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>
---
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
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