Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030713AbWKOREe (ORCPT ); Wed, 15 Nov 2006 12:04:34 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030714AbWKOREe (ORCPT ); Wed, 15 Nov 2006 12:04:34 -0500 Received: from smtp.osdl.org ([65.172.181.4]:9608 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S1030713AbWKOREc (ORCPT ); Wed, 15 Nov 2006 12:04:32 -0500 Date: Wed, 15 Nov 2006 09:00:05 -0800 From: Andrew Morton To: Badari Pulavarty Cc: linux-mm , ext4 , lkml Subject: Re: pagefault in generic_file_buffered_write() causing deadlock Message-Id: <20061115090005.c9ec6db5.akpm@osdl.org> In-Reply-To: <1163606265.7662.8.camel@dyn9047017100.beaverton.ibm.com> References: <1163606265.7662.8.camel@dyn9047017100.beaverton.ibm.com> X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.17; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1066 Lines: 27 On Wed, 15 Nov 2006 07:57:45 -0800 Badari Pulavarty wrote: > We are looking at a customer situation (on 2.6.16-based distro) - where > system becomes almost useless while running some java & stress tests. > > Root cause seems to be taking a pagefault in generic_file_buffered_write > () after calling prepare_write. I am wondering > > 1) Why & How this can happen - since we made sure to fault the user > buffer before prepare write. When using writev() we only fault in the first segment of the iovec. If the second or succesive segment isn't mapped into pagetables we're vulnerable to the deadlock. > 2) If this is already fixed in current mainline (I can't see how). It was fixed in 2.6.17. You'll need 6527c2bdf1f833cc18e8f42bd97973d583e4aa83 and 81b0c8713385ce1b1b9058e916edcf9561ad76d6 - 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/