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Re: [PATCH] mm, memory_hotplug: do not back off draining pcp free pages from kworker context

From Michal Hocko <mhocko@kernel.org>
Newsgroups linux.kernel
Subject Re: [PATCH] mm, memory_hotplug: do not back off draining pcp free pages from kworker context
Date 2017-09-19 11:50 +0200
Message-ID <urnkd-39c-3@gated-at.bofh.it> (permalink)
References (1 earlier) <ujARj-2QC-3@gated-at.bofh.it> <ujMSu-1Zf-21@gated-at.bofh.it> <ujMSu-1Zf-23@gated-at.bofh.it> <ukqmR-1y0-5@gated-at.bofh.it> <urhyb-7dq-9@gated-at.bofh.it>
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On Mon 18-09-17 20:38:22, Tejun Heo wrote:
> Hello, Sorry about the delay.
> 
> On Thu, Aug 31, 2017 at 07:33:42AM +0200, Michal Hocko wrote:
> > > > Michal, are you sure that this patch does not cause deadlock?
> > > > 
> > > > As shown in "[PATCH] mm: Use WQ_HIGHPRI for mm_percpu_wq." thread, currently work
> > > > items on mm_percpu_wq seem to be blocked by other work items not on mm_percpu_wq.
> 
> IIUC that wasn't a deadlock but more a legitimate starvation from too
> many tasks trying to reclaim directly.
> 
> > > But we have a rescuer so we should make a forward progress eventually.
> > > Or am I missing something. Tejun, could you have a look please?
> > 
> > ping... I would really appreaciate if you could double check my thinking
> > Tejun. This is a tricky area and I would like to prevent further subtle
> > issues here.
> 
> So, this shouldn't be an issue.  This may get affected by direct
> reclaim frenzy but it's only a small piece of the whole symptom and we
> gotta fix that at the source.

OK, so there shouldn't be any issue with the patch, right?
-- 
Michal Hocko
SUSE Labs

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Thread

Re: [PATCH] mm, memory_hotplug: do not back off draining pcp free  pages from kworker context Tejun Heo <tj@kernel.org> - 2017-09-19 05:40 +0200
  Re: [PATCH] mm, memory_hotplug: do not back off draining pcp free  pages from kworker context Michal Hocko <mhocko@kernel.org> - 2017-09-19 11:50 +0200
    Re: [PATCH] mm, memory_hotplug: do not back off draining pcp free  pages from kworker context Tejun Heo <tj@kernel.org> - 2017-09-19 21:00 +0200

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