From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx190.postini.com [74.125.245.190]) by kanga.kvack.org (Postfix) with SMTP id B1AE36B00B6 for ; Wed, 20 Jun 2012 05:55:53 -0400 (EDT) Date: Wed, 20 Jun 2012 17:55:46 +0800 From: Fengguang Wu Subject: Re: [PATCH -mm] memcg: prevent from OOM with too many dirty pages Message-ID: <20120620095546.GB8765@localhost> References: <1340117404-30348-1-git-send-email-mhocko@suse.cz> <20120619150014.1ebc108c.akpm@linux-foundation.org> <20120620092011.GB4011@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120620092011.GB4011@suse.de> Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: Andrew Morton , Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org, KAMEZAWA Hiroyuki , Minchan Kim , Rik van Riel , Ying Han , Greg Thelen , Hugh Dickins , Johannes Weiner > > Finally, I wonder if there should be some timeout of that wait. I > > don't know why, but I wouldn't be surprised if we hit some glitch which > > causes us to add one! > > > > If we hit such a situation it means that flush is no longer working which > is interesting in itself. I guess one possibility where it can occur is > if we hit global dirty limits (or memcg dirty limits when they exist) > and the page is backed by NFS that is disconnected. That would stall here > potentially forever but it's already the case that a system that hits its > dirty limits with a disconnected NFS is in trouble and a timeout here will > not do much to help. Agreed. I've run into such cases and cannot login even locally because the shell will be blocked trying to write even 1 byte at startup time. Any opened shells are also stalled on writing to .bash_history etc. Thanks, Fengguang -- 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