Messages in this thread | | | Date | Mon, 3 Jun 2013 18:31:34 +0200 | From | Michal Hocko <> | Subject | Re: [patch] mm, memcg: add oom killer delay |
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On Sat 01-06-13 02:11:51, Johannes Weiner wrote: > @@ -2076,6 +2077,7 @@ static void memcg_wakeup_oom(struct mem_cgroup *memcg) > { > /* for filtering, pass "memcg" as argument. */ > __wake_up(&memcg_oom_waitq, TASK_NORMAL, 0, memcg); > + atomic_inc(&memcg->oom_wakeups); > } > > static void memcg_oom_recover(struct mem_cgroup *memcg) [...] > + prepare_to_wait(&memcg_oom_waitq, &owait.wait, TASK_KILLABLE); > + /* Only sleep if we didn't miss any wakeups since OOM */ > + if (atomic_read(&memcg->oom_wakeups) == current->memcg_oom.wakeups) > + schedule();
On the way home it occured to me that the ordering might be wrong here. The wake up can be lost here. __wake_up(memcg_oom_waitq) <preempted> prepare_to_wait atomic_read(&memcg->oom_wakeups) atomic_inc(oom_wakeups)
I guess we want atomic_inc before __wake_up, right? -- Michal Hocko SUSE Labs
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