Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161410AbbKFM4b (ORCPT ); Fri, 6 Nov 2015 07:56:31 -0500 Received: from resqmta-ch2-08v.sys.comcast.net ([69.252.207.40]:48924 "EHLO resqmta-ch2-08v.sys.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932747AbbKFM4a (ORCPT ); Fri, 6 Nov 2015 07:56:30 -0500 Date: Fri, 6 Nov 2015 06:56:28 -0600 (CST) From: Christoph Lameter X-X-Sender: cl@east.gentwo.org To: Tetsuo Handa cc: htejun@gmail.com, akpm@linux-foundation.org, mhocko@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, hannes@cmpxchg.org, mgorman@suse.de Subject: Re: [patch 3/3] vmstat: Create our own workqueue In-Reply-To: <201511062028.DFE13506.MtVSOOFJLFOHQF@I-love.SAKURA.ne.jp> Message-ID: References: <20151029022447.GB27115@mtj.duckdns.org> <20151029030822.GD27115@mtj.duckdns.org> <201510311143.BIH87000.tOSVFHOFJMLFOQ@I-love.SAKURA.ne.jp> <201511062028.DFE13506.MtVSOOFJLFOHQF@I-love.SAKURA.ne.jp> Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1258 Lines: 30 On Fri, 6 Nov 2015, Tetsuo Handa wrote: > So, if you refer to the blocking of the execution of vmstat updates, > description for patch 3/3 sould be updated to something like below? Ok that is much better. > ---------- > Since __GFP_WAIT memory allocations do not call schedule() > when there is nothing to reclaim, and workqueue does not kick > remaining workqueue items unless in-flight workqueue item calls > schedule(), __GFP_WAIT memory allocation requests by workqueue > items can block vmstat_update work item forever. > > Since zone_reclaimable() decision depends on vmstat counters > to be up to dated, a silent lockup occurs because a workqueue > item doing a __GFP_WAIT memory allocation request continues > using outdated vmstat counters. > > In order to fix this problem, we need to allocate a dedicated > workqueue for vmstat. Note that this patch itself does not fix > lockup problem. Tejun will develop a patch which detects lockup > situation and kick remaining workqueue items. > ---------- > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/