On Wed, Oct 10, 2018 at 02:28:09PM +0200, Jan Kara wrote:

On Wed 10-10-18 13:42:27, Johannes Thumshirn wrote:

quoted

On Wed, Oct 10, 2018 at 07:19:00PM +0900, Tetsuo Handa wrote:

quoted

On 2018/10/10 19:04, Jan Kara wrote:

quoted

Hi,

this patch series fixes oops and possible deadlocks as reported by syzbot [1]
[2]. The second patch in the series (from Tetsuo) fixes the oops, the remaining
patches are cleaning up the locking in the loop driver so that we can in the
end reasonably easily switch to rereading partitions without holding mutex
protecting the loop device.

I have lightly tested the patches by creating, deleting, and modifying loop
devices but if there's some more comprehensive loopback device testsuite, I
can try running it. Review is welcome!

Testing on linux-next by syzbot will be the most comprehensive. ;-)

Apart from that blktests has a loop category and I think it could also be
worthwhile to add the C reproducer from syzkaller to blktests.

Yeah, I did run loop tests now and they ran fine. I can try converting the
syzbot reproducers into something legible but it will take a while.

There is one C repropducer which can be used (it just needs minor
modifications to pass in the device instead of loop0).

See for instance blktests/src/sg/syzkaller1.c

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