Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757392Ab0FONf0 (ORCPT ); Tue, 15 Jun 2010 09:35:26 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54683 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752660Ab0FONfZ (ORCPT ); Tue, 15 Jun 2010 09:35:25 -0400 Message-ID: <4C17815A.8080402@redhat.com> Date: Tue, 15 Jun 2010 09:34:18 -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> In-Reply-To: <20100615114510.GE26788@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: 1489 Lines: 43 On 06/15/2010 07:45 AM, Mel Gorman wrote: > On Mon, Jun 14, 2010 at 05:55:51PM -0400, Rik van Riel wrote: >> On 06/14/2010 07:17 AM, Mel Gorman wrote: >> >>> diff --git a/mm/vmscan.c b/mm/vmscan.c >>> index 4856a2a..574e816 100644 >>> --- a/mm/vmscan.c >>> +++ b/mm/vmscan.c >>> @@ -372,6 +372,12 @@ int write_reclaim_page(struct page *page, struct address_space *mapping, >>> return PAGE_SUCCESS; >>> } >>> >>> +/* 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; >>> +} >>> + >> >> I'm not entirely convinced on this bit, but am willing to >> be convinced by the data. >> > > Which bit? > > You're not convinced that kswapd should be allowed to write back? > You're not convinced that memcg should be allowed to write back? > You're not convinced that direct reclaim writing back pages can overflow > the stack? 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. -- 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/