Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965113Ab3CZPxJ (ORCPT ); Tue, 26 Mar 2013 11:53:09 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:53784 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965040Ab3CZPWh (ORCPT ); Tue, 26 Mar 2013 11:22:37 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Guo Chao , Alexander Viro , "M. Hindess" , Nikanth Karthikesan , Jens Axboe , Andrew Morton , Luis Henriques Subject: [PATCH 025/150] loopdev: fix a deadlock Date: Tue, 26 Mar 2013 15:18:44 +0000 Message-Id: <1364311249-14454-26-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1364311249-14454-1-git-send-email-luis.henriques@canonical.com> References: <1364311249-14454-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2197 Lines: 70 3.5.7.9 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Guo Chao commit 5370019dc2d2c2ff90e95d181468071362934f3a upstream. bd_mutex and lo_ctl_mutex can be held in different order. Path #1: blkdev_open blkdev_get __blkdev_get (hold bd_mutex) lo_open (hold lo_ctl_mutex) Path #2: blkdev_ioctl lo_ioctl (hold lo_ctl_mutex) lo_set_capacity (hold bd_mutex) Lockdep does not report it, because path #2 actually holds a subclass of lo_ctl_mutex. This subclass seems creep into the code by mistake. The patch author actually just mentioned it in the changelog, see commit f028f3b2 ("loop: fix circular locking in loop_clr_fd()"), also see: http://marc.info/?l=linux-kernel&m=123806169129727&w=2 Path #2 hold bd_mutex to call bd_set_size(), I've protected it with i_mutex in a previous patch, so drop bd_mutex at this site. Signed-off-by: Guo Chao Cc: Alexander Viro Cc: Guo Chao Cc: M. Hindess Cc: Nikanth Karthikesan Cc: Jens Axboe Signed-off-by: Andrew Morton Signed-off-by: Jens Axboe Signed-off-by: Luis Henriques --- drivers/block/loop.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 3bba655..11e702c 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1263,11 +1263,9 @@ static int loop_set_capacity(struct loop_device *lo, struct block_device *bdev) /* the width of sector_t may be narrow for bit-shift */ sz = sec; sz <<= 9; - mutex_lock(&bdev->bd_mutex); bd_set_size(bdev, sz); /* let user-space know about the new size */ kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE); - mutex_unlock(&bdev->bd_mutex); out: return err; -- 1.8.1.2 -- 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/