From 66b7a8b70ac0f5f99e6ad0d99eab86ac837146f7 Mon Sep 17 00:00:00 2001 From: Michal Hocko Date: Fri, 1 Apr 2016 14:31:34 -0700 Subject: [PATCH] oom, oom_reaper: do not enqueue task if it is on the oom_reaper_list head Commit 6e3e665f00ad ("oom, oom_reaper: protect oom_reaper_list using simpler way") has simplified the check for tasks already enqueued for the oom reaper by checking tsk->oom_reaper_list != NULL. This check is not sufficient because the tsk might be the head of the queue without any other tasks queued and then we would simply lockup looping on the same task. Fix the condition by checking for the head as well. Fixes: 6e3e665f00ad ("oom, oom_reaper: protect oom_reaper_list using simpler way") Signed-off-by: Michal Hocko Acked-by: Tetsuo Handa Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/oom_kill.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/mm/oom_kill.c b/mm/oom_kill.c index b34d279a7ee6c..86349586eacba 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -547,7 +547,11 @@ static int oom_reaper(void *unused) static void wake_oom_reaper(struct task_struct *tsk) { - if (!oom_reaper_th || tsk->oom_reaper_list) + if (!oom_reaper_th) + return; + + /* tsk is already queued? */ + if (tsk == oom_reaper_list || tsk->oom_reaper_list) return; get_task_struct(tsk); -- 2.39.5