From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with ESMTP id AF5B26B01AD for ; Wed, 16 Jun 2010 01:07:06 -0400 (EDT) Date: Wed, 16 Jun 2010 01:06:40 -0400 From: Christoph Hellwig Subject: Re: [PATCH 12/12] vmscan: Do not writeback pages in direct reclaim Message-ID: <20100616050640.GA10687@infradead.org> 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> <4C178868.2010002@redhat.com> <20100615141601.GL26788@csn.ul.ie> <20100616091755.7121c7d3.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100616091755.7121c7d3.kamezawa.hiroyu@jp.fujitsu.com> Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: Mel Gorman , Rik van Riel , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Dave Chinner , Chris Mason , Nick Piggin , Johannes Weiner , Christoph Hellwig , Andrew Morton List-ID: On Wed, Jun 16, 2010 at 09:17:55AM +0900, KAMEZAWA Hiroyuki wrote: > yes. It's only called from > - page fault > - add_to_page_cache() > > I think we'll see no stack problem. Now, memcg doesn't wakeup kswapd for > reclaiming memory, it needs direct writeback. The page fault code should be fine, but add_to_page_cache can be called with quite deep stacks. Two examples are grab_cache_page_write_begin which already was part of one of the stack overflows mentioned in this thread, or find_or_create_page which can be called via _xfs_buf_lookup_pages, which can be called from under the whole XFS allocator, or via grow_dev_page which might have a similarly deep stack for users of the normal buffer cache. Although for the find_or_create_page we usually should not have __GFP_FS set in the gfp_mask. -- 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