From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: [PATCH] Don't use unnecessary GFP_ATOMIC in sg.c Date: Mon, 25 Feb 2008 15:56:25 +0100 Message-ID: <20080225145625.GA16158@one.firstfloor.org> References: <20080224233632.GA31228@basil.nowhere.org> <1203950588.3254.12.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from one.firstfloor.org ([213.235.205.2]:55148 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754780AbYBYOzu (ORCPT ); Mon, 25 Feb 2008 09:55:50 -0500 Content-Disposition: inline In-Reply-To: <1203950588.3254.12.camel@localhost.localdomain> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: James Bottomley Cc: Andi Kleen , linux-scsi@vger.kernel.org On Mon, Feb 25, 2008 at 06:43:08AM -0800, James Bottomley wrote: > On Mon, 2008-02-25 at 00:36 +0100, Andi Kleen wrote: > > Don't use unnecessary GFP_ATOMIC in sg.c > > > > sg.c uses GFP_ATOMIC for a lot of allocations where it isn't necessary. > > There are no locks hold and I don't see any other reasons why GFP_ATOMIC > > should be needed here. So remove them for more reliable allocations. > > > > Depends on the earlier GFP_DMA patchkit, but only because it happens > > to patch the same places (no real functional dependency) > > > > Tested by burning a CD on a kernel with all lock/sleep/etc. debugging enabled. > > I'm afraid this is wrong. Those paths are used in the block layer issue > path. Most of the time this path does have user context. However, it's > legal to call it from tasklet context, and most error retries do this. > In that case, your GFP_KERNEL will have problems, so these have to be > GFP_ATOMIC, I'm afraid. In what path? I couldn't find one while reading the code. But I don't claim to understand it completely so I might have missed something. -Andi