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From: Michal Hocko <mhocko@kernel.org>
To: Tejun Heo <tj@kernel.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	Andrew Morton <akpm@linux-foundation.org>,
	Mel Gorman <mgorman@suse.de>,
	linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm, memory_hotplug: do not back off draining pcp free pages from kworker context
Date: Tue, 19 Sep 2017 11:45:21 +0200	[thread overview]
Message-ID: <20170919094521.2vqcnqrx3q2h2axb@dhcp22.suse.cz> (raw)
In-Reply-To: <20170919033821.GR378890@devbig577.frc2.facebook.com>

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

WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko@kernel.org>
To: Tejun Heo <tj@kernel.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	Andrew Morton <akpm@linux-foundation.org>,
	Mel Gorman <mgorman@suse.de>,
	linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm, memory_hotplug: do not back off draining pcp free pages from kworker context
Date: Tue, 19 Sep 2017 11:45:21 +0200	[thread overview]
Message-ID: <20170919094521.2vqcnqrx3q2h2axb@dhcp22.suse.cz> (raw)
In-Reply-To: <20170919033821.GR378890@devbig577.frc2.facebook.com>

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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  reply	other threads:[~2017-09-19  9:45 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-28  9:33 [PATCH] mm, memory_hotplug: do not back off draining pcp free pages from kworker context Michal Hocko
2017-08-28  9:33 ` Michal Hocko
2017-08-28 22:33 ` Andrew Morton
2017-08-28 22:33   ` Andrew Morton
2017-08-29 11:20   ` Tetsuo Handa
2017-08-29 11:20     ` Tetsuo Handa
2017-08-29 11:28     ` Michal Hocko
2017-08-29 11:28       ` Michal Hocko
2017-08-31  5:33       ` Michal Hocko
2017-08-31  5:33         ` Michal Hocko
2017-09-19  3:38         ` Tejun Heo
2017-09-19  3:38           ` Tejun Heo
2017-09-19  9:45           ` Michal Hocko [this message]
2017-09-19  9:45             ` Michal Hocko
2017-09-19 18:57             ` Tejun Heo
2017-09-19 18:57               ` Tejun Heo
2017-08-29 13:53   ` Michal Hocko
2017-08-29 13:53     ` Michal Hocko

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