[PATCH] sched: add sanity check in partition_sched_domains() - Kernel

This is a discussion on [PATCH] sched: add sanity check in partition_sched_domains() - Kernel ; It's wrong to make dattr_new = NULL if doms_new == NULL, it introduces memory leak if dattr_new != NULL. Fortunately dattr_new is always NULL in this case. So remove the code and add a sanity check. Signed-off-by: Li Zefan --- ...

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Thread: [PATCH] sched: add sanity check in partition_sched_domains()

  1. [PATCH] sched: add sanity check in partition_sched_domains()

    It's wrong to make dattr_new = NULL if doms_new == NULL, it introduces
    memory leak if dattr_new != NULL. Fortunately dattr_new is always NULL
    in this case. So remove the code and add a sanity check.

    Signed-off-by: Li Zefan
    ---
    kernel/sched.c | 2 +-
    1 files changed, 1 insertions(+), 1 deletions(-)

    diff --git a/kernel/sched.c b/kernel/sched.c
    index baa7e4b..0dcda75 100644
    --- a/kernel/sched.c
    +++ b/kernel/sched.c
    @@ -7787,7 +7787,7 @@ match1:
    ndoms_cur = 0;
    doms_new = &fallback_doms;
    cpus_andnot(doms_new[0], cpu_online_map, cpu_isolated_map);
    - dattr_new = NULL;
    + BUG_ON(dattr_new);
    }

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  2. Re: [PATCH] sched: add sanity check in partition_sched_domains()


    * Li Zefan wrote:

    > It's wrong to make dattr_new = NULL if doms_new == NULL, it introduces
    > memory leak if dattr_new != NULL. Fortunately dattr_new is always NULL
    > in this case. So remove the code and add a sanity check.
    >
    > Signed-off-by: Li Zefan
    > ---
    > kernel/sched.c | 2 +-
    > 1 files changed, 1 insertions(+), 1 deletions(-)


    applied to tip/sched/core, thanks!

    a small detail, i changed this:

    > + BUG_ON(dattr_new);


    to WARN_ON_ONCE().

    If there's a rare setup-time memory leak we dont want to crash the box
    via a BUG_ON(), as that only results in unhappy users. We want a
    WARN_ON_ONCE() so that we get nice bugreports and kerneloops.org
    coverage as well instead.

    We use BUG_ON() in new code only in the rarest of circumstances: if we
    absolutely want to bring down the box right there - because there's a
    serious risk of data corruption, security breach, etc.

    Ingo
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  3. Re: [PATCH] sched: add sanity check in partition_sched_domains()

    > a small detail, i changed this:
    >
    >> + BUG_ON(dattr_new);

    >
    > to WARN_ON_ONCE().
    >
    > If there's a rare setup-time memory leak we dont want to crash the box
    > via a BUG_ON(), as that only results in unhappy users. We want a
    > WARN_ON_ONCE() so that we get nice bugreports and kerneloops.org
    > coverage as well instead.
    >
    > We use BUG_ON() in new code only in the rarest of circumstances: if we
    > absolutely want to bring down the box right there - because there's a
    > serious risk of data corruption, security breach, etc.
    >


    I see the point, thx for the explanation.

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