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=-7.0 required=3.0 tests=INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 ABB99ECDE32 for ; Wed, 17 Oct 2018 07:33:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 695302151D for ; Wed, 17 Oct 2018 07:33:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 695302151D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.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 S1727086AbeJQP1W (ORCPT ); Wed, 17 Oct 2018 11:27:22 -0400 Received: from mail-ot1-f68.google.com ([209.85.210.68]:40673 "EHLO mail-ot1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726622AbeJQP1V (ORCPT ); Wed, 17 Oct 2018 11:27:21 -0400 Received: by mail-ot1-f68.google.com with SMTP id w67so25193942ota.7; Wed, 17 Oct 2018 00:33:00 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=jqmsMVNo0twCcj0fFEXS/qA3tiQNjli7UOaEwVtH0Y0=; b=MRYRz9ghXlx2y1L/SVJvvCV14+VvvNZx3h+D/eszTC0f3PfMjq2um4q/Z6yqle8AtO VY+s8b124+IjCqOSdZyPdwdQ9deKVtrMrnWA3GcnBoHQO0L+18h8h0ZNzS/MkMAxaHD7 OMQK8DZXwEG10GXoqLd592Rg2ZDeLtWblBBZlNNXBYTuBlvJI3lidmuteRX2ZnqAThNE CyRfq5xVtU/e0WSKc927K4AuKzVgnexShmjz3XP3kem4WWna5NjwxllJgKH9hl5/wFcS YlOjTDUQ0f4oVcnij8R5oJfkrlJUfxin5iHv2rC3mQNxsz8+8SRcezFMdwx5d5geieqv FpFA== X-Gm-Message-State: ABuFfogujUbKv1OQgWcYa234MTQnNxooYFJ2OulXsLPLg/wFeZ1X85EX WLesXmvURLx7G+p4dW79xEZw8+kRdEGxQwhJ8SA= X-Google-Smtp-Source: ACcGV61siK7CFNkZZS9yYbNdL5mGuBGcOhhoDIzBsrwWDIuv0Q5KqFLfcROo7dLvlpzep01mlLvJaTgHOX/j+wowJic= X-Received: by 2002:a9d:5549:: with SMTP id h9mr3216711oti.244.1539761579845; Wed, 17 Oct 2018 00:32:59 -0700 (PDT) MIME-Version: 1.0 References: <20181016165513.7133-1-vkuznets@redhat.com> In-Reply-To: <20181016165513.7133-1-vkuznets@redhat.com> From: "Rafael J. Wysocki" Date: Wed, 17 Oct 2018 09:32:48 +0200 Message-ID: Subject: Re: [PATCH v3] kernel/hung_task.c: disable on suspend To: Vitaly Kuznetsov Cc: Linux Kernel Mailing List , Linux PM , "Rafael J. Wysocki" , Andrew Morton , Dmitry Vyukov , Paul McKenney , Oleg Nesterov Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 16, 2018 at 6:55 PM Vitaly Kuznetsov wrote: > > It is possible to observe hung_task complaints when system goes to > suspend-to-idle state: > > # echo freeze > /sys/power/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 > --- > Changes since v2: > - Resurrect 'v1' as zeroing timeouts can be racy [Rafael J. Wysocki] > --- > kernel/hung_task.c | 28 +++++++++++++++++++++++++++- > 1 file changed, 27 insertions(+), 1 deletion(-) > > diff --git a/kernel/hung_task.c b/kernel/hung_task.c > index b9132d1269ef..41955c5d8427 100644 > --- a/kernel/hung_task.c > +++ b/kernel/hung_task.c > @@ -15,6 +15,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -242,6 +243,26 @@ 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: > + case PM_HIBERNATION_PREPARE: Please add PM_RESTORE_PREPARE here -> > + hung_detector_suspended = true; > + break; > + case PM_POST_SUSPEND: > + case PM_POST_HIBERNATION: -> and PM_POST_RESTORE here for completeness. > + hung_detector_suspended = false; > + break; > + default: > + break; > + } > + return NOTIFY_OK; > +} > + > /* > * kthread which checks for tasks stuck in D state > */ > @@ -261,7 +282,8 @@ 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 +297,10 @@ 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; > -- Apart from the above it is fine by me. This is the minimum fix for the issue at hand AFAICS. Thanks, Rafael