Messages in this thread Patch in this message | | | Subject | Re: [RFC PATCH -v2] mm, oom: introduce oom reaper | From | Tetsuo Handa <> | Date | Sat, 28 Nov 2015 13:39:11 +0900 |
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Michal Hocko wrote: > for write while write but the probability is reduced considerably wrt.
Is this "while write" garbage?
> Users of mmap_sem which need it for write should be carefully reviewed > to use _killable waiting as much as possible and reduce allocations > requests done with the lock held to absolute minimum to reduce the risk > even further.
It will be nice if we can have down_write_killable()/down_read_killable().
> The API between oom killer and oom reaper is quite trivial. wake_oom_reaper > updates mm_to_reap with cmpxchg to guarantee only NUll->mm transition
NULL->mm
> and oom_reaper clear this atomically once it is done with the work.
Can't oom_reaper() become as compact as below?
diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 3f22efc..c2ab7f9 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -472,21 +472,10 @@ static void oom_reap_vmas(struct mm_struct *mm) static int oom_reaper(void *unused) { - DEFINE_WAIT(wait); - while (true) { - struct mm_struct *mm; - - prepare_to_wait(&oom_reaper_wait, &wait, TASK_UNINTERRUPTIBLE); - mm = READ_ONCE(mm_to_reap); - if (!mm) { - freezable_schedule(); - finish_wait(&oom_reaper_wait, &wait); - } else { - finish_wait(&oom_reaper_wait, &wait); - oom_reap_vmas(mm); - WRITE_ONCE(mm_to_reap, NULL); - } + wait_event_freezable(oom_reaper_wait, mm_to_reap); + oom_reap_vmas(mm_to_reap); + mm_to_reap = NULL; } return 0;
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