Re: [RFC PATCH v2 0/2] block: fix backing_dev_info lifetime

From: Dan Williams
Date: Wed Jan 25 2017 - 16:44:05 EST

On Mon, Jan 23, 2017 at 1:17 PM, Thiago Jung Bauermann
<bauerman@xxxxxxxxxxxxxxxxxx> wrote:
> Hello Dan,
> Am Freitag, 6. Januar 2017, 17:02:51 BRST schrieb Dan Williams:
>> v1 of these changes [1] was a one line change to bdev_get_queue() to
>> prevent a shutdown crash when del_gendisk() races the final
>> __blkdev_put().
>> While it is known at del_gendisk() time that the queue is still alive,
>> Jan Kara points to other paths [2] that are racing __blkdev_put() where
>> the assumption that ->bd_queue, or inode->i_wb is valid does not hold.
>> Fix that broken assumption, make it the case that if you have a live
>> block_device, or block_device-inode that the corresponding queue and
>> inode-write-back data is still valid.
>> These changes survive a run of the libnvdimm unit test suite which puts
>> some stress on the block_device shutdown path.
> I realize that the kernel test robot found problems with this series, but FWIW
> it fixes the bug mentioned in [2].

Thanks for the test result. I might take a look at cleaning up the
test robot reports and resubmitting this approach unless Jan beats me
to the punch with his backing_devi_info lifetime change patches.

>> [2]: