From c38f1025f2910d6183e9923d4b4d5804474b50c5 Mon Sep 17 00:00:00 2001 From: Johannes Weiner <hannes@cmpxchg.org> Date: Wed, 24 Jun 2015 16:57:13 -0700 Subject: [PATCH] mm: oom_kill: generalize OOM progress waitqueue It turns out that the mechanism to wait for exiting OOM victims is less generic than it looks: it won't issue wakeups unless the OOM killer is disabled. The reason this check was added was the thought that, since only the OOM disabling code would wait on this queue, wakeup operations could be saved when that specific consumer is known to be absent. However, this is quite the handgrenade. Later attempts to reuse the waitqueue for other purposes will lead to completely unexpected bugs and the failure mode will appear seemingly illogical. Generally, providers shouldn't make unnecessary assumptions about consumers. This could have been replaced with waitqueue_active(), but it only saves a few instructions in one of the coldest paths in the kernel. Simply remove it. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: David Rientjes <rientjes@google.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> --- mm/oom_kill.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 4b9547be9170..472f124e5f08 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -438,11 +438,7 @@ void exit_oom_victim(void) clear_thread_flag(TIF_MEMDIE); down_read(&oom_sem); - /* - * There is no need to signal the lasst oom_victim if there - * is nobody who cares. - */ - if (!atomic_dec_return(&oom_victims) && oom_killer_disabled) + if (!atomic_dec_return(&oom_victims)) wake_up_all(&oom_victims_wait); up_read(&oom_sem); } -- GitLab