Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755263Ab0F1Ip7 (ORCPT ); Mon, 28 Jun 2010 04:45:59 -0400 Received: from sh.osrg.net ([192.16.179.4]:56699 "EHLO sh.osrg.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754114Ab0F1Ip6 (ORCPT ); Mon, 28 Jun 2010 04:45:58 -0400 Date: Mon, 28 Jun 2010 17:45:21 +0900 To: axboe@kernel.dk Cc: fujita.tomonori@lab.ntt.co.jp, hch@lst.de, snitzer@redhat.com, dm-devel@redhat.com, James.Bottomley@suse.de, linux-kernel@vger.kernel.org, martin.petersen@oracle.com, akpm@linux-foundation.org, linux-scsi@vger.kernel.org Subject: Re: [PATCH 1/2] block: fix leaks associated with discard request payload From: FUJITA Tomonori In-Reply-To: <4C285AE8.9090702@kernel.dk> References: <20100628075738.GA26606@lst.de> <20100628171218Q.fujita.tomonori@lab.ntt.co.jp> <4C285AE8.9090702@kernel.dk> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-Id: <20100628174304S.fujita.tomonori@lab.ntt.co.jp> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-3.0 (sh.osrg.net [192.16.179.4]); Mon, 28 Jun 2010 17:45:24 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1779 Lines: 37 On Mon, 28 Jun 2010 10:18:48 +0200 Jens Axboe wrote: > On 2010-06-28 10:14, FUJITA Tomonori wrote: > > On Mon, 28 Jun 2010 09:57:38 +0200 > > Christoph Hellwig wrote: > > > >> On Sun, Jun 27, 2010 at 09:32:07PM +0900, FUJITA Tomonori wrote: > >>> On Sun, 27 Jun 2010 13:07:12 +0200 > >>> Christoph Hellwig wrote: > >>> > >>>>> How about this? > >>>> > >>>> As I tried to explain before this utterly confuses the I/O completion > >>>> path. With the patch applied even a simple mkfs.xfs that issues discard > >>>> just hangs. > >>> > >>> Wired. I just tried mkfs.xfs against scsi_debug with my block patches > >>> (I saw one discard command). Seemed that it worked fine. > >> > >> I've tracked it down to the call to scsi_requeue_command in scsi_end_request. > >> When the command is marked BLOCK_PC we'll just get it back as such in > >> ->prep_fn next time, but now it's reverting to the previous state. > > > > If scsi_end_request() calls scsi_requeue_command(), the command has a > > left over (i.e. hasn't finished all the data), right? You hit such > > condition with discard commands? > > > > BLOCK_PC requests don't hit this case since blk_end_request() always > > return false for PC. > > You can get requeues on the ->queuecommand() path as well, for a > variety of reasons, and that would be what Christoph is hitting. Probably, that's would be fine (we need to fix memory leak in that path). I guess that requeue with the partial completion commands might cause problems. -- 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/