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Commit 9df10fb7 authored by Tetsuo Handa's avatar Tetsuo Handa Committed by Linus Torvalds
Browse files

oom_reaper: avoid pointless atomic_inc_not_zero usage. 

Since commit 36324a99 ("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: default avatarTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 491a1c65

mm/oom_kill.c

+1 −7
Original line number Diff line number Diff line
@@ -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)) {