From patchwork Wed Sep 12 16:11:19 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vitaly Kuznetsov X-Patchwork-Id: 10597999 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D62CF921 for ; Wed, 12 Sep 2018 16:11:23 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C59AD2A720 for ; Wed, 12 Sep 2018 16:11:23 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B72F02A728; Wed, 12 Sep 2018 16:11:23 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 597242A73B for ; Wed, 12 Sep 2018 16:11:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727709AbeILVQf (ORCPT ); Wed, 12 Sep 2018 17:16:35 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:45536 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726672AbeILVQe (ORCPT ); Wed, 12 Sep 2018 17:16:34 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9A0DE804B4DB; Wed, 12 Sep 2018 16:11:21 +0000 (UTC) Received: from vitty.brq.redhat.com (unknown [10.43.2.155]) by smtp.corp.redhat.com (Postfix) with ESMTP id 61E72112C243; Wed, 12 Sep 2018 16:11:20 +0000 (UTC) From: Vitaly Kuznetsov To: linux-kernel@vger.kernel.org Cc: linux-pm@vger.kernel.org, "Rafael J. Wysocki" , Andrew Morton , Dmitry Vyukov , "Paul E. McKenney" Subject: [PATCH RFC] kernel/hung_task.c: disable on suspend Date: Wed, 12 Sep 2018 18:11:19 +0200 Message-Id: <20180912161119.2692-1-vkuznets@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.8]); Wed, 12 Sep 2018 16:11:21 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.8]); Wed, 12 Sep 2018 16:11:21 +0000 (UTC) for IP:'10.11.54.3' DOMAIN:'int-mx03.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'vkuznets@redhat.com' RCPT:'' Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP It is possible to observe hung_task complaints when system goes to suspend-to-idle state: PM: Syncing filesystems ... done. Freezing user space processes ... (elapsed 0.001 seconds) done. OOM killer disabled. Freezing remaining freezable tasks ... (elapsed 0.002 seconds) done. sd 0:0:0:0: [sda] Synchronizing SCSI cache INFO: task bash:1569 blocked for more than 120 seconds. Not tainted 4.19.0-rc3_+ #687 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. bash D 0 1569 604 0x00000000 Call Trace: ? __schedule+0x1fe/0x7e0 schedule+0x28/0x80 suspend_devices_and_enter+0x4ac/0x750 pm_suspend+0x2c0/0x310 Register a PM notifier to disable the detector on suspend and re-enable back on wakeup. Signed-off-by: Vitaly Kuznetsov --- RFC: It really makes me wonder why nobody reported this before, makes me think I'm missing something. --- kernel/hung_task.c | 26 +++++++++++++++++++++++++- 1 file changed, 25 insertions(+), 1 deletion(-) diff --git a/kernel/hung_task.c b/kernel/hung_task.c index b9132d1269ef..d75f288c016f 100644 --- a/kernel/hung_task.c +++ b/kernel/hung_task.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include #include @@ -242,6 +243,24 @@ void reset_hung_task_detector(void) } EXPORT_SYMBOL_GPL(reset_hung_task_detector); +static bool hung_detector_suspended; + +static int hungtask_pm_notify(struct notifier_block *self, + unsigned long action, void *hcpu) +{ + switch (action) { + case PM_SUSPEND_PREPARE: + hung_detector_suspended = true; + break; + case PM_POST_SUSPEND: + hung_detector_suspended = false; + break; + default: + break; + } + return NOTIFY_OK; +} + /* * kthread which checks for tasks stuck in D state */ @@ -261,7 +280,8 @@ static int watchdog(void *dummy) interval = min_t(unsigned long, interval, timeout); t = hung_timeout_jiffies(hung_last_checked, interval); if (t <= 0) { - if (!atomic_xchg(&reset_hung_task, 0)) + if (!atomic_xchg(&reset_hung_task, 0) && + !hung_detector_suspended) check_hung_uninterruptible_tasks(timeout); hung_last_checked = jiffies; continue; @@ -275,6 +295,10 @@ static int watchdog(void *dummy) static int __init hung_task_init(void) { atomic_notifier_chain_register(&panic_notifier_list, &panic_block); + + /* Disable hung task detector on suspend */ + pm_notifier(hungtask_pm_notify, 0); + watchdog_task = kthread_run(watchdog, NULL, "khungtaskd"); return 0;