From patchwork Fri Nov 13 21:48:10 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kamal Mostafa X-Patchwork-Id: 544474 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id CE67A141426; Sat, 14 Nov 2015 08:48:24 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1ZxMCk-0002nu-FD; Fri, 13 Nov 2015 21:48:22 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1ZxMCc-0002iY-0n for kernel-team@lists.ubuntu.com; Fri, 13 Nov 2015 21:48:14 +0000 Received: from 1.general.kamal.us.vpn ([10.172.68.52] helo=fourier) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.76) (envelope-from ) id 1ZxMCb-0007Ve-5A; Fri, 13 Nov 2015 21:48:13 +0000 Received: from kamal by fourier with local (Exim 4.82) (envelope-from ) id 1ZxMCY-0003Qe-Ue; Fri, 13 Nov 2015 13:48:10 -0800 From: Kamal Mostafa To: Junichi Nomura Subject: [3.13.y-ckt stable] Patch "dm: fix AB-BA deadlock in __dm_destroy()" has been added to staging queue Date: Fri, 13 Nov 2015 13:48:10 -0800 Message-Id: <1447451290-13150-1-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 X-Extended-Stable: 3.13 Cc: Kamal Mostafa , Mikulas Patocka , kernel-team@lists.ubuntu.com, Mike Snitzer X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com This is a note to let you know that I have just added a patch titled dm: fix AB-BA deadlock in __dm_destroy() to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.13.y-queue This patch is scheduled to be released in version 3.13.11-ckt30. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.13.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From a1e5fc6837dea12692cc4437a03b4bc01cfc775d 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() 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: Kamal Mostafa --- drivers/md/dm.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) -- 1.9.1 diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 5489410..071b9ad 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -2490,14 +2490,14 @@ 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,