From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757727AbbJVOJx (ORCPT ); Thu, 22 Oct 2015 10:09:53 -0400 Received: from mail-pa0-f52.google.com ([209.85.220.52]:35722 "EHLO mail-pa0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756721AbbJVOJw (ORCPT ); Thu, 22 Oct 2015 10:09:52 -0400 Date: Thu, 22 Oct 2015 23:09:44 +0900 From: Tejun Heo To: Christoph Lameter Cc: Tetsuo Handa , mhocko@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, David Rientjes , oleg@redhat.com, kwalker@redhat.com, akpm@linux-foundation.org, hannes@cmpxchg.org, vdavydov@parallels.com, skozina@redhat.com, mgorman@suse.de, riel@redhat.com Subject: Re: [PATCH] mm,vmscan: Use accurate values for zone_reclaimable() checks Message-ID: <20151022140944.GA30579@mtj.duckdns.org> References: <20151021143337.GD8805@dhcp22.suse.cz> <20151021145505.GE8805@dhcp22.suse.cz> <201510222037.ACH86458.OFOLFtQFOHJSVM@I-love.SAKURA.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 22, 2015 at 08:39:11AM -0500, Christoph Lameter wrote: > On Thu, 22 Oct 2015, Tetsuo Handa wrote: > > > The problem would be that the "struct task_struct" to execute vmstat_update > > job does not exist, and will not be able to create one on demand because we > > are stuck at __GFP_WAIT allocation. Therefore adding a dedicated kernel > > thread for vmstat_update job would work. But ... > > Yuck. Can someone please get this major screwup out of the work queue > subsystem? Tejun? Hmmm? Just use a dedicated workqueue with WQ_MEM_RECLAIM. If concurrency management is a problem and there's something live-locking for that work item (really?), WQ_CPU_INTENSIVE escapes it. If this is a common occurrence that it makes sense to give vmstat higher priority, set WQ_HIGHPRI. Thanks. -- tejun