From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f66.google.com ([74.125.82.66]:33219 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753076AbeGCVjl (ORCPT ); Tue, 3 Jul 2018 17:39:41 -0400 Received: by mail-wm0-f66.google.com with SMTP id z6-v6so11471750wma.0 for ; Tue, 03 Jul 2018 14:39:40 -0700 (PDT) Date: Tue, 3 Jul 2018 23:39:32 +0200 From: Alexandru Moise <00moses.alexander00@gmail.com> To: Jens Axboe Cc: stable@vger.kernel.org, gregkh@linuxfoundation.org Subject: Re: [PATCH] block: don't use blocking queue entered for recursive bio submits Message-ID: <20180703213932.GA10884@gmail.com> References: <20180703211538.GA9088@gmail.com> <8e959bb2-5cd8-9a1d-bc48-1e32f2681ef4@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8e959bb2-5cd8-9a1d-bc48-1e32f2681ef4@kernel.dk> Sender: stable-owner@vger.kernel.org List-ID: On Tue, Jul 03, 2018 at 03:20:31PM -0600, Jens Axboe wrote: > On 7/3/18 3:15 PM, Jens Axboe wrote: > > commit cd4a4ae4683dc2e09380118e205e057896dcda2b upstream. > > > > If we end up splitting a bio and the queue goes away between > > the initial submission and the later split submission, then we > > can block forever in blk_queue_enter() waiting for the reference > > to drop to zero. This will never happen, since we already hold > > a reference. > > > > Mark a split bio as already having entered the queue, so we can > > just use the live non-blocking queue enter variant. > > > > Thanks to Tetsuo Handa for the analysis. > > > > We're running fio tests and the tasks get stuck in a D state forever > > when systemd-udevd tries to read the partition table. This patch solves > > it. Please apply to 4.17 stable. > > > > Reported-by: syzbot+c4f9cebf9d651f6e54de@syzkaller.appspotmail.com > > Signed-off-by: Jens Axboe > > Signed-off-by: Alexandru Moise <00moses.alexander00@gmail.com> > > WTF? Please don't send out emails with my name. Ever. > Crap, that's the last thing I intended. I need to set fire to my scripts now, along with my lazy eye. Please accept my most sincere apologies for this stupid mistake. ../Alex > -- > Jens Axboe >