Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757826Ab0FOOFi (ORCPT ); Tue, 15 Jun 2010 10:05:38 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52546 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757787Ab0FOOFg (ORCPT ); Tue, 15 Jun 2010 10:05:36 -0400 Message-ID: <4C178868.2010002@redhat.com> Date: Tue, 15 Jun 2010 10:04:24 -0400 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100430 Fedora/3.0.4-2.fc12 Lightning/1.0b2pre Thunderbird/3.0.4 MIME-Version: 1.0 To: Mel Gorman CC: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Dave Chinner , Chris Mason , Nick Piggin , Johannes Weiner , Christoph Hellwig , KAMEZAWA Hiroyuki , Andrew Morton Subject: Re: [PATCH 12/12] vmscan: Do not writeback pages in direct reclaim References: <1276514273-27693-1-git-send-email-mel@csn.ul.ie> <1276514273-27693-13-git-send-email-mel@csn.ul.ie> <4C16A567.4080000@redhat.com> <20100615114510.GE26788@csn.ul.ie> <4C17815A.8080402@redhat.com> <20100615135928.GK26788@csn.ul.ie> In-Reply-To: <20100615135928.GK26788@csn.ul.ie> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1274 Lines: 32 On 06/15/2010 09:59 AM, Mel Gorman wrote: > On Tue, Jun 15, 2010 at 09:34:18AM -0400, Rik van Riel wrote: >> On 06/15/2010 07:45 AM, Mel Gorman wrote: >>>>> >>>>> +/* kswapd and memcg can writeback as they are unlikely to overflow stack */ >>>>> +static inline bool reclaim_can_writeback(struct scan_control *sc) >>>>> +{ >>>>> + return current_is_kswapd() || sc->mem_cgroup != NULL; >>>>> +} >> If direct reclaim can overflow the stack, so can direct >> memcg reclaim. That means this patch does not solve the >> stack overflow, while admitting that we do need the >> ability to get specific pages flushed to disk from the >> pageout code. >> > > What path is taken with memcg != NULL that could overflow the stack? I > couldn't spot one but mm/memcontrol.c is a bit tangled so finding all > its use cases is tricky. The critical path I had in mind though was > direct reclaim and for that path, memcg == NULL or did I miss something? mem_cgroup_hierarchical_reclaim -> try_to_free_mem_cgroup_pages -- All rights reversed -- 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/