On Sat 04-06-16 16:19:19, Tetsuo Handa wrote:
> Since commit 36324a990cf578b5 ("oom: clear TIF_MEMDIE after oom_reaper
> managed to unmap the address space") changed to use find_lock_task_mm()
> for finding a mm_struct to reap, it is guaranteed that mm->mm_users > 0
> because find_lock_task_mm() returns a task_struct with ->mm != NULL.
> Therefore, we can safely use atomic_inc().
>
> Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxx>
> Cc: Arnd Bergmann <arnd@xxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Thanks!
> ---
> mm/oom_kill.c | 7 +------
> 1 file changed, 1 insertion(+), 6 deletions(-)
>
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> index dfb1ab6..8050fa0 100644
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -474,13 +474,8 @@ static bool __oom_reap_task(struct task_struct *tsk)
> p = find_lock_task_mm(tsk);
> if (!p)
> goto unlock_oom;
> -
> mm = p->mm;
> - if (!atomic_inc_not_zero(&mm->mm_users)) {
> - task_unlock(p);
> - goto unlock_oom;
> - }
> -
> + atomic_inc(&mm->mm_users);
> task_unlock(p);
>
> if (!down_read_trylock(&mm->mmap_sem)) {
> --
> 1.8.3.1
>
--
Michal Hocko
SUSE Labs
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