From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753722AbbJWSV0 (ORCPT ); Fri, 23 Oct 2015 14:21:26 -0400 Received: from mail-pa0-f45.google.com ([209.85.220.45]:33009 "EHLO mail-pa0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753649AbbJWSVW (ORCPT ); Fri, 23 Oct 2015 14:21:22 -0400 Date: Sat, 24 Oct 2015 03:21:09 +0900 From: Tejun Heo To: Michal Hocko Cc: Christoph Lameter , Tetsuo Handa , 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: <20151023182109.GA14610@mtj.duckdns.org> References: <20151022140944.GA30579@mtj.duckdns.org> <20151022150623.GE26854@dhcp22.suse.cz> <20151022151528.GG30579@mtj.duckdns.org> <20151022153559.GF26854@dhcp22.suse.cz> <20151022153703.GA3899@mtj.duckdns.org> <20151022154922.GG26854@dhcp22.suse.cz> <20151022184226.GA19289@mtj.duckdns.org> <20151023083316.GB2410@dhcp22.suse.cz> <20151023103630.GA4170@mtj.duckdns.org> <20151023111145.GH2410@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151023111145.GH2410@dhcp22.suse.cz> 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 Hello, On Fri, Oct 23, 2015 at 01:11:45PM +0200, Michal Hocko wrote: > > The problem here is not lack > > of execution resource but concurrency management misunderstanding the > > situation. > > And this sounds like a bug to me. I don't know. I can be argued either way, the other direction being a kernel thread going RUNNING non-stop is buggy. Given how this has been a complete non-issue for all the years, I'm not sure how useful plugging this is. > Don't we have some IO related paths which would suffer from the same > problem. I haven't checked all the WQ_MEM_RECLAIM users but from the > name I would expect they _do_ participate in the reclaim and so they > should be able to make a progress. Now if your new IMMEDIATE flag will Seriously, nobody goes full-on RUNNING. > guarantee that then I would argue that it should be implicit for > WQ_MEM_RECLAIM otherwise we always risk a similar situation. What would > be a counter argument for doing that? Not serving any actual purpose and degrading execution behavior. Thanks. -- tejun