From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rik van Riel Subject: Re: [PATCH 12/12] vmscan: Do not writeback pages in direct reclaim Date: Tue, 15 Jun 2010 10:04:24 -0400 Message-ID: <4C178868.2010002@redhat.com> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit 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 To: Mel Gorman Return-path: In-Reply-To: <20100615135928.GK26788@csn.ul.ie> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org 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, 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