ret;
    +
    + h.type = CR_HDR_TAIL;
    + h.len = sizeof(*hh);
    + h.parent = 0;
    +
    + hh->magic = CHECKPOINT_MAGIC_TAIL;
    +
    + ret = cr_write_obj(ctx, &h, hh);
    + cr_hbuf_put(ctx, sizeof(*hh));
    + return ret;
    +}
    +
    +/* dump the task_struct of a given task */
    +static int cr_write_task_struct(struct cr_ctx *ctx, struct task_struct *t)
    +{
    + struct cr_hdr h;
    + struct cr_hdr_task *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + int ret;
    +
    + h.type = CR_HDR_TASK;
    + h.len = sizeof(*hh);
    + h.parent = 0;
    +
    + hh->state = t->state;
    + hh->exit_state = t->exit_state;
    + hh->exit_code = t->exit_code;
    + hh->exit_signal = t->exit_signal;
    +
    + hh->task_comm_len = TASK_COMM_LEN;
    +
    + /* FIXME: save remaining relevant task_struct fields */
    +
    + ret = cr_write_obj(ctx, &h, hh);
    + cr_hbuf_put(ctx, sizeof(*hh));
    + if (ret < 0)
    + return ret;
    +
    + return cr_write_string(ctx, t->comm, TASK_COMM_LEN);
    +}
    +
    +/* dump the entire state of a given task */
    +static int cr_write_task(struct cr_ctx *ctx, struct task_struct *t)
    +{
    + int ret;
    +
    + ret = cr_write_task_struct(ctx, t);
    + cr_debug("ret %d\n", ret);
    +
    + return ret;
    +}
    +
    +int do_checkpoint(struct cr_ctx *ctx, pid_t pid)
    +{
    + int ret;
    +
    + ret = cr_write_head(ctx);
    + if (ret < 0)
    + goto out;
    + ret = cr_write_task(ctx, current);
    + if (ret < 0)
    + goto out;
    + ret = cr_write_tail(ctx);
    + if (ret < 0)
    + goto out;
    +
    + ctx->crid = atomic_inc_return(&cr_ctx_count);
    +
    + /* on success, return (unique) checkpoint identifier */
    + ret = ctx->crid;
    + out:
    + return ret;
    +}
    diff --git a/checkpoint/restart.c b/checkpoint/restart.c
    new file mode 100644
    index 0000000..fbfa52e
    --- /dev/null
    +++ b/checkpoint/restart.c
    @@ -0,0 +1,197 @@
    +/*
    + * Restart logic and helpers
    + *
    + * Copyright (C) 2008 Oren Laadan
    + *
    + * This file is subject to the terms and conditions of the GNU General Public
    + * License. See the file COPYING in the main directory of the Linux
    + * distribution for more details.
    + */
    +
    +#include
    +#include
    +#include
    +#include
    +#include
    +#include
    +
    +/**
    + * cr_read_obj - read a whole record (cr_hdr followed by payload)
    + * @ctx: checkpoint context
    + * @h: record descriptor
    + * @buf: record buffer
    + * @n: available buffer size
    + *
    + * Returns size of payload
    + */
    +int cr_read_obj(struct cr_ctx *ctx, struct cr_hdr *h, void *buf, int n)
    +{
    + int ret;
    +
    + ret = cr_kread(ctx, h, sizeof(*h));
    + if (ret < 0)
    + return ret;
    +
    + cr_debug("type %d len %d parent %d\n", h->type, h->len, h->parent);
    +
    + if (h->len < 0 || h->len > n)
    + return -EINVAL;
    +
    + return cr_kread(ctx, buf, h->len);
    +}
    +
    +/**
    + * cr_read_obj_type - read a whole record of expected type
    + * @ctx: checkpoint context
    + * @buf: record buffer
    + * @n: available buffer size
    + * @type: expected record type
    + *
    + * Returns object reference of the parent object
    + */
    +int cr_read_obj_type(struct cr_ctx *ctx, void *buf, int n, int type)
    +{
    + struct cr_hdr h;
    + int ret;
    +
    + ret = cr_read_obj(ctx, &h, buf, n);
    + if (ret < 0)
    + return ret;
    +
    + ret = -EINVAL;
    + if (h.type == type)
    + ret = h.parent;
    +
    + return ret;
    +}
    +
    +/**
    + * cr_read_string - read a string
    + * @ctx: checkpoint context
    + * @str: string buffer
    + * @len: buffer buffer length
    + */
    +int cr_read_string(struct cr_ctx *ctx, void *str, int len)
    +{
    + return cr_read_obj_type(ctx, str, len, CR_HDR_STRING);
    +}
    +
    +/* read the checkpoint header */
    +static int cr_read_head(struct cr_ctx *ctx)
    +{
    + struct cr_hdr_head *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + int parent, ret = -EINVAL;
    +
    + parent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_HEAD);
    + if (parent < 0) {
    + ret = parent;
    + goto out;
    + } else if (parent != 0)
    + goto out;
    +
    + if (hh->magic != CHECKPOINT_MAGIC_HEAD || hh->rev != CR_VERSION ||
    + hh->major != ((LINUX_VERSION_CODE >> 16) & 0xff) ||
    + hh->minor != ((LINUX_VERSION_CODE >> 8) & 0xff) ||
    + hh->patch != ((LINUX_VERSION_CODE) & 0xff))
    + goto out;
    +
    + if (hh->flags & ~CR_CTX_CKPT)
    + goto out;
    +
    + ctx->oflags = hh->flags;
    +
    + /* FIX: verify compatibility of release, version and machine */
    +
    + ret = 0;
    + out:
    + cr_hbuf_put(ctx, sizeof(*hh));
    + return ret;
    +}
    +
    +/* read the checkpoint trailer */
    +static int cr_read_tail(struct cr_ctx *ctx)
    +{
    + struct cr_hdr_tail *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + int parent, ret = -EINVAL;
    +
    + parent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_TAIL);
    + if (parent < 0) {
    + ret = parent;
    + goto out;
    + } else if (parent != 0)
    + goto out;
    +
    + if (hh->magic != CHECKPOINT_MAGIC_TAIL)
    + goto out;
    +
    + ret = 0;
    + out:
    + cr_hbuf_put(ctx, sizeof(*hh));
    + return ret;
    +}
    +
    +/* read the task_struct into the current task */
    +static int cr_read_task_struct(struct cr_ctx *ctx)
    +{
    + struct cr_hdr_task *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + struct task_struct *t = current;
    + char *buf;
    + int parent, ret = -EINVAL;
    +
    + parent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_TASK);
    + if (parent < 0) {
    + ret = parent;
    + goto out;
    + } else if (parent != 0)
    + goto out;
    +
    + /* upper limit for task_comm_len to prevent DoS */
    + if (hh->task_comm_len < 0 || hh->task_comm_len > PAGE_SIZE)
    + goto out;
    +
    + buf = kmalloc(hh->task_comm_len, GFP_KERNEL);
    + if (!buf)
    + goto out;
    + ret = cr_read_string(ctx, buf, hh->task_comm_len);
    + if (!ret) {
    + /* if t->comm is too long, silently truncate */
    + memset(t->comm, 0, TASK_COMM_LEN);
    + memcpy(t->comm, buf, min(hh->task_comm_len, TASK_COMM_LEN));
    + }
    + kfree(buf);
    +
    + /* FIXME: restore remaining relevant task_struct fields */
    + out:
    + cr_hbuf_put(ctx, sizeof(*hh));
    + return ret;
    +}
    +
    +/* read the entire state of the current task */
    +static int cr_read_task(struct cr_ctx *ctx)
    +{
    + int ret;
    +
    + ret = cr_read_task_struct(ctx);
    + cr_debug("ret %d\n", ret);
    +
    + return ret;
    +}
    +
    +int do_restart(struct cr_ctx *ctx, pid_t pid)
    +{
    + int ret;
    +
    + ret = cr_read_head(ctx);
    + if (ret < 0)
    + goto out;
    + ret = cr_read_task(ctx);
    + if (ret < 0)
    + goto out;
    + ret = cr_read_tail(ctx);
    + if (ret < 0)
    + goto out;
    +
    + /* on success, adjust the return value if needed [TODO] */
    + out:
    + return ret;
    +}
    diff --git a/checkpoint/sys.c b/checkpoint/sys.c
    index 375129c..bd14ef9 100644
    --- a/checkpoint/sys.c
    +++ b/checkpoint/sys.c
    @@ -10,6 +10,158 @@

    #include
    #include
    +#include
    +#include
    +#include
    +#include
    +#include
    +
    +/*
    + * Helpers to write(read) from(to) kernel space to(from) the checkpoint
    + * image file descriptor (similar to how a core-dump is performed).
    + *
    + * cr_kwrite() - write a kernel-space buffer to the checkpoint image
    + * cr_kread() - read from the checkpoint image to a kernel-space buffer
    + */
    +
    +int cr_kwrite(struct cr_ctx *ctx, void *addr, int count)
    +{
    + struct file *file = ctx->file;
    + mm_segment_t fs;
    + ssize_t nwrite;
    + int nleft;
    +
    + fs = get_fs();
    + set_fs(KERNEL_DS);
    + for (nleft = count; nleft; nleft -= nwrite) {
    + nwrite = file->f_op->write(file, addr, nleft, &file->f_pos);
    + if (nwrite < 0) {
    + if (nwrite == -EAGAIN)
    + nwrite = 0;
    + else
    + return nwrite;
    + }
    + addr += nwrite;
    + }
    + set_fs(fs);
    + ctx->total += count;
    + return 0;
    +}
    +
    +int cr_kread(struct cr_ctx *ctx, void *addr, int count)
    +{
    + struct file *file = ctx->file;
    + mm_segment_t fs;
    + ssize_t nread;
    + int nleft;
    +
    + fs = get_fs();
    + set_fs(KERNEL_DS);
    + for (nleft = count; nleft; nleft -= nread) {
    + nread = file->f_op->read(file, addr, nleft, &file->f_pos);
    + if (nread <= 0) {
    + if (nread == -EAGAIN) {
    + nread = 0;
    + continue;
    + } else if (nread == 0)
    + nread = -EPIPE; /* unexecpted EOF */
    + return nread;
    + }
    + addr += nread;
    + }
    + set_fs(fs);
    + ctx->total += count;
    + return 0;
    +}
    +
    +/*
    + * During checkpoint and restart the code writes outs/reads in data
    + * to/from the checkpoint image from/to a temporary buffer (ctx->hbuf).
    + * Because operations can be nested, use cr_hbuf_get() to reserve space
    + * in the buffer, then cr_hbuf_put() when you no longer need that space.
    + */
    +
    +/*
    + * ctx->hbuf is used to hold headers and data of known (or bound),
    + * static sizes. In some cases, multiple headers may be allocated in
    + * a nested manner. The size should accommodate all headers, nested
    + * or not, on all archs.
    + */
    +#define CR_HBUF_TOTAL (8 * 4096)
    +
    +/**
    + * cr_hbuf_get - reserve space on the hbuf
    + * @ctx: checkpoint context
    + * @n: number of bytes to reserve
    + *
    + * Returns pointer to reserved space
    + */
    +void *cr_hbuf_get(struct cr_ctx *ctx, int n)
    +{
    + void *ptr;
    +
    + /*
    + * Since requests depend on logic and static header sizes (not on
    + * user data), space should always suffice, unless someone either
    + * made a structure bigger or call path deeper than expected.
    + */
    + BUG_ON(ctx->hpos + n > CR_HBUF_TOTAL);
    + ptr = ctx->hbuf + ctx->hpos;
    + ctx->hpos += n;
    + return ptr;
    +}
    +
    +/**
    + * cr_hbuf_put - unreserve space on the hbuf
    + * @ctx: checkpoint context
    + * @n: number of bytes to reserve
    + */
    +void cr_hbuf_put(struct cr_ctx *ctx, int n)
    +{
    + BUG_ON(ctx->hpos < n);
    + ctx->hpos -= n;
    +}
    +
    +/*
    + * helpers to manage C/R contexts: allocated for each checkpoint and/or
    + * restart operation, and persists until the operation is completed.
    + */
    +
    +static void cr_ctx_free(struct cr_ctx *ctx)
    +{
    + if (ctx->file)
    + fput(ctx->file);
    + kfree(ctx->hbuf);
    + kfree(ctx);
    +}
    +
    +static struct cr_ctx *cr_ctx_alloc(int fd, unsigned long flags)
    +{
    + struct cr_ctx *ctx;
    + int err;
    +
    + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
    + if (!ctx)
    + return ERR_PTR(-ENOMEM);
    +
    + ctx->flags = flags;
    +
    + err = -EBADF;
    + ctx->file = fget(fd);
    + if (!ctx->file)
    + goto err;
    +
    + err = -ENOMEM;
    + ctx->hbuf = kmalloc(CR_HBUF_TOTAL, GFP_KERNEL);
    + if (!ctx->hbuf)
    + goto err;
    +
    + return ctx;
    +
    + err:
    + cr_ctx_free(ctx);
    + return ERR_PTR(err);
    +}

    /**
    * sys_checkpoint - checkpoint a container
    @@ -22,9 +174,26 @@
    */
    asmlinkage long sys_checkpoint(pid_t pid, int fd, unsigned long flags)
    {
    - pr_debug("sys_checkpoint not implemented yet\n");
    - return -ENOSYS;
    + struct cr_ctx *ctx;
    + int ret;
    +
    + /* no flags for now */
    + if (flags)
    + return -EINVAL;
    +
    + ctx = cr_ctx_alloc(fd, flags | CR_CTX_CKPT);
    + if (IS_ERR(ctx))
    + return PTR_ERR(ctx);
    +
    + ret = do_checkpoint(ctx, pid);
    +
    + if (!ret)
    + ret = ctx->crid;
    +
    + cr_ctx_free(ctx);
    + return ret;
    }
    +
    /**
    * sys_restart - restart a container
    * @crid: checkpoint image identifier
    @@ -36,6 +205,23 @@ asmlinkage long sys_checkpoint(pid_t pid, int fd, unsigned long flags)
    */
    asmlinkage long sys_restart(int crid, int fd, unsigned long flags)
    {
    - pr_debug("sys_restart not implemented yet\n");
    - return -ENOSYS;
    + struct cr_ctx *ctx;
    + pid_t pid;
    + int ret;
    +
    + /* no flags for now */
    + if (flags)
    + return -EINVAL;
    +
    + ctx = cr_ctx_alloc(fd, flags | CR_CTX_RSTR);
    + if (IS_ERR(ctx))
    + return PTR_ERR(ctx);
    +
    + /* FIXME: for now, we use 'crid' as a pid */
    + pid = (pid_t) crid;
    +
    + ret = do_restart(ctx, pid);
    +
    + cr_ctx_free(ctx);
    + return ret;
    }
    diff --git a/include/linux/checkpoint.h b/include/linux/checkpoint.h
    new file mode 100644
    index 0000000..9c119ba
    --- /dev/null
    +++ b/include/linux/checkpoint.h
    @@ -0,0 +1,55 @@
    +#ifndef _CHECKPOINT_CKPT_H_
    +#define _CHECKPOINT_CKPT_H_
    +/*
    + * Generic container checkpoint-restart
    + *
    + * Copyright (C) 2008 Oren Laadan
    + *
    + * This file is subject to the terms and conditions of the GNU General Public
    + * License. See the file COPYING in the main directory of the Linux
    + * distribution for more details.
    + */
    +
    +#define CR_VERSION 1
    +
    +struct cr_ctx {
    + int crid; /* unique checkpoint id */
    +
    + pid_t root_pid; /* container identifier */
    +
    + unsigned long flags;
    + unsigned long oflags; /* restart: old flags */
    +
    + struct file *file;
    + int total; /* total read/written */
    +
    + void *hbuf; /* temporary buffer for headers */
    + int hpos; /* position in headers buffer */
    +};
    +
    +/* cr_ctx: flags */
    +#define CR_CTX_CKPT 0x1
    +#define CR_CTX_RSTR 0x2
    +
    +extern int cr_kwrite(struct cr_ctx *ctx, void *buf, int count);
    +extern int cr_kread(struct cr_ctx *ctx, void *buf, int count);
    +
    +extern void *cr_hbuf_get(struct cr_ctx *ctx, int n);
    +extern void cr_hbuf_put(struct cr_ctx *ctx, int n);
    +
    +struct cr_hdr;
    +
    +extern int cr_write_obj(struct cr_ctx *ctx, struct cr_hdr *h, void *buf);
    +extern int cr_write_string(struct cr_ctx *ctx, char *str, int len);
    +
    +extern int cr_read_obj(struct cr_ctx *ctx, struct cr_hdr *h, void *buf, int n);
    +extern int cr_read_obj_type(struct cr_ctx *ctx, void *buf, int n, int type);
    +extern int cr_read_string(struct cr_ctx *ctx, void *str, int len);
    +
    +extern int do_checkpoint(struct cr_ctx *ctx, pid_t pid);
    +extern int do_restart(struct cr_ctx *ctx, pid_t pid);
    +
    +#define cr_debug(fmt, args...) \
    + pr_debug("[%d:c/r:%s] " fmt, task_pid_vnr(current), __func__, ## args)
    +
    +#endif /* _CHECKPOINT_CKPT_H_ */
    diff --git a/include/linux/checkpoint_hdr.h b/include/linux/checkpoint_hdr.h
    new file mode 100644
    index 0000000..79e4df2
    --- /dev/null
    +++ b/include/linux/checkpoint_hdr.h
    @@ -0,0 +1,75 @@
    +#ifndef _CHECKPOINT_CKPT_HDR_H_
    +#define _CHECKPOINT_CKPT_HDR_H_
    +/*
    + * Generic container checkpoint-restart
    + *
    + * Copyright (C) 2008 Oren Laadan
    + *
    + * This file is subject to the terms and conditions of the GNU General Public
    + * License. See the file COPYING in the main directory of the Linux
    + * distribution for more details.
    + */
    +
    +#include
    +#include
    +
    +/*
    + * To maintain compatibility between 32-bit and 64-bit architecture flavors,
    + * keep data 64-bit aligned: use padding for structure members, and use
    + * __attribute__ ((aligned (8))) for the entire structure.
    + */
    +
    +/* records: generic header */
    +
    +struct cr_hdr {
    + __s16 type;
    + __s16 len;
    + __u32 parent;
    +};
    +
    +/* header types */
    +enum {
    + CR_HDR_HEAD = 1,
    + CR_HDR_STRING,
    +
    + CR_HDR_TASK = 101,
    + CR_HDR_THREAD,
    + CR_HDR_CPU,
    +
    + CR_HDR_MM = 201,
    + CR_HDR_VMA,
    + CR_HDR_MM_CONTEXT,
    +
    + CR_HDR_TAIL = 5001
    +};
    +
    +struct cr_hdr_head {
    + __u64 magic;
    +
    + __u16 major;
    + __u16 minor;
    + __u16 patch;
    + __u16 rev;
    +
    + __u64 time; /* when checkpoint taken */
    + __u64 flags; /* checkpoint options */
    +
    + char release[__NEW_UTS_LEN];
    + char version[__NEW_UTS_LEN];
    + char machine[__NEW_UTS_LEN];
    +} __attribute__((aligned(8)));
    +
    +struct cr_hdr_tail {
    + __u64 magic;
    +} __attribute__((aligned(8)));
    +
    +struct cr_hdr_task {
    + __u32 state;
    + __u32 exit_state;
    + __u32 exit_code;
    + __u32 exit_signal;
    +
    + __s32 task_comm_len;
    +} __attribute__((aligned(8)));
    +
    +#endif /* _CHECKPOINT_CKPT_HDR_H_ */
    diff --git a/include/linux/magic.h b/include/linux/magic.h
    index f7f3fdd..5939bbe 100644
    --- a/include/linux/magic.h
    +++ b/include/linux/magic.h
    @@ -46,4 +46,7 @@
    #define FUTEXFS_SUPER_MAGIC 0xBAD1DEA
    #define INOTIFYFS_SUPER_MAGIC 0x2BAD1DEA

    +#define CHECKPOINT_MAGIC_HEAD 0x00feed0cc0a2d200LL
    +#define CHECKPOINT_MAGIC_TAIL 0x002d2a0cc0deef00LL
    +
    #endif /* __LINUX_MAGIC_H__ */
    --
    1.5.4.3

    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

  12. [RFC v9][PATCH 11/13] Track in-kernel when we expect checkpoint/restart to work

    From: Dave Hansen

    Suggested by Ingo.

    Checkpoint/restart is going to be a long effort to get things working.
    We're going to have a lot of things that we know just don't work for
    a long time. That doesn't mean that it will be useless, it just means
    that there's some complicated features that we are going to have to
    work incrementally to fix.

    This patch introduces a new mechanism to help the checkpoint/restart
    developers. A new function pair: task/process_deny_checkpoint() is
    created. When called, these tell the kernel that we *know* that the
    process has performed some activity that will keep it from being
    properly checkpointed.

    The 'flag' is an atomic_t for now so that we can have some level
    of atomicity and make sure to only warn once.

    For now, this is a one-way trip. Once a process is no longer
    'may_checkpoint' capable, neither it nor its children ever will be.
    This can, of course, be fixed up in the future. We might want to
    reset the flag when a new pid namespace is created, for instance.

    Signed-off-by: Dave Hansen
    Signed-off-by: Oren Laadan
    ---
    checkpoint/checkpoint.c | 6 ++++++
    include/linux/checkpoint.h | 33 ++++++++++++++++++++++++++++++++-
    include/linux/sched.h | 3 +++
    kernel/fork.c | 10 ++++++++++
    4 files changed, 51 insertions(+), 1 deletions(-)

    diff --git a/checkpoint/checkpoint.c b/checkpoint/checkpoint.c
    index a20f961..dd9f325 100644
    --- a/checkpoint/checkpoint.c
    +++ b/checkpoint/checkpoint.c
    @@ -213,6 +213,12 @@ static int cr_write_task(struct cr_ctx *ctx, struct task_struct *t)
    return -EAGAIN;
    }

    + if (!atomic_read(&task->may_checkpoint)) {
    + pr_warning("c/r: task %d may not checkpoint\n",
    + task_pid_vnr(task));
    + return -BUSY;
    + }
    +
    ret = cr_write_task_struct(ctx, t);
    cr_debug("task_struct: ret %d\n", ret);
    if (ret < 0)
    diff --git a/include/linux/checkpoint.h b/include/linux/checkpoint.h
    index b807e85..74a8597 100644
    --- a/include/linux/checkpoint.h
    +++ b/include/linux/checkpoint.h
    @@ -10,8 +10,11 @@
    * distribution for more details.
    */

    -#include
    #include
    +#include
    +#include
    +
    +#ifdef CONFIG_CHECKPOINT_RESTART

    #define CR_VERSION 2

    @@ -91,4 +94,32 @@ extern int cr_read_files(struct cr_ctx *ctx);
    #define cr_debug(fmt, args...) \
    pr_debug("[%d:c/r:%s] " fmt, task_pid_vnr(current), __func__, ## args)

    +static inline void __task_deny_checkpointing(struct task_struct *task,
    + char *file, int line)
    +{
    + if (!atomic_dec_and_test(&task->may_checkpoint))
    + return;
    + printk(KERN_INFO "process performed an action that can not be "
    + "checkpointed at: %s:%d\n", file, line);
    + WARN_ON(1);
    +}
    +#define process_deny_checkpointing(p) \
    + __task_deny_checkpointing(p, __FILE__, __LINE__)
    +
    +/*
    + * For now, we're not going to have a distinction between
    + * tasks and processes for the purpose of c/r. But, allow
    + * these two calls anyway to make new users at least think
    + * about it.
    + */
    +#define task_deny_checkpointing(p) \
    + __task_deny_checkpointing(p, __FILE__, __LINE__)
    +
    +#else
    +
    +static inline void task_deny_checkpointing(struct task_struct *task) {}
    +static inline void process_deny_checkpointing(struct task_struct *task) {}
    +
    +#endif
    +
    #endif /* _CHECKPOINT_CKPT_H_ */
    diff --git a/include/linux/sched.h b/include/linux/sched.h
    index b483f39..0c8d02d 100644
    --- a/include/linux/sched.h
    +++ b/include/linux/sched.h
    @@ -1349,6 +1349,9 @@ struct task_struct {
    */
    unsigned long timer_slack_ns;
    unsigned long default_timer_slack_ns;
    +#ifdef CONFIG_CHECKPOINT_RESTART
    + atomic_t may_checkpoint;
    +#endif
    };

    /*
    diff --git a/kernel/fork.c b/kernel/fork.c
    index f608356..693b0cb 100644
    --- a/kernel/fork.c
    +++ b/kernel/fork.c
    @@ -195,6 +195,13 @@ void __init fork_init(unsigned long mempages)
    init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
    init_task.signal->rlim[RLIMIT_SIGPENDING] =
    init_task.signal->rlim[RLIMIT_NPROC];
    +
    +#ifdef CONFIG_CHECKPOINT_RESTART
    + /*
    + * This probably won't stay set for long...
    + */
    + atomic_set(&init_task.may_checkpoint, 1);
    +#endif
    }

    int __attribute__((weak)) arch_dup_task_struct(struct task_struct *dst,
    @@ -245,6 +252,9 @@ static struct task_struct *dup_task_struct(struct task_struct *orig)
    tsk->btrace_seq = 0;
    #endif
    tsk->splice_pipe = NULL;
    +#ifdef CONFIG_CHECKPOINT_RESTART
    + atomic_set(&tsk->may_checkpoint, atomic_read(&orig->may_checkpoint));
    +#endif
    return tsk;

    out:
    --
    1.5.4.3

    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

  13. [RFC v9][PATCH 13/13] Restart multiple processes

    Restarting of multiple processes expects all restarting tasks to call
    sys_restart(). Once inside the system call, each task will restart
    itself at the same order that they were saved. The internals of the
    syscall will take care of in-kernel synchronization bewteen tasks.

    This patch does _not_ create the task tree in the kernel. Instead it
    assumes that all tasks are created in some way and then invoke the
    restart syscall. You can use the userspace mktree.c program to do
    that.

    The init task (*) has a special role: it allocates the resart context
    (ctx), and coordinates the operation. In particular, it first waits
    until all participating tasks enter the kernel, and provides them the
    common restart context. Once everyone in ready, it begins to restart
    itself.

    In contrast, the other tasks enter the kernel, locate the init task (*)
    and grab its restart context, and then wait for their turn to restore.

    When a task (init or not) completes its restart, it hands the control
    over to the next in line, by waking that task.

    An array of pids (the one saved during the checkpoint) is used to
    synchronize the operation. The first task in the array is the init
    task (*). The restart context (ctx) maintain a "current position" in
    the array, which indicates which task is currently active. Once the
    currently active task completes its own restart, it increments that
    position and wakes up the next task.

    Restart assumes that userspace provides meaningful data, otherwise
    it's garbage-in-garbage-out. In this case, the syscall may block
    indefinitely, but in TASK_INTERRUPTIBLE, so the user can ctrl-c or
    otherwise kill the stray restarting tasks.

    In terms of security, restart runs as the user the invokes it, so it
    will not allow a user to do more than is otherwise permitted by the
    usual system semantics and policy.

    Currently we ignore threads and zombies, as well as session ids.
    Add support for multiple processes

    (*) For containers, restart should be called inside a fresh container
    by the init task of that container. However, it is also possible to
    restart applications not necsesarily inside a container, and without
    restoring the original pids of the processes (that is, provided that
    the application can tolerate such behavior). This is useful to allow
    multi-process restart of tasks not isolated inside a container, and
    also for debugging.

    Signed-off-by: Oren Laadan
    ---
    checkpoint/restart.c | 216 +++++++++++++++++++++++++++++++++++++++++++-
    checkpoint/sys.c | 34 ++++++--
    include/linux/checkpoint.h | 23 ++++-
    include/linux/sched.h | 1 +
    4 files changed, 260 insertions(+), 14 deletions(-)

    diff --git a/checkpoint/restart.c b/checkpoint/restart.c
    index 8bd9d4a..5360c40 100644
    --- a/checkpoint/restart.c
    +++ b/checkpoint/restart.c
    @@ -10,6 +10,7 @@

    #include
    #include
    +#include
    #include
    #include
    #include
    @@ -234,30 +235,237 @@ static int cr_read_task(struct cr_ctx *ctx)
    return ret;
    }

    +/* cr_read_tree - read the tasks tree into the checkpoint context */
    +static int cr_read_tree(struct cr_ctx *ctx)
    +{
    + struct cr_hdr_tree *hh = cr_hbuf_get(ctx, sizeof(*hh));
    + int parent, size, ret = -EINVAL;
    +
    + parent = cr_read_obj_type(ctx, hh, sizeof(*hh), CR_HDR_TREE);
    + if (parent < 0) {
    + ret = parent;
    + goto out;
    + } else if (parent != 0)
    + goto out;
    +
    + if (hh->tasks_nr < 0)
    + goto out;
    +
    + ctx->pids_nr = hh->tasks_nr;
    + size = sizeof(*ctx->pids_arr) * ctx->pids_nr;
    + if (size < 0) /* overflow ? */
    + goto out;
    +
    + ctx->pids_arr = kmalloc(size, GFP_KERNEL);
    + if (!ctx->pids_arr) {
    + ret = -ENOMEM;
    + goto out;
    + }
    + ret = cr_kread(ctx, ctx->pids_arr, size);
    + out:
    + cr_hbuf_put(ctx, sizeof(*hh));
    + return ret;
    +}
    +
    +static int cr_wait_task(struct cr_ctx *ctx)
    +{
    + pid_t pid = task_pid_vnr(current);
    +
    + cr_debug("pid %d waiting\n", pid);
    + return wait_event_interruptible(ctx->waitq, ctx->pids_active == pid);
    +}
    +
    +static int cr_next_task(struct cr_ctx *ctx)
    +{
    + struct task_struct *tsk;
    +
    + ctx->pids_pos++;
    +
    + cr_debug("pids_pos %d %d\n", ctx->pids_pos, ctx->pids_nr);
    + if (ctx->pids_pos == ctx->pids_nr) {
    + complete(&ctx->complete);
    + return 0;
    + }
    +
    + ctx->pids_active = ctx->pids_arr[ctx->pids_pos].vpid;
    +
    + cr_debug("pids_next %d\n", ctx->pids_active);
    +
    + rcu_read_lock();
    + tsk = find_task_by_pid_ns(ctx->pids_active, ctx->root_nsproxy->pid_ns);
    + if (tsk)
    + wake_up_process(tsk);
    + rcu_read_unlock();
    +
    + if (!tsk) {
    + ctx->pids_err = -ESRCH;
    + complete(&ctx->complete);
    + return -ESRCH;
    + }
    +
    + return 0;
    +}
    +
    +/* FIXME: this should be per container */
    +DECLARE_WAIT_QUEUE_HEAD(cr_restart_waitq);
    +
    +#define SIG_KERNEL_ONLY_MASK (rt_sigmask(SIGKILL) | rt_sigmask(SIGSTOP))
    +
    +static int do_restart_task(struct cr_ctx *ctx, pid_t pid)
    +{
    + struct task_struct *root_task;
    + int ret;
    +
    + rcu_read_lock();
    + root_task = find_task_by_pid_ns(pid, current->nsproxy->pid_ns);
    + if (root_task)
    + get_task_struct(root_task);
    + rcu_read_unlock();
    +
    + if (!root_task)
    + return -EINVAL;
    +
    + /*
    + * wait for container init to initailize the restart context, then
    + * grab a reference to that context, and if we're the last task to
    + * do it, notify the container init.
    + */
    + ret = wait_event_interruptible(cr_restart_waitq,
    + root_task->checkpoint_ctx);
    + if (ret < 0)
    + goto out;
    +
    + task_lock(root_task);
    + ctx = root_task->checkpoint_ctx;
    + if (ctx)
    + cr_ctx_get(ctx);
    + task_unlock(root_task);
    +
    + if (!ctx) {
    + ret = -EAGAIN;
    + goto out;
    + }
    +
    + if (atomic_dec_and_test(&ctx->tasks_count))
    + complete(&ctx->complete);
    +
    + /* wait for our turn, do the restore, and tell next task in line */
    + ret = cr_wait_task(ctx);
    + if (ret < 0)
    + goto out;
    + ret = cr_read_task(ctx);
    + if (ret < 0)
    + goto out;
    + ret = cr_next_task(ctx);
    +
    + out:
    + cr_ctx_put(ctx);
    + put_task_struct(root_task);
    + return ret;
    +}
    +
    +static int cr_wait_all_tasks_start(struct cr_ctx *ctx)
    +{
    + int ret;
    +
    + if (ctx->pids_nr == 1)
    + return 0;
    +
    + init_completion(&ctx->complete);
    + current->checkpoint_ctx = ctx;
    +
    + wake_up_all(&cr_restart_waitq);
    +
    + ret = wait_for_completion_interruptible(&ctx->complete);
    + if (ret < 0)
    + return ret;
    +
    + task_lock(current);
    + current->checkpoint_ctx = NULL;
    + task_unlock(current);
    +
    + return 0;
    +}
    +
    +static int cr_wait_all_tasks_finish(struct cr_ctx *ctx)
    +{
    + int ret;
    +
    + if (ctx->pids_nr == 1)
    + return 0;
    +
    + init_completion(&ctx->complete);
    +
    + ret = cr_next_task(ctx);
    + if (ret < 0)
    + return ret;
    +
    + ret = wait_for_completion_interruptible(&ctx->complete);
    + if (ret < 0)
    + return ret;
    +
    + return 0;
    +}
    +
    /* setup restart-specific parts of ctx */
    static int cr_ctx_restart(struct cr_ctx *ctx, pid_t pid)
    {
    + ctx->root_pid = pid;
    + ctx->root_task = current;
    + ctx->root_nsproxy = current->nsproxy;
    +
    + get_task_struct(ctx->root_task);
    + get_nsproxy(ctx->root_nsproxy);
    +
    + atomic_set(&ctx->tasks_count, ctx->pids_nr - 1);
    +
    return 0;
    }

    -int do_restart(struct cr_ctx *ctx, pid_t pid)
    +static int do_restart_root(struct cr_ctx *ctx, pid_t pid)
    {
    int ret;

    + ret = cr_read_head(ctx);
    + if (ret < 0)
    + goto out;
    + ret = cr_read_tree(ctx);
    + if (ret < 0)
    + goto out;
    +
    ret = cr_ctx_restart(ctx, pid);
    if (ret < 0)
    goto out;
    - ret = cr_read_head(ctx);
    +
    + /* wait for all other tasks to enter do_restart_task() */
    + ret = cr_wait_all_tasks_start(ctx);
    if (ret < 0)
    goto out;
    +
    ret = cr_read_task(ctx);
    if (ret < 0)
    goto out;
    - ret = cr_read_tail(ctx);
    +
    + /* wait for all other tasks to complete do_restart_task() */
    + ret = cr_wait_all_tasks_finish(ctx);
    if (ret < 0)
    goto out;

    - /* on success, adjust the return value if needed [TODO] */
    + ret = cr_read_tail(ctx);
    +
    out:
    return ret;
    }
    +
    +int do_restart(struct cr_ctx *ctx, pid_t pid)
    +{
    + int ret;
    +
    + if (ctx)
    + ret = do_restart_root(ctx, pid);
    + else
    + ret = do_restart_task(ctx, pid);
    +
    + /* on success, adjust the return value if needed [TODO] */
    + return ret;
    +}
    diff --git a/checkpoint/sys.c b/checkpoint/sys.c
    index fbaf683..7745500 100644
    --- a/checkpoint/sys.c
    +++ b/checkpoint/sys.c
    @@ -145,6 +145,8 @@ static void cr_task_arr_free(struct cr_ctx *ctx)

    static void cr_ctx_free(struct cr_ctx *ctx)
    {
    + BUG_ON(atomic_read(&ctx->refcount));
    +
    if (ctx->file)
    fput(ctx->file);

    @@ -164,6 +166,8 @@ static void cr_ctx_free(struct cr_ctx *ctx)
    if (ctx->root_task)
    put_task_struct(ctx->root_task);

    + kfree(ctx->pids_arr);
    +
    kfree(ctx);
    }

    @@ -178,7 +182,9 @@ static struct cr_ctx *cr_ctx_alloc(int fd, unsigned long flags)

    ctx->flags = flags;

    + atomic_set(&ctx->refcount, 0);
    INIT_LIST_HEAD(&ctx->pgarr_list);
    + init_waitqueue_head(&ctx->waitq);

    err = -EBADF;
    ctx->file = fget(fd);
    @@ -193,6 +199,7 @@ static struct cr_ctx *cr_ctx_alloc(int fd, unsigned long flags)
    if (cr_objhash_alloc(ctx) < 0)
    goto err;

    + atomic_inc(&ctx->refcount);
    return ctx;

    err:
    @@ -200,6 +207,17 @@ static struct cr_ctx *cr_ctx_alloc(int fd, unsigned long flags)
    return ERR_PTR(err);
    }

    +void cr_ctx_get(struct cr_ctx *ctx)
    +{
    + atomic_inc(&ctx->refcount);
    +}
    +
    +void cr_ctx_put(struct cr_ctx *ctx)
    +{
    + if (ctx && atomic_dec_and_test(&ctx->refcount))
    + cr_ctx_free(ctx);
    +}
    +
    /**
    * sys_checkpoint - checkpoint a container
    * @pid: pid of the container init(1) process
    @@ -227,7 +245,7 @@ asmlinkage long sys_checkpoint(pid_t pid, int fd, unsigned long flags)
    if (!ret)
    ret = ctx->crid;

    - cr_ctx_free(ctx);
    + cr_ctx_put(ctx);
    return ret;
    }

    @@ -242,7 +260,7 @@ asmlinkage long sys_checkpoint(pid_t pid, int fd, unsigned long flags)
    */
    asmlinkage long sys_restart(int crid, int fd, unsigned long flags)
    {
    - struct cr_ctx *ctx;
    + struct cr_ctx *ctx = NULL;
    pid_t pid;
    int ret;

    @@ -250,15 +268,17 @@ asmlinkage long sys_restart(int crid, int fd, unsigned long flags)
    if (flags)
    return -EINVAL;

    - ctx = cr_ctx_alloc(fd, flags | CR_CTX_RSTR);
    - if (IS_ERR(ctx))
    - return PTR_ERR(ctx);
    -
    /* FIXME: for now, we use 'crid' as a pid */
    pid = (pid_t) crid;

    + if (pid == task_pid_vnr(current))
    + ctx = cr_ctx_alloc(fd, flags | CR_CTX_RSTR);
    +
    + if (IS_ERR(ctx))
    + return PTR_ERR(ctx);
    +
    ret = do_restart(ctx, pid);

    - cr_ctx_free(ctx);
    + cr_ctx_put(ctx);
    return ret;
    }
    diff --git a/include/linux/checkpoint.h b/include/linux/checkpoint.h
    index b142171..cab5e19 100644
    --- a/include/linux/checkpoint.h
    +++ b/include/linux/checkpoint.h
    @@ -13,10 +13,11 @@
    #include
    #include
    #include
    +#include

    #ifdef CONFIG_CHECKPOINT_RESTART

    -#define CR_VERSION 2
    +#define CR_VERSION 3

    struct cr_ctx {
    int crid; /* unique checkpoint id */
    @@ -34,14 +35,27 @@ struct cr_ctx {
    void *hbuf; /* temporary buffer for headers */
    int hpos; /* position in headers buffer */

    - struct task_struct **tasks_arr; /* array of all tasks in container */
    - int tasks_nr; /* size of tasks array */
    + atomic_t refcount;

    struct cr_objhash *objhash; /* hash for shared objects */

    struct list_head pgarr_list; /* page array to dump VMA contents */

    struct path *vfsroot; /* container root (FIXME) */
    +
    + /* [multi-process checkpoint] */
    + struct task_struct **tasks_arr; /* array of all tasks [checkpoint] */
    + int tasks_nr; /* size of tasks array */
    +
    + /* [multi-process restart] */
    + struct cr_hdr_pids *pids_arr; /* array of all pids [restart] */
    + int pids_nr; /* size of pids array */
    + int pids_pos; /* position pids array */
    + int pids_err; /* error occured ? */
    + pid_t pids_active; /* pid of (next) active task */
    + atomic_t tasks_count; /* sync of restarting tasks */
    + struct completion complete; /* sync of restarting tasks */
    + wait_queue_head_t waitq; /* sync of restarting tasks */
    };

    /* cr_ctx: flags */
    @@ -54,6 +68,9 @@ extern int cr_kread(struct cr_ctx *ctx, void *buf, int count);
    extern void *cr_hbuf_get(struct cr_ctx *ctx, int n);
    extern void cr_hbuf_put(struct cr_ctx *ctx, int n);

    +extern void cr_ctx_get(struct cr_ctx *ctx);
    +extern void cr_ctx_put(struct cr_ctx *ctx);
    +
    /* shared objects handling */

    enum {
    diff --git a/include/linux/sched.h b/include/linux/sched.h
    index 0c8d02d..cb39066 100644
    --- a/include/linux/sched.h
    +++ b/include/linux/sched.h
    @@ -1351,6 +1351,7 @@ struct task_struct {
    unsigned long default_timer_slack_ns;
    #ifdef CONFIG_CHECKPOINT_RESTART
    atomic_t may_checkpoint;
    + struct cr_ctx *checkpoint_ctx;
    #endif
    };

    --
    1.5.4.3

    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

  14. Re: [RFC v9][PATCH 05/13] Dump memory address space

    Quoting Oren Laadan (orenl@cs.columbia.edu):
    > +/**
    > + * cr_fill_fname - return pathname of a given file
    > + * @path: path name
    > + * @root: relative root
    > + * @buf: buffer for pathname
    > + * @n: buffer length (in) and pathname length (out)
    > + */
    > +static char *
    > +cr_fill_fname(struct path *path, struct path *root, char *buf, int *n)
    > +{
    > + struct path tmp = *root;
    > + char *fname;
    > +
    > + BUG_ON(!buf);
    > + fname = __d_path(path, &tmp, buf, *n);
    > + if (!IS_ERR(fname))
    > + *n = (buf + (*n) - fname);
    > + /*
    > + * FIXME: if __d_path() changed these, it must have stepped out of
    > + * init's namespace. Since currently we require a unified namespace
    > + * within the container: simply fail.
    > + */
    > + if (tmp.mnt != root->mnt || tmp.dentry != root->dentry)
    > + fname = ERR_PTR(-EBADF);
    > +
    > + return fname;
    > +}


    You still are not taking the dcache_lock around __d_path.

    -serge
    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

  15. Re: [RFC v9][PATCH 05/13] Dump memory address space



    Serge E. Hallyn wrote:
    > Quoting Oren Laadan (orenl@cs.columbia.edu):
    >> +/**
    >> + * cr_fill_fname - return pathname of a given file
    >> + * @path: path name
    >> + * @root: relative root
    >> + * @buf: buffer for pathname
    >> + * @n: buffer length (in) and pathname length (out)
    >> + */
    >> +static char *
    >> +cr_fill_fname(struct path *path, struct path *root, char *buf, int *n)
    >> +{
    >> + struct path tmp = *root;
    >> + char *fname;
    >> +
    >> + BUG_ON(!buf);
    >> + fname = __d_path(path, &tmp, buf, *n);
    >> + if (!IS_ERR(fname))
    >> + *n = (buf + (*n) - fname);
    >> + /*
    >> + * FIXME: if __d_path() changed these, it must have stepped out of
    >> + * init's namespace. Since currently we require a unified namespace
    >> + * within the container: simply fail.
    >> + */
    >> + if (tmp.mnt != root->mnt || tmp.dentry != root->dentry)
    >> + fname = ERR_PTR(-EBADF);
    >> +
    >> + return fname;
    >> +}

    >
    > You still are not taking the dcache_lock around __d_path.
    >


    You still are right.

    Oren.
    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

  16. Re: [RFC v9][PATCH 05/13] Dump memory address space

    Quoting Oren Laadan (orenl@cs.columbia.edu):
    > +/**
    > + * cr_fill_fname - return pathname of a given file
    > + * @path: path name
    > + * @root: relative root
    > + * @buf: buffer for pathname
    > + * @n: buffer length (in) and pathname length (out)
    > + */
    > +static char *
    > +cr_fill_fname(struct path *path, struct path *root, char *buf, int *n)
    > +{
    > + struct path tmp = *root;
    > + char *fname;
    > +
    > + BUG_ON(!buf);
    > + fname = __d_path(path, &tmp, buf, *n);
    > + if (!IS_ERR(fname))
    > + *n = (buf + (*n) - fname);
    > + /*
    > + * FIXME: if __d_path() changed these, it must have stepped out of
    > + * init's namespace. Since currently we require a unified namespace
    > + * within the container: simply fail.
    > + */
    > + if (tmp.mnt != root->mnt || tmp.dentry != root->dentry)
    > + fname = ERR_PTR(-EBADF);


    ....

    > +static int cr_ctx_checkpoint(struct cr_ctx *ctx, pid_t pid)
    > +{
    > + ctx->root_pid = pid;
    > +
    > + /*
    > + * assume checkpointer is in container's root vfs
    > + * FIXME: this works for now, but will change with real containers
    > + */
    > + ctx->vfsroot = &current->fs->root;
    > + path_get(ctx->vfsroot);


    Hi Oren,

    Is there really any good reason to use current->fs->root rather
    than ctx->root_task->fs->root here?

    The way I'm testing, the checkpointer is in fact in a different
    container, so the root passed into cr_fill_fname() is different
    from the container's root, so cr_fill_fname() always returns me
    -EBADF.

    thanks,
    -serge
    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

  17. Re: [RFC v9][PATCH 05/13] Dump memory address space



    Serge E. Hallyn wrote:
    > Quoting Oren Laadan (orenl@cs.columbia.edu):
    >> +/**
    >> + * cr_fill_fname - return pathname of a given file
    >> + * @path: path name
    >> + * @root: relative root
    >> + * @buf: buffer for pathname
    >> + * @n: buffer length (in) and pathname length (out)
    >> + */
    >> +static char *
    >> +cr_fill_fname(struct path *path, struct path *root, char *buf, int *n)
    >> +{
    >> + struct path tmp = *root;
    >> + char *fname;
    >> +
    >> + BUG_ON(!buf);
    >> + fname = __d_path(path, &tmp, buf, *n);
    >> + if (!IS_ERR(fname))
    >> + *n = (buf + (*n) - fname);
    >> + /*
    >> + * FIXME: if __d_path() changed these, it must have stepped out of
    >> + * init's namespace. Since currently we require a unified namespace
    >> + * within the container: simply fail.
    >> + */
    >> + if (tmp.mnt != root->mnt || tmp.dentry != root->dentry)
    >> + fname = ERR_PTR(-EBADF);

    >
    > ...
    >
    >> +static int cr_ctx_checkpoint(struct cr_ctx *ctx, pid_t pid)
    >> +{
    >> + ctx->root_pid = pid;
    >> +
    >> + /*
    >> + * assume checkpointer is in container's root vfs
    >> + * FIXME: this works for now, but will change with real containers
    >> + */
    >> + ctx->vfsroot = &current->fs->root;
    >> + path_get(ctx->vfsroot);

    >
    > Hi Oren,
    >
    > Is there really any good reason to use current->fs->root rather
    > than ctx->root_task->fs->root here?


    Oops, that's a leftover from before supporting external checkpoint.
    Will fix.

    >
    > The way I'm testing, the checkpointer is in fact in a different
    > container, so the root passed into cr_fill_fname() is different
    > from the container's root, so cr_fill_fname() always returns me
    > -EBADF.
    >


    Thanks,

    Oren.
    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

+ Reply to Thread