Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934889AbcJTIvI (ORCPT ); Thu, 20 Oct 2016 04:51:08 -0400 Received: from mx2.suse.de ([195.135.220.15]:47028 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753639AbcJTIvE (ORCPT ); Thu, 20 Oct 2016 04:51:04 -0400 From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Junichi Nomura , Mike Snitzer , Jiri Slaby Subject: [PATCH 3.12 1/5] dm: fix AB-BA deadlock in __dm_destroy() Date: Thu, 20 Oct 2016 10:51:00 +0200 Message-Id: <52342f2c308ee92f3e9516c4c2ceb5937bc881e7.1476953405.git.jslaby@suse.cz> X-Mailer: git-send-email 2.10.1 In-Reply-To: <8e335ed458e79a74833fb846a5607c814c762bf8.1476953088.git.jslaby@suse.cz> References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2243 Lines: 64 From: Junichi Nomura 3.12-stable review patch. If anyone has any objections, please let me know. =============== 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: Jiri Slaby --- drivers/md/dm.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 5a0b1742f794..78ab0a131cf1 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -2434,7 +2434,6 @@ static void __dm_destroy(struct mapped_device *md, bool wait) might_sleep(); spin_lock(&_minor_lock); - map = dm_get_live_table(md, &srcu_idx); idr_replace(&_minor_idr, MINOR_ALLOCED, MINOR(disk_devt(dm_disk(md)))); set_bit(DMF_FREEING, &md->flags); spin_unlock(&_minor_lock); @@ -2444,14 +2443,14 @@ static void __dm_destroy(struct mapped_device *md, bool wait) * 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, -- 2.10.1