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Jones" To: Ming Lei Cc: Damien Le Moal , Jens Axboe , linux-block@vger.kernel.org, Jeff Moyer , Jiri Jaburek , Christoph Hellwig , Bart Van Assche , Hannes Reinecke , Chaitanya Kulkarni Subject: Re: [PATCH] block: elevator: avoid to load iosched module from this disk Message-ID: <20240907111453.GA1450@redhat.com> References: <20240907014331.176152-1-ming.lei@redhat.com> <20240907073522.GW1450@redhat.com> <4d7280eb-7f26-4652-a1d4-4f82c4d99a4c@kernel.org> <20240907100213.GY1450@redhat.com> <20240907103632.GZ1450@redhat.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 On Sat, Sep 07, 2024 at 07:02:30PM +0800, Ming Lei wrote: > BTW, the issue can be reproduced 100% by: > > echo "deadlock" > /sys/block/$ROOT_DISK/queue/scheduler That doesn't reproduce it for me (reliably). Although I'm not surprised as this bug has been _very_ tricky to reproduce! Sometimes I think I have a definite reproducer, only for it to go away when some tiny detail changes. > > This seems like the neatest (or shortest) fix so far, but doesn't it > > "mix up layers" by checking elv_iosched_store? > > It is just one exception for 'scheduler' sysfs attribute wrt. freezing > queue for storing, and the check can be done via the attribute > name("scheduler") too. Fair enough. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-builder quickly builds VMs from scratch http://libguestfs.org/virt-builder.1.html