Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757571Ab3HGX1p (ORCPT ); Wed, 7 Aug 2013 19:27:45 -0400 Received: from server506h.appriver.com ([50.56.144.38]:58825 "EHLO server506.appriver.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752651Ab3HGX1n convert rfc822-to-8bit (ORCPT ); Wed, 7 Aug 2013 19:27:43 -0400 X-Note-AR-ScanTimeLocal: 8/7/2013 6:27:42 PM X-Policy: GLOBAL - coraid.com X-Policy: GLOBAL - coraid.com X-Primary: ecashin@coraid.com X-Note: This Email was scanned by AppRiver SecureTide X-Virus-Scan: V- X-Note-SnifferID: 0 X-Note: TCH-CT/SI:0-34/SG:2 8/7/2013 6:27:40 PM X-GBUdb-Analysis: 0, 10.242.229.139, Ugly c=1 p=-0.977973 Source White X-Signature-Violations: 0-0-0-3945-c X-Note-419: 0 ms. Fail:0 Chk:1343 of 1343 total X-Note: SCH-CT/SI:0-1343/SG:1 8/7/2013 6:27:28 PM X-Note: Spam Tests Failed: X-Country-Path: PRIVATE->PRIVATE->UNITED STATES X-Note-Sending-IP: 10.242.229.139 X-Note-Reverse-DNS: X-Note-Return-Path: ecashin@coraid.com X-Note: User Rule Hits: X-Note: Global Rule Hits: G319 G320 G321 G322 G326 G327 G434 X-Note: Encrypt Rule Hits: X-Note: Mail Class: VALID X-Note: Headers Injected Subject: Re: [PATCH] aoe: adjust ref of head for compound page tails MIME-Version: 1.0 (Apple Message framework v1085) Content-Type: text/plain; charset="us-ascii" From: Ed Cashin In-Reply-To: <20130807142647.6614d3ec88a7af12cba4505a@linux-foundation.org> Date: Wed, 7 Aug 2013 19:27:40 -0400 CC: Content-Transfer-Encoding: 8BIT Message-ID: <782613DB-4C38-450C-BBC2-E14FA64D44AC@coraid.com> References: <0c8aff39249c1da6b9cc3356650149d065c3ebd2.1375320764.git.ecashin@coraid.com> <20130807140021.57a40fb31807f16b525f6ff3@linux-foundation.org> <20130807142647.6614d3ec88a7af12cba4505a@linux-foundation.org> To: Andrew Morton X-Mailer: Apple Mail (2.1085) X-Rerouted-By-Exchange: X-Rerouted-By-Exchange: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1559 Lines: 38 On Aug 7, 2013, at 5:26 PM, Andrew Morton wrote: > On Wed, 7 Aug 2013 17:21:32 -0400 Ed Cashin wrote: ... >> 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? That BUG was added to the aoe driver in a commit that first appears in v3.7. It persists until this patch adds the code that handles the situation that the BUG was intended to detect. [ecashin@marino linux]$ git describe --contains --match 'v*' 69cf2d85de773d998798e47e3335b85e5645d157 v3.7-rc1~110^2~22 [ecashin@marino linux]$ -- Ed Cashin ecashin@coraid.com -- 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/