From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5DFBFC07520 for ; Thu, 13 Sep 2018 13:37:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1CF7020854 for ; Thu, 13 Sep 2018 13:37:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1CF7020854 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729340AbeIMSrB (ORCPT ); Thu, 13 Sep 2018 14:47:01 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:59542 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728432AbeIMSrB (ORCPT ); Thu, 13 Sep 2018 14:47:01 -0400 Received: from localhost (ip-213-127-77-73.ip.prioritytelecom.net [213.127.77.73]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 0C1E5D10; Thu, 13 Sep 2018 13:37:29 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, John Pittman , Mike Snitzer , Sasha Levin Subject: [PATCH 4.9 45/78] dm kcopyd: avoid softlockup in run_complete_job Date: Thu, 13 Sep 2018 15:31:32 +0200 Message-Id: <20180913131810.365051343@linuxfoundation.org> X-Mailer: git-send-email 2.19.0 In-Reply-To: <20180913131805.732342940@linuxfoundation.org> References: <20180913131805.732342940@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: John Pittman [ Upstream commit 784c9a29e99eb40b842c29ecf1cc3a79e00fb629 ] It was reported that softlockups occur when using dm-snapshot ontop of slow (rbd) storage. E.g.: [ 4047.990647] watchdog: BUG: soft lockup - CPU#10 stuck for 22s! [kworker/10:23:26177] ... [ 4048.034151] Workqueue: kcopyd do_work [dm_mod] [ 4048.034156] RIP: 0010:copy_callback+0x41/0x160 [dm_snapshot] ... [ 4048.034190] Call Trace: [ 4048.034196] ? __chunk_is_tracked+0x70/0x70 [dm_snapshot] [ 4048.034200] run_complete_job+0x5f/0xb0 [dm_mod] [ 4048.034205] process_jobs+0x91/0x220 [dm_mod] [ 4048.034210] ? kcopyd_put_pages+0x40/0x40 [dm_mod] [ 4048.034214] do_work+0x46/0xa0 [dm_mod] [ 4048.034219] process_one_work+0x171/0x370 [ 4048.034221] worker_thread+0x1fc/0x3f0 [ 4048.034224] kthread+0xf8/0x130 [ 4048.034226] ? max_active_store+0x80/0x80 [ 4048.034227] ? kthread_bind+0x10/0x10 [ 4048.034231] ret_from_fork+0x35/0x40 [ 4048.034233] Kernel panic - not syncing: softlockup: hung tasks Fix this by calling cond_resched() after run_complete_job()'s callout to the dm_kcopyd_notify_fn (which is dm-snap.c:copy_callback in the above trace). Signed-off-by: John Pittman Signed-off-by: Mike Snitzer Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/md/dm-kcopyd.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/md/dm-kcopyd.c +++ b/drivers/md/dm-kcopyd.c @@ -454,6 +454,8 @@ static int run_complete_job(struct kcopy if (atomic_dec_and_test(&kc->nr_jobs)) wake_up(&kc->destroyq); + cond_resched(); + return 0; }