Re: [PATCH] mm,vmscan: Use accurate values for zone_reclaimable() checks

From	Tejun Heo <htejun@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] mm,vmscan: Use accurate values for zone_reclaimable() checks
Date	2015-11-03 20:50 +0100
Message-ID	<qqPKF-76u-3@gated-at.bofh.it> (permalink)
References	(1 earlier) <qmpOO-6iz-29@gated-at.bofh.it> <qmC9j-7jL-1@gated-at.bofh.it> <qqoUa-6R3-21@gated-at.bofh.it> <qqsXM-No-7@gated-at.bofh.it> <qqzFT-50z-11@gated-at.bofh.it>
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Hello, Tetsuo.

On Tue, Nov 03, 2015 at 11:32:06AM +0900, Tetsuo Handa wrote:
> Tejun Heo wrote:
> >                                                                  If
> > the possibility of sysrq getting stuck behind concurrency management
> > is an issue, queueing them on an unbound or highpri workqueue should
> > be good enough.
> 
> Regarding SysRq-f, we could do like below. Though I think that converting
> the OOM killer into a dedicated kernel thread would allow more things to do
> (e.g. Oleg's memory zapping code, my timeout based next victim selection).

I'm not sure doing anything to sysrq-f is warranted.  If workqueue
can't make forward progress due to memory exhaustion, OOM will be
triggered anyway.  Getting stuck behind concurrency management isn't
that different a failure mode from getting stuck behind busy loop with
preemption off.  We should just plug them at the source.  If
necessary, what we can do is adding stall watchdog (can prolly
combined with the usual watchdog) so that it can better point out the
culprit.

Thanks.

-- 
tejun
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Thread

Re: [PATCH] mm,vmscan: Use accurate values for zone_reclaimable()  checks Michal Hocko <mhocko@kernel.org> - 2015-11-02 16:10 +0100
  Re: [PATCH] mm,vmscan: Use accurate values for zone_reclaimable()  checks Tejun Heo <htejun@gmail.com> - 2015-11-02 20:30 +0100
    Re: [PATCH] mm,vmscan: Use accurate values for zone_reclaimable() checks Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2015-11-03 03:40 +0100
      Re: [PATCH] mm,vmscan: Use accurate values for zone_reclaimable()  checks Tejun Heo <htejun@gmail.com> - 2015-11-03 20:50 +0100
  Re: [PATCH] mm,vmscan: Use accurate values for zone_reclaimable() checks Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2015-11-05 16:10 +0100
    Re: [PATCH] mm,vmscan: Use accurate values for zone_reclaimable()  checks Christoph Lameter <cl@linux.com> - 2015-11-05 18:50 +0100
      Re: [PATCH] mm,vmscan: Use accurate values for zone_reclaimable()  checks Tejun Heo <htejun@gmail.com> - 2015-11-06 01:20 +0100
        Re: [PATCH] mm,vmscan: Use accurate values for zone_reclaimable()  checks Michal Hocko <mhocko@kernel.org> - 2015-11-11 16:50 +0100
          Re: [PATCH] mm,vmscan: Use accurate values for zone_reclaimable()  checks Michal Hocko <mhocko@kernel.org> - 2015-11-11 17:10 +0100

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