From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:38176 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751143AbdLARaO (ORCPT ); Fri, 1 Dec 2017 12:30:14 -0500 Date: Sat, 2 Dec 2017 01:29:59 +0800 From: Ming Lei To: Alban Browaeys Cc: Jens Axboe , linux-block@vger.kernel.org Subject: Re: blk-mq + bfq: udevd hang on usb2 storages Message-ID: <20171201172958.GA22528@ming.t460p> References: <1512147869.8698.21.camel@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1512147869.8698.21.camel@gmail.com> Sender: linux-block-owner@vger.kernel.org List-Id: linux-block@vger.kernel.org On Fri, Dec 01, 2017 at 06:04:29PM +0100, Alban Browaeys wrote: > I initially reported as https://bugzilla.kernel.org/show_bug.cgi?id=198 > 023 . > > I have now bisected this issue to commit a6a252e6491443c1c1 "blk-mq- > sched: decide how to handle flush rq via RQF_FLUSH_SEQ". > > This is with an USB stick Sandisk Cruzer (USB Version: 2.10) I > regressed with. > systemctl restart systemd-udevd restores sanity. >>From my investigation, looks the issue is in BFQ: https://marc.info/?l=linux-block&m=151214241518562&w=2 Could you apply the attached debug patch, run your test and provide us the log? Thanks, Ming