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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next prev parent reply other threads:[~2017-07-11 0:01 UTC|newest]
Thread overview: 19+ 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
2017-06-27 10:52 ` Tetsuo Handa
2017-06-27 11:26 ` Michal Hocko
2017-06-27 11:39 ` Tetsuo Handa
2017-06-27 12:03 ` Michal Hocko
2017-06-27 13:31 ` Tetsuo Handa
2017-06-27 13:55 ` Michal Hocko
2017-06-27 14:26 ` Tetsuo Handa
2017-06-27 14:41 ` Michal Hocko
2017-07-11 0:01 ` David Rientjes [this message]
2017-06-29 8:46 ` Michal Hocko
2017-07-19 5:55 ` Michal Hocko
2017-07-20 1:18 ` Hugh Dickins
2017-07-20 13:05 ` Michal Hocko
2017-07-24 6:39 ` Hugh Dickins
2017-07-10 23:55 ` David Rientjes
2017-07-11 6:58 ` Michal Hocko
2017-07-11 20:40 ` David Rientjes
2017-07-12 7:12 ` Michal Hocko
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