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From: Michal Hocko <mhocko@kernel.org>
To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: akpm@linux-foundation.org, mgorman@suse.de, rientjes@google.com,
	torvalds@linux-foundation.org, oleg@redhat.com, hughd@google.com,
	andrea@kernel.org, riel@redhat.com, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH] sysrq: ensure manual invocation of the OOM killer under OOM livelock
Date: Tue, 5 Jan 2016 19:05:09 +0100	[thread overview]
Message-ID: <20160105180507.GB23326@dhcp22.suse.cz> (raw)
In-Reply-To: <20160105162246.GH15324@dhcp22.suse.cz>

On Tue 05-01-16 17:22:46, Michal Hocko wrote:
> On Wed 30-12-15 15:33:47, Tetsuo Handa wrote:
[...]
> > I wish for a kernel thread that does OOM-kill operation.
> > Maybe we can change the OOM reaper kernel thread to do it.
> > What do you think?
> 
> I do no think a separate kernel thread would help much if the
> allocations have to keep looping in the allocator. oom_reaper is a
> separate kernel thread only due to locking required for the exit_mmap
> path.

Let me clarify what I've meant here. What you actually want is to do
select_bad_process and oom_kill_process (including oom_reap_vmas) in
the kernel thread context, right? That should be doable because we do
not depend on the allocation context there. That would certainly save
1 kernel thread for the sysrq+f part but it would make the regular
case more complicated AFAICS. We would have to handle queuing of the
oom requests because multiple oom killers might be active in different
allocation domains (cpusets, memcgs) so I am not so sure this would be a
great win in the end. But I haven't tried to do it so I might be wrong
and it will turn up being much more easier than I expect.

-- 
Michal Hocko
SUSE Labs

WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko@kernel.org>
To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: akpm@linux-foundation.org, mgorman@suse.de, rientjes@google.com,
	torvalds@linux-foundation.org, oleg@redhat.com, hughd@google.com,
	andrea@kernel.org, riel@redhat.com, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH] sysrq: ensure manual invocation of the OOM killer under OOM livelock
Date: Tue, 5 Jan 2016 19:05:09 +0100	[thread overview]
Message-ID: <20160105180507.GB23326@dhcp22.suse.cz> (raw)
In-Reply-To: <20160105162246.GH15324@dhcp22.suse.cz>

On Tue 05-01-16 17:22:46, Michal Hocko wrote:
> On Wed 30-12-15 15:33:47, Tetsuo Handa wrote:
[...]
> > I wish for a kernel thread that does OOM-kill operation.
> > Maybe we can change the OOM reaper kernel thread to do it.
> > What do you think?
> 
> I do no think a separate kernel thread would help much if the
> allocations have to keep looping in the allocator. oom_reaper is a
> separate kernel thread only due to locking required for the exit_mmap
> path.

Let me clarify what I've meant here. What you actually want is to do
select_bad_process and oom_kill_process (including oom_reap_vmas) in
the kernel thread context, right? That should be doable because we do
not depend on the allocation context there. That would certainly save
1 kernel thread for the sysrq+f part but it would make the regular
case more complicated AFAICS. We would have to handle queuing of the
oom requests because multiple oom killers might be active in different
allocation domains (cpusets, memcgs) so I am not so sure this would be a
great win in the end. But I haven't tried to do it so I might be wrong
and it will turn up being much more easier than I expect.

-- 
Michal Hocko
SUSE Labs

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  parent reply	other threads:[~2016-01-05 18:05 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-12-30  6:33 [RFC][PATCH] sysrq: ensure manual invocation of the OOM killer under OOM livelock Tetsuo Handa
2015-12-30  6:33 ` Tetsuo Handa
2016-01-05 16:22 ` Michal Hocko
2016-01-05 16:22   ` Michal Hocko
2016-01-05 17:38   ` Michal Hocko
2016-01-05 17:38     ` Michal Hocko
2016-01-05 18:05   ` Michal Hocko [this message]
2016-01-05 18:05     ` Michal Hocko
2016-01-06 11:49     ` [RFC][PATCH] sysrq: ensure manual invocation of the OOM killerunder " Tetsuo Handa
2016-01-06 11:49       ` Tetsuo Handa
2016-01-06 13:17       ` Michal Hocko
2016-01-06 13:17         ` Michal Hocko

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