Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753532Ab0HYMxO (ORCPT ); Wed, 25 Aug 2010 08:53:14 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:44542 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752637Ab0HYMxL convert rfc822-to-8bit (ORCPT ); Wed, 25 Aug 2010 08:53:11 -0400 Subject: Re: [patch 1/5] mm: add nofail variants of kmalloc kcalloc and kzalloc From: Peter Zijlstra To: "Ted Ts'o" Cc: David Rientjes , Jens Axboe , Andrew Morton , Neil Brown , Alasdair G Kergon , Chris Mason , Steven Whitehouse , Jan Kara , Frederic Weisbecker , "linux-raid@vger.kernel.org" , "linux-btrfs@vger.kernel.org" , "cluster-devel@redhat.com" , "linux-ext4@vger.kernel.org" , "reiserfs-devel@vger.kernel.org" , "linux-kernel@vger.kernel.org" In-Reply-To: <1282740516.2605.3644.camel@laptop> References: <1282656558.2605.2742.camel@laptop> <4C73CA24.3060707@fusionio.com> <20100825112433.GB4453@thunk.org> <1282736132.2605.3563.camel@laptop> <20100825115709.GD4453@thunk.org> <1282740516.2605.3644.camel@laptop> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Wed, 25 Aug 2010 14:52:58 +0200 Message-ID: <1282740778.2605.3652.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1054 Lines: 25 On Wed, 2010-08-25 at 14:48 +0200, Peter Zijlstra wrote: > > > On Wed, 2010-08-25 at 07:24 -0400, Ted Ts'o wrote: > > > > (a) retry the loop in the jbd layer (which Andrew really doesn't > > > > like), (b) keep our own private cache of free memory so we don't fail > > > > and/or loop, > Well (b) sounds a lot saner than either of those. Simply revert to a > state that is sub-optimal but has bounded memory use and reserve that > memory up-front. That way you can always get out of a tight memory spot. Also, there's a good reason for disliking (a), its a deadlock scenario, suppose we need to write out data to get free pages, but the writing out is blocked on requiring free pages. There's really nothing the page allocator can do to help you there, its a situation you have to avoid getting into. -- 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/