Re: (subset) [PATCH 00/11] remove aux CQE caches

[Ming Lei <ming.lei@redhat.com>]

On Sat, Mar 16, 2024 at 10:04 AM Ming Lei <ming.lei@redhat.com> wrote:
>
> On Fri, Mar 15, 2024 at 04:53:21PM -0600, Jens Axboe wrote:
> >
> > On Fri, 15 Mar 2024 15:29:50 +0000, Pavel Begunkov wrote:
> > > Patch 1 is a fix.
> > >
> > > Patches 2-7 are cleanups mainly dealing with issue_flags conversions,
> > > misundertsandings of the flags and of the tw state. It'd be great to have
> > > even without even w/o the rest.
> > >
> > > 8-11 mandate ctx locking for task_work and finally removes the CQE
> > > caches, instead we post directly into the CQ. Note that the cache is
> > > used by multishot auxiliary completions.
> > >
> > > [...]
> >
> > Applied, thanks!
>
> Hi Jens and Pavel,
>
> Looks this patch causes hang when running './check ublk/002' in blktests.

Not take close look, and  I guess it hangs in

io_uring_cmd_del_cancelable() -> io_ring_submit_lock

[root@ktest-36 ~]# cat /proc/1420/stack
[<0>] io_uring_cmd_done+0x161/0x1c0
[<0>] ublk_stop_dev+0x10e/0x1b0 [ublk_drv]
[<0>] ublk_ctrl_uring_cmd+0xbc9/0x11e0 [ublk_drv]
[<0>] io_uring_cmd+0x9e/0x130
[<0>] io_issue_sqe+0x2d3/0x730
[<0>] io_wq_submit_work+0xd2/0x350
[<0>] io_worker_handle_work+0x12a/0x4b0
[<0>] io_wq_worker+0x101/0x390
[<0>] ret_from_fork+0x31/0x50
[<0>] ret_from_fork_asm+0x1a/0x30

(gdb) l *(io_uring_cmd_done+0x161)
0xffffffff817ed241 is in io_uring_cmd_done (./include/linux/list.h:985).
980 return !READ_ONCE(h->first);
981 }
982
983 static inline void __hlist_del(struct hlist_node *n)
984 {
985 struct hlist_node *next = n->next;
986 struct hlist_node **pprev = n->pprev;
987
988 WRITE_ONCE(*pprev, next);
989 if (next)


Thanks,