From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-Path: Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 11.2 \(3445.5.20\)) Subject: Re: [PATCH BUGFIX 1/1] block, bfq: add requeue-request hook From: Paolo Valente In-Reply-To: <1517903761.9843.12.camel@gmx.de> Date: Tue, 6 Feb 2018 10:38:03 +0100 Cc: Oleksandr Natalenko , Jens Axboe , linux-block , Linux Kernel Mailing List , Ulf Hansson , Mark Brown , Linus Walleij , 'Paolo Valente' via bfq-iosched , Alban Browaeys , ming.lei@redhat.com, ivan@ludios.org, 169364@studenti.unimore.it, Serena Ziviani Message-Id: <899B68CC-5955-4418-8BFF-DC55A743A61B@linaro.org> References: <20180205190510.5499-1-paolo.valente@linaro.org> <20180205190510.5499-2-paolo.valente@linaro.org> <1517903761.9843.12.camel@gmx.de> To: Mike Galbraith List-ID: > Il giorno 06 feb 2018, alle ore 08:56, Mike Galbraith = ha scritto: >=20 > On Tue, 2018-02-06 at 08:44 +0100, Oleksandr Natalenko wrote: >> Hi, Paolo. >>=20 >> I can confirm that this patch fixes cfdisk hang for me. I've also = tried=20 >> to trigger the issue Mike has encountered, but with no luck (maybe, I=20= >> wasn't insistent enough, just was doing dd on usb-storage device in = the=20 >> VM). >=20 > I was doing kbuilds, and it blew up on me twice. Switching back to = cfq > seemed to confirm it was indeed the patch causing trouble, but that's > by no means a certainty. >=20 Hi Mike, as you can imagine, I didn't get any failure in my pre-submission tests on this patch. In addition, it is not that easy to link this patch, which just adds some internal bfq housekeeping in case of a requeue, with a corruption of external lists for general I/O management. In this respect, as Oleksandr comments point out, by switching from cfq to bfq, you switch between much more than two schedulers. Anyway, who knows ... Maybe this report will ring a bell with some block-layer expert, or, hopefully, next feedback will help puzzle this out. Thanks, Paolo > -Mike From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752401AbeBFJia (ORCPT ); Tue, 6 Feb 2018 04:38:30 -0500 Received: from mail-wm0-f46.google.com ([74.125.82.46]:53226 "EHLO mail-wm0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752263AbeBFJiH (ORCPT ); Tue, 6 Feb 2018 04:38:07 -0500 X-Google-Smtp-Source: AH8x2246vkHCo1LTcXUsIQTiaUIOkXE17QW+T7hTT7H48yAal76OxFYLXLWkFxaIiqlTOkduTsUu+A== Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 11.2 \(3445.5.20\)) Subject: Re: [PATCH BUGFIX 1/1] block, bfq: add requeue-request hook From: Paolo Valente In-Reply-To: <1517903761.9843.12.camel@gmx.de> Date: Tue, 6 Feb 2018 10:38:03 +0100 Cc: Oleksandr Natalenko , Jens Axboe , linux-block , Linux Kernel Mailing List , Ulf Hansson , Mark Brown , Linus Walleij , "'Paolo Valente' via bfq-iosched" , Alban Browaeys , ming.lei@redhat.com, ivan@ludios.org, 169364@studenti.unimore.it, Serena Ziviani Message-Id: <899B68CC-5955-4418-8BFF-DC55A743A61B@linaro.org> References: <20180205190510.5499-1-paolo.valente@linaro.org> <20180205190510.5499-2-paolo.valente@linaro.org> <1517903761.9843.12.camel@gmx.de> To: Mike Galbraith X-Mailer: Apple Mail (2.3445.5.20) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id w169cYXQ021384 > Il giorno 06 feb 2018, alle ore 08:56, Mike Galbraith ha scritto: > > On Tue, 2018-02-06 at 08:44 +0100, Oleksandr Natalenko wrote: >> Hi, Paolo. >> >> I can confirm that this patch fixes cfdisk hang for me. I've also tried >> to trigger the issue Mike has encountered, but with no luck (maybe, I >> wasn't insistent enough, just was doing dd on usb-storage device in the >> VM). > > I was doing kbuilds, and it blew up on me twice. Switching back to cfq > seemed to confirm it was indeed the patch causing trouble, but that's > by no means a certainty. > Hi Mike, as you can imagine, I didn't get any failure in my pre-submission tests on this patch. In addition, it is not that easy to link this patch, which just adds some internal bfq housekeeping in case of a requeue, with a corruption of external lists for general I/O management. In this respect, as Oleksandr comments point out, by switching from cfq to bfq, you switch between much more than two schedulers. Anyway, who knows ... Maybe this report will ring a bell with some block-layer expert, or, hopefully, next feedback will help puzzle this out. Thanks, Paolo > -Mike