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From: David Rientjes <rientjes@google.com>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: mhocko@kernel.org, linux-mm@kvack.org, oleg@redhat.com,
	andrea@kernel.org, akpm@linux-foundation.org,
	linux-kernel@vger.kernel.org, mhocko@suse.com
Subject: Re: [RFC PATCH] mm, oom: allow oom reaper to race with exit_mmap
Date: Mon, 10 Jul 2017 17:01:01 -0700 (PDT)	[thread overview]
Message-ID: <alpine.DEB.2.10.1707101659080.55253@chino.kir.corp.google.com> (raw)
In-Reply-To: <201706271952.FEB21375.SFJFHOQLOtVOMF@I-love.SAKURA.ne.jp>

On Tue, 27 Jun 2017, Tetsuo Handa wrote:

> I wonder why you prefer timeout based approach. Your patch will after all
> set MMF_OOM_SKIP if operations between down_write() and up_write() took
> more than one second. lock_anon_vma_root() from unlink_anon_vmas() from
> free_pgtables() for example calls down_write()/up_write(). unlink_file_vma()
>  from free_pgtables() for another example calls down_write()/up_write().
> This means that it might happen that exit_mmap() takes more than one second
> with mm->mmap_sem held for write, doesn't this?
> 

I certainly have no objection to increasing the timeout period or 
increasing MAX_OOM_REAP_RETRIES to be substantially higher.  All threads 
holding mm->mmap_sem should be oom killed and be able to access memory 
reserves to make forward progress if they fail to reclaim.  If we are 
truly blocked on mm->mmap_sem, waiting longer than one second to declare 
that seems justifiable to prevent the exact situation you describe.

WARNING: multiple messages have this Message-ID
From: David Rientjes <rientjes@google.com>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: mhocko@kernel.org, linux-mm@kvack.org, oleg@redhat.com,
	andrea@kernel.org, akpm@linux-foundation.org,
	linux-kernel@vger.kernel.org, mhocko@suse.com
Subject: Re: [RFC PATCH] mm, oom: allow oom reaper to race with exit_mmap
Date: Mon, 10 Jul 2017 17:01:01 -0700 (PDT)	[thread overview]
Message-ID: <alpine.DEB.2.10.1707101659080.55253@chino.kir.corp.google.com> (raw)
In-Reply-To: <201706271952.FEB21375.SFJFHOQLOtVOMF@I-love.SAKURA.ne.jp>

On Tue, 27 Jun 2017, Tetsuo Handa wrote:

> I wonder why you prefer timeout based approach. Your patch will after all
> set MMF_OOM_SKIP if operations between down_write() and up_write() took
> more than one second. lock_anon_vma_root() from unlink_anon_vmas() from
> free_pgtables() for example calls down_write()/up_write(). unlink_file_vma()
>  from free_pgtables() for another example calls down_write()/up_write().
> This means that it might happen that exit_mmap() takes more than one second
> with mm->mmap_sem held for write, doesn't this?
> 

I certainly have no objection to increasing the timeout period or 
increasing MAX_OOM_REAP_RETRIES to be substantially higher.  All threads 
holding mm->mmap_sem should be oom killed and be able to access memory 
reserves to make forward progress if they fail to reclaim.  If we are 
truly blocked on mm->mmap_sem, waiting longer than one second to declare 
that seems justifiable to prevent the exact situation you describe.

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  parent reply	other threads:[~2017-07-11  0:01 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-26 13:03 [RFC PATCH] mm, oom: allow oom reaper to race with exit_mmap Michal Hocko
2017-06-26 13:03 ` Michal Hocko
2017-06-27 10:52 ` Tetsuo Handa
2017-06-27 10:52   ` Tetsuo Handa
2017-06-27 11:26   ` Michal Hocko
2017-06-27 11:26     ` Michal Hocko
2017-06-27 11:39     ` Tetsuo Handa
2017-06-27 11:39       ` Tetsuo Handa
2017-06-27 12:03       ` Michal Hocko
2017-06-27 12:03         ` Michal Hocko
2017-06-27 13:31         ` Tetsuo Handa
2017-06-27 13:31           ` Tetsuo Handa
2017-06-27 13:55           ` Michal Hocko
2017-06-27 13:55             ` Michal Hocko
2017-06-27 14:26             ` Tetsuo Handa
2017-06-27 14:26               ` Tetsuo Handa
2017-06-27 14:41               ` Michal Hocko
2017-06-27 14:41                 ` Michal Hocko
2017-07-11  0:01   ` David Rientjes [this message]
2017-07-11  0:01     ` David Rientjes
2017-06-29  8:46 ` Michal Hocko
2017-06-29  8:46   ` Michal Hocko
2017-07-19  5:55   ` Michal Hocko
2017-07-19  5:55     ` Michal Hocko
2017-07-20  1:18     ` Hugh Dickins
2017-07-20  1:18       ` Hugh Dickins
2017-07-20 13:05       ` Michal Hocko
2017-07-20 13:05         ` Michal Hocko
2017-07-24  6:39         ` Hugh Dickins
2017-07-24  6:39           ` Hugh Dickins
2017-07-10 23:55 ` David Rientjes
2017-07-10 23:55   ` David Rientjes
2017-07-11  6:58   ` Michal Hocko
2017-07-11  6:58     ` Michal Hocko
2017-07-11 20:40     ` David Rientjes
2017-07-11 20:40       ` David Rientjes
2017-07-12  7:12       ` Michal Hocko
2017-07-12  7:12         ` Michal Hocko

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