Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752795AbZKQNPe (ORCPT ); Tue, 17 Nov 2009 08:15:34 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752676AbZKQNPe (ORCPT ); Tue, 17 Nov 2009 08:15:34 -0500 Received: from mx1.redhat.com ([209.132.183.28]:23585 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752095AbZKQNPd (ORCPT ); Tue, 17 Nov 2009 08:15:33 -0500 Date: Tue, 17 Nov 2009 13:15:28 +0000 From: Alasdair G Kergon To: KOSAKI Motohiro Cc: LKML , linux-mm , Andrew Morton , dm-devel@redhat.com Subject: Re: [PATCH 1/7] dm: use __GFP_HIGH instead PF_MEMALLOC Message-ID: <20091117131527.GB6644@agk-dp.fab.redhat.com> Mail-Followup-To: KOSAKI Motohiro , LKML , linux-mm , Andrew Morton , dm-devel@redhat.com References: <20091117161551.3DD4.A69D9226@jp.fujitsu.com> <20091117161616.3DD7.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20091117161616.3DD7.A69D9226@jp.fujitsu.com> Organization: Red Hat UK Ltd. Registered in England and Wales, number 03798903. Registered Office: Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE. User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1020 Lines: 22 On Tue, Nov 17, 2009 at 04:17:07PM +0900, KOSAKI Motohiro wrote: > Non MM subsystem must not use PF_MEMALLOC. Memory reclaim need few > memory, anyone must not prevent it. Otherwise the system cause > mysterious hang-up and/or OOM Killer invokation. This code is also on the critical path, for example, if you are swapping onto a dm device. (There are ways we could reduce its use further as not every dm ioctl needs to be on the critical path and the buffer size could be limited for the ioctls that do.) But what situations have been causing you trouble? The OOM killer must generally avoid killing userspace processes that suspend & resume dm devices, and there are tight restrictions on what those processes can do safely between suspending and resuming. Alasdair -- 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/