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oom_reaper: avoid pointless atomic_inc_not_zero usage.

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Since commit 36324a990cf5 ("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().

Link: http://lkml.kernel.org/r/1465024759-8074-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Tetsuo Handa 2016-06-24 14:48:38 -07:00 committed by Linus Torvalds
parent 491a1c65ae
commit 9df10fb7b8
1 changed files with 1 additions and 7 deletions
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8
mm/oom_kill.c
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@ -474,14 +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);
mm = NULL;
goto unlock_oom;
}
atomic_inc(&mm->mm_users);
task_unlock(p);
if (!down_read_trylock(&mm->mmap_sem)) {