mm,oom_reaper: don't call mmput_async() without atomic_inc_not_zero()

Tetsuo Handa · torvalds · commit 491a1c65ae49 · 2016-06-24T17:23:52.000-07:00
Commit e2fe145 ("oom_reaper: close race with exiting task") reduced frequency of needlessly selecting next OOM victim, but was calling mmput_async() when atomic_inc_not_zero() failed. Link: http://lkml.kernel.org/r/1464423365-5555-1-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>
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
@@ -478,6 +478,7 @@ static bool __oom_reap_task(struct task_struct *tsk)
 	mm = p->mm;
 	if (!atomic_inc_not_zero(&mm->mm_users)) {
 		task_unlock(p);
+		mm = NULL;
 		goto unlock_oom;
 	}
 

Original file line number	Diff line number	Diff line change
`@@ -478,6 +478,7 @@ static bool __oom_reap_task(struct task_struct *tsk)`
`478`	`478`	`mm = p->mm;`
`479`	`479`	`if (!atomic_inc_not_zero(&mm->mm_users)) {`
`480`	`480`	`task_unlock(p);`
	`481`	`+ mm = NULL;`
`481`	`482`	`goto unlock_oom;`
`482`	`483`	`}`
`483`	`484`