From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:40895 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751776AbbJRAdU (ORCPT ); Sat, 17 Oct 2015 20:33:20 -0400 Subject: Patch "dm: fix AB-BA deadlock in __dm_destroy()" has been added to the 4.2-stable tree To: j-nomura@ce.jp.nec.com Cc: , From: Date: Sat, 17 Oct 2015 17:33:19 -0700 Message-ID: <1445128399106241@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled dm: fix AB-BA deadlock in __dm_destroy() to the 4.2-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: dm-fix-ab-ba-deadlock-in-__dm_destroy.patch and it can be found in the queue-4.2 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From 2a708cff93f1845b9239bc7d6310aef54e716c6a Mon Sep 17 00:00:00 2001 From: Junichi Nomura Date: Thu, 1 Oct 2015 08:31:51 +0000 Subject: dm: fix AB-BA deadlock in __dm_destroy() From: Junichi Nomura commit 2a708cff93f1845b9239bc7d6310aef54e716c6a upstream. __dm_destroy() takes io_barrier SRCU lock (dm_get_live_table) and suspend_lock in reverse order. Doing so can cause AB-BA deadlock: __dm_destroy dm_swap_table --------------------------------------------------- mutex_lock(suspend_lock) dm_get_live_table() srcu_read_lock(io_barrier) dm_sync_table() synchronize_srcu(io_barrier) .. waiting for dm_put_live_table() mutex_lock(suspend_lock) .. waiting for suspend_lock Fix this by taking the locks in proper order. Signed-off-by: Jun'ichi Nomura Fixes: ab7c7bb6f4ab ("dm: hold suspend_lock while suspending device during device deletion") Acked-by: Mikulas Patocka Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman --- drivers/md/dm.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -2952,8 +2952,6 @@ static void __dm_destroy(struct mapped_d might_sleep(); - map = dm_get_live_table(md, &srcu_idx); - spin_lock(&_minor_lock); idr_replace(&_minor_idr, MINOR_ALLOCED, MINOR(disk_devt(dm_disk(md)))); set_bit(DMF_FREEING, &md->flags); @@ -2967,14 +2965,14 @@ static void __dm_destroy(struct mapped_d * do not race with internal suspend. */ mutex_lock(&md->suspend_lock); + map = dm_get_live_table(md, &srcu_idx); if (!dm_suspended_md(md)) { dm_table_presuspend_targets(map); dm_table_postsuspend_targets(map); } - mutex_unlock(&md->suspend_lock); - /* dm_put_live_table must be before msleep, otherwise deadlock is possible */ dm_put_live_table(md, srcu_idx); + mutex_unlock(&md->suspend_lock); /* * Rare, but there may be I/O requests still going to complete, Patches currently in stable-queue which might be from j-nomura@ce.jp.nec.com are queue-4.2/dm-fix-ab-ba-deadlock-in-__dm_destroy.patch