From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f70.google.com (mail-pg0-f70.google.com [74.125.83.70]) by kanga.kvack.org (Postfix) with ESMTP id C46C96B0033 for ; Tue, 19 Sep 2017 05:45:26 -0400 (EDT) Received: by mail-pg0-f70.google.com with SMTP id 11so5630944pge.4 for ; Tue, 19 Sep 2017 02:45:26 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id r16si1113223pfk.88.2017.09.19.02.45.25 for (version=TLS1 cipher=AES128-SHA bits=128/128); Tue, 19 Sep 2017 02:45:25 -0700 (PDT) Date: Tue, 19 Sep 2017 11:45:21 +0200 From: Michal Hocko Subject: Re: [PATCH] mm, memory_hotplug: do not back off draining pcp free pages from kworker context Message-ID: <20170919094521.2vqcnqrx3q2h2axb@dhcp22.suse.cz> References: <20170828093341.26341-1-mhocko@kernel.org> <20170828153359.f9b252f99647eebd339a3a89@linux-foundation.org> <6e138348-aa28-8660-d902-96efafe1dcb2@I-love.SAKURA.ne.jp> <20170829112823.GA12413@dhcp22.suse.cz> <20170831053342.fo7x4hnhicxikme4@dhcp22.suse.cz> <20170919033821.GR378890@devbig577.frc2.facebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170919033821.GR378890@devbig577.frc2.facebook.com> Sender: owner-linux-mm@kvack.org List-ID: To: Tejun Heo Cc: Tetsuo Handa , Andrew Morton , Mel Gorman , linux-mm@kvack.org, LKML 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org