From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933417Ab1BPA6m (ORCPT ); Tue, 15 Feb 2011 19:58:42 -0500 Received: from kroah.org ([198.145.64.141]:46129 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933337Ab1BPAvV (ORCPT ); Tue, 15 Feb 2011 19:51:21 -0500 X-Mailbox-Line: From gregkh@clark.kroah.org Tue Feb 15 16:21:13 2011 Message-Id: <20110216002113.429526641@clark.kroah.org> User-Agent: quilt/0.48-11.2 Date: Tue, 15 Feb 2011 16:21:52 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Chris Mason , NeilBrown Subject: [patch 144/176] md_make_request: dont touch the bio after calling make_request In-Reply-To: <20110216002212.GA9246@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.36-stable review patch. If anyone has any objections, please let us know. ------------------ From: Chris Mason commit e91ece5590b3c728624ab57043fc7a05069c604a upstream. md_make_request was calling bio_sectors() for part_stat_add after it was calling the make_request function. This is bad because the make_request function can free the bio and because the bi_size field can change around. The fix here was suggested by Jens Axboe. It saves the sector count before the make_request call. I hit this with CONFIG_DEBUG_PAGEALLOC turned on while trying to break his pretty fusionio card. Signed-off-by: Chris Mason Signed-off-by: NeilBrown Signed-off-by: Greg Kroah-Hartman --- drivers/md/md.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -220,6 +220,7 @@ static int md_make_request(struct reques mddev_t *mddev = q->queuedata; int rv; int cpu; + unsigned int sectors; if (mddev == NULL || mddev->pers == NULL || !mddev->ready) { @@ -244,12 +245,16 @@ static int md_make_request(struct reques atomic_inc(&mddev->active_io); rcu_read_unlock(); + /* + * save the sectors now since our bio can + * go away inside make_request + */ + sectors = bio_sectors(bio); rv = mddev->pers->make_request(mddev, bio); cpu = part_stat_lock(); part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]); - part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw], - bio_sectors(bio)); + part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw], sectors); part_stat_unlock(); if (atomic_dec_and_test(&mddev->active_io) && mddev->suspended)