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Date: Sat, 28 Nov 2015 13:39:11 +0900 From: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp> To: mhocko@...nel.org, linux-mm@...ck.org Cc: akpm@...ux-foundation.org, torvalds@...ux-foundation.org, mgorman@...e.de, rientjes@...gle.com, riel@...hat.com, hughd@...gle.com, oleg@...hat.com, andrea@...nel.org, linux-kernel@...r.kernel.org, mhocko@...e.com Subject: Re: [RFC PATCH -v2] mm, oom: introduce oom reaper 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; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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