On Tue, Feb 28, 2017 at 11:25:28PM -0800, Omar Sandoval wrote:

On Wed, Feb 22, 2017 at 11:24:25AM +0100, Jan Kara wrote:

quoted

On Tue 21-02-17 10:19:28, Jens Axboe wrote:

quoted

On 02/21/2017 10:09 AM, Jan Kara wrote:

quoted

Hello,

this is a second revision of the patch set to fix several different races and
issues I've found when testing device shutdown and reuse. The first three
patches are fixes to problems in my previous series fixing BDI lifetime issues.
Patch 4 fixes issues with reuse of BDI name with scsi devices. With it I cannot
reproduce the BDI name reuse issues using Omar's stress test using scsi_debug
so it can be used as a replacement of Dan's patches. Patches 5-11 fix oops that
is triggered by __blkdev_put() calling inode_detach_wb() too early (the problem
reported by Thiago). Patches 12 and 13 fix oops due to a bug in gendisk code
where get_gendisk() can return already freed gendisk structure (again triggered
by Omar's stress test).

People, please have a look at patches. They are mostly simple however the
interactions are rather complex so I may have missed something. Also I'm
happy for any additional testing these patches can get - I've stressed them
with Omar's script, tested memcg writeback, tested static (not udev managed)
device inodes.

Jens, I think at least patches 1-3 should go in together with my fixes you
already have in your tree (or shortly after them). It is up to you whether
you decide to delay my first fixes or pick these up quickly. Patch 4 is
(IMHO a cleaner) replacement of Dan's patches so consider whether you want
to use it instead of those patches.

I have applied 1-3 to my for-linus branch, which will go in after
the initial pull request has been pulled by Linus. Consider fixing up
#4 so it applies, I like it.

OK, attached is patch 4 rebased on top of Linus' tree from today which
already has linux-block changes pulled in. I've left put_disk_devt() in
blk_cleanup_queue() to maintain the logic in the original patch (now commit
0dba1314d4f8) that request_queue and gendisk each hold one devt reference.
The bdi_unregister() call that is moved to del_gendisk() by this patch is
now protected by the gendisk reference instead of the request_queue one
so it still maintains the property that devt reference protects bdi
registration-unregistration lifetime (as much as that is not needed anymore
after this patch).

I have also updated the comment in the code and the changelog - they were
somewhat stale after changes to the whole series Tejun suggested.

								Honza

Hey, Jan, I just tested this out when I was seeing similar crashes with
sr instead of sd, and this fixed it.

Tested-by: Omar Sandoval <redacted>

Just realized it wasn't clear, I'm talking about patch 4 specifically.