From: Alan Cox

The atomic_t type is 32bit but a 64bit system can have more than 2^32
pages of virtual address space available. Without this we overflow on
ludicrously large mappings
---

fs/proc/proc_misc.c | 2 +-
include/linux/mman.h | 4 ++--
mm/mmap.c | 4 ++--
mm/nommu.c | 4 ++--
mm/swap.c | 4 ++--
5 files changed, 9 insertions(+), 9 deletions(-)


diff --git a/fs/proc/proc_misc.c b/fs/proc/proc_misc.c
index 74a323d..32dc14c 100644
--- a/fs/proc/proc_misc.c
+++ b/fs/proc/proc_misc.c
@@ -139,7 +139,7 @@ static int meminfo_read_proc(char *page, char **start, off_t off,
#define K(x) ((x) << (PAGE_SHIFT - 10))
si_meminfo(&i);
si_swapinfo(&i);
- committed = atomic_read(&vm_committed_space);
+ committed = atomic_long_read(&vm_committed_space);
allowed = ((totalram_pages - hugetlb_total_pages())
* sysctl_overcommit_ratio / 100) + total_swap_pages;

diff --git a/include/linux/mman.h b/include/linux/mman.h
index 87920a0..dab8892 100644
--- a/include/linux/mman.h
+++ b/include/linux/mman.h
@@ -17,14 +17,14 @@

extern int sysctl_overcommit_memory;
extern int sysctl_overcommit_ratio;
-extern atomic_t vm_committed_space;
+extern atomic_long_t vm_committed_space;

#ifdef CONFIG_SMP
extern void vm_acct_memory(long pages);
#else
static inline void vm_acct_memory(long pages)
{
- atomic_add(pages, &vm_committed_space);
+ atomic_long_add(pages, &vm_committed_space);
}
#endif

diff --git a/mm/mmap.c b/mm/mmap.c
index fac6633..669499e 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -80,7 +80,7 @@ EXPORT_SYMBOL(vm_get_page_prot);
int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
int sysctl_overcommit_ratio = 50; /* default is 50% */
int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
-atomic_t vm_committed_space = ATOMIC_INIT(0);
+atomic_long_t vm_committed_space = ATOMIC_LONG_INIT(0);

/*
* Check that a process has enough memory to allocate a new virtual
@@ -177,7 +177,7 @@ int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
* cast `allowed' as a signed long because vm_committed_space
* sometimes has a negative value
*/
- if (atomic_read(&vm_committed_space) < (long)allowed)
+ if (atomic_long_read(&vm_committed_space) < (long)allowed)
return 0;
error:
vm_unacct_memory(pages);
diff --git a/mm/nommu.c b/mm/nommu.c
index ef8c62c..dca93fc 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -39,7 +39,7 @@ struct page *mem_map;
unsigned long max_mapnr;
unsigned long num_physpages;
unsigned long askedalloc, realalloc;
-atomic_t vm_committed_space = ATOMIC_INIT(0);
+atomic_long_t vm_committed_space = ATOMIC_LONG_INIT(0);
int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
int sysctl_overcommit_ratio = 50; /* default is 50% */
int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
@@ -1410,7 +1410,7 @@ int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
* cast `allowed' as a signed long because vm_committed_space
* sometimes has a negative value
*/
- if (atomic_read(&vm_committed_space) < (long)allowed)
+ if (atomic_long_read(&vm_committed_space) < (long)allowed)
return 0;
error:
vm_unacct_memory(pages);
diff --git a/mm/swap.c b/mm/swap.c
index 91e1944..45c9f25 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -503,7 +503,7 @@ void vm_acct_memory(long pages)
local = &__get_cpu_var(committed_space);
*local += pages;
if (*local > ACCT_THRESHOLD || *local < -ACCT_THRESHOLD) {
- atomic_add(*local, &vm_committed_space);
+ atomic_long_add(*local, &vm_committed_space);
*local = 0;
}
preempt_enable();
@@ -520,7 +520,7 @@ static int cpu_swap_callback(struct notifier_block *nfb,

committed = &per_cpu(committed_space, (long)hcpu);
if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
- atomic_add(*committed, &vm_committed_space);
+ atomic_long_add(*committed, &vm_committed_space);
*committed = 0;
drain_cpu_pagevecs((long)hcpu);
}

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