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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 28E2CC17447 for ; Wed, 13 Nov 2019 14:25:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 018F1222C9 for ; Wed, 13 Nov 2019 14:25:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=natalenko.name header.i=@natalenko.name header.b="sxga0JhF" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727643AbfKMOZR (ORCPT ); Wed, 13 Nov 2019 09:25:17 -0500 Received: from vulcan.natalenko.name ([104.207.131.136]:51196 "EHLO vulcan.natalenko.name" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726410AbfKMOZR (ORCPT ); Wed, 13 Nov 2019 09:25:17 -0500 Received: from mail.natalenko.name (vulcan.natalenko.name [IPv6:fe80::5400:ff:fe0c:dfa0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by vulcan.natalenko.name (Postfix) with ESMTPSA id B3925628D29; Wed, 13 Nov 2019 15:25:14 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=natalenko.name; s=dkim-20170712; t=1573655114; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=sFOnhcG2h9p6Leq82h9jLugL5gyFvgzjK5JNz6So8WM=; b=sxga0JhFMHZHIuZ6n5ejkVM3p0+cai1t1ON/G4fONpk2HwNcJ9AzXwlClxF48s9Y4Is+2N SkaWXY4Z4QBmto6aheOP5bAgXeVkdb8mvRob2Jaq/n8kR9j2pDLz5kNeuXApOGN9tni4AM 22m7I/YCfNmodXWId2JM9bXsLz5YUYk= MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Wed, 13 Nov 2019 15:25:14 +0100 From: Oleksandr Natalenko To: Paolo Valente Cc: Jens Axboe , linux-block , linux-kernel@vger.kernel.org, ulf.hansson@linaro.org, linus.walleij@linaro.org, bfq-iosched@googlegroups.com, Chris Evich , Patrick Dung , Thorsten Schubert Subject: Re: [PATCH BUGFIX] block, bfq: deschedule empty bfq_queues not referred by any process In-Reply-To: <2FB3736A-693E-44B9-9D1F-39AE0D016644@linaro.org> References: <20191112074856.40433-1-paolo.valente@linaro.org> <2FB3736A-693E-44B9-9D1F-39AE0D016644@linaro.org> User-Agent: Roundcube Webmail/1.4.0 Message-ID: <65fc0bffbcb2296d121b3d5a79108e76@natalenko.name> X-Sender: oleksandr@natalenko.name Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 13.11.2019 14:52, Paolo Valente wrote: >> I'm not sure if I see things right, but this commit along with v5.3.11 >> kernel causes almost all boots to hang (for instance, on mounting the >> FS). Once the scheduler is changed to something else than BFQ (I set >> the I/O scheduler early via udev rule), multiple reboots go just fine. >> > > If you switch back to bfq after the boot, can you still reproduce the > hang? I didn't try to switch schedulers, but what I see now is once the system is able to boot with BFQ, the I/O can still hang on I/O burst (which for me happens to happen during VM reboot). This may also not hang forever, but just slow down considerably. I've noticed this inside a KVM VM, not on a real HW. >> Is this commit also applicable to 5.3 kernels? > > It is. OK, thanks for clarification. -- Oleksandr Natalenko (post-factum)