From: Tejun Heo <tj@kernel.org>
To: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org,
Dan Williams <dan.j.williams@intel.com>,
Omar Sandoval <osandov@osandov.com>,
Arthur Marsh <arthur.marsh@internode.on.net>,
linux-scsi@vger.kernel.org
Subject: Re: [PATCH 1/4] block: Allow bdi re-registration
Date: Thu, 9 Mar 2017 11:39:39 -0500 [thread overview]
Message-ID: <20170309163939.GA28982@htj.duckdns.org> (raw)
In-Reply-To: <20170309101624.25901-2-jack@suse.cz>
On Thu, Mar 09, 2017 at 11:16:21AM +0100, Jan Kara wrote:
> SCSI can call device_add_disk() several times for one request queue when
> a device in unbound and bound, creating new gendisk each time. This will
> lead to bdi being repeatedly registered and unregistered. This was not a
> big problem until commit 165a5e22fafb "block: Move bdi_unregister() to
> del_gendisk()" since bdi was only registered repeatedly (bdi_register()
> handles repeated calls fine, only we ended up leaking reference to
> gendisk due to overwriting bdi->owner) but unregistered only in
> blk_cleanup_queue() which didn't get called repeatedly. After
> 165a5e22fafb we were doing correct bdi_register() - bdi_unregister()
> cycles however bdi_unregister() is not prepared for it. So make sure
> bdi_unregister() cleans up bdi in such a way that it is prepared for
> a possible following bdi_register() call.
>
> An easy way to provoke this behavior is to enable
> CONFIG_DEBUG_TEST_DRIVER_REMOVE and use scsi_debug driver to create a
> scsi disk which immediately hangs without this fix.
>
> Fixes: 165a5e22fafb127ecb5914e12e8c32a1f0d3f820
> Tested-by: Omar Sandoval <osandov@fb.com>
> Signed-off-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Thanks!
--
tejun
next prev parent reply other threads:[~2017-03-09 16:39 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-09 10:16 [PATCH 0/4 v2] block: Fixes for bdi handling Jan Kara
2017-03-09 10:16 ` [PATCH 1/4] block: Allow bdi re-registration Jan Kara
2017-03-09 16:39 ` Tejun Heo [this message]
2017-03-09 10:16 ` [PATCH 2/4] bdi: Fix use-after-free in wb_congested_put() Jan Kara
2017-03-09 10:16 ` [PATCH 3/4] block: Make del_gendisk() safer for disks without queues Jan Kara
2017-03-09 10:16 ` [PATCH 4/4] Revert "scsi, block: fix duplicate bdi name registration crashes" Jan Kara
2017-03-09 16:41 ` [PATCH 0/4 v2] block: Fixes for bdi handling Jens Axboe
2017-03-10 10:22 ` Jan Kara
2017-03-11 22:27 ` Jens Axboe
-- strict thread matches above, loose matches on Subject: below --
2017-03-08 16:48 [PATCH 0/4] " Jan Kara
2017-03-08 16:48 ` [PATCH 1/4] block: Allow bdi re-registration Jan Kara
2017-03-08 22:55 ` Tejun Heo
2017-03-08 23:17 ` James Bottomley
2017-03-09 9:10 ` Jan Kara
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