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Date: Wed, 1 Nov 2017 16:16:00 +0100 From: Michal Hocko <mhocko@...nel.org> To: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp> Cc: akpm@...ux-foundation.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org, rientjes@...gle.com, mjaggi@...iumnetworks.com, oleg@...hat.com, vdavydov@...tuozzo.com Subject: Re: [PATCH 2/2] mm,oom: Use ALLOC_OOM for OOM victim's last second allocation. On Thu 02-11-17 00:08:59, Tetsuo Handa wrote: > Michal Hocko wrote: [...] > > I am not sure about this part though. If the oom_reaper cannot take the > > mmap_sem then it retries for 1s. Have you ever seen the race to be that > > large? > > Like shown in [2], khugepaged can prevent oom_reaper from taking the mmap_sem > for 1 second. Also, it won't be impossible for OOM victims to spend 1 second > between post __gfp_pfmemalloc_flags(gfp_mask) and pre mutex_trylock(&oom_lock) > (in other words, the race window (1-2) above). Therefore, non artificial > workloads could hit the same result. but this is a speculation so I wouldn't mention it in the changelog. It might confuse readers. -- Michal Hocko SUSE Labs
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