Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933424Ab3HGV0u (ORCPT ); Wed, 7 Aug 2013 17:26:50 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:40123 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933289Ab3HGV0s (ORCPT ); Wed, 7 Aug 2013 17:26:48 -0400 Date: Wed, 7 Aug 2013 14:26:47 -0700 From: Andrew Morton To: Ed Cashin Cc: Subject: Re: [PATCH] aoe: adjust ref of head for compound page tails Message-Id: <20130807142647.6614d3ec88a7af12cba4505a@linux-foundation.org> In-Reply-To: References: <0c8aff39249c1da6b9cc3356650149d065c3ebd2.1375320764.git.ecashin@coraid.com> <20130807140021.57a40fb31807f16b525f6ff3@linux-foundation.org> X-Mailer: Sylpheed 3.2.0beta5 (GTK+ 2.24.10; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1325 Lines: 29 On Wed, 7 Aug 2013 17:21:32 -0400 Ed Cashin wrote: > > What are the end-user-visible effects of the problem which is being > > fixed? Please always include this info when fixing bugs so that others > > can work out what kernel version(s) need the patch. > > > Sorry. I tried to cover that but maybe should have separated it more clearly from the running text. > > The patch changes the current behavior encountered with direct I/O and aoe: > > aoe can BUG when direct I/O used > > ... to a new behavior: > > aoe does not BUG when direct I/O is used > > And the user will never know that instead aoe is manipulating the _count of the head page, even though that's what's happening with this patch applied. > > (The user-visible effects that motivated the older patch that added the BUG to aoe when page tails are used for block I/O was a VM_BUG_ON that occurred when the aoe driver manipulated the _count of a compound page tail.) OK, I added "Fix a BUG which can trigger when direct-IO is used with AOE". Which kernel versions are affected? -- 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/