[BUG] block: sx8: Invalid wait context in carm_queue_rq()

[BUG] block: sx8: Invalid wait context in carm_queue_rq()

[Zheyu Ma]

Hi,

I found a bug in the sx8 driver when probing this driver.
I have no idea about how this happened, it seems like a misuse of the lock.

With LOCKDEP=y, the following log can reveal it:

[    3.403123] =============================
[    3.403205] [ BUG: Invalid wait context ]
[    3.403205] 5.16.0-rc1+ #29 Not tainted
[    3.403205] -----------------------------
[    3.403205] kworker/5:1/68 is trying to lock:
[    3.403205] ffff888012c80060 (&entry->access){+.+.}-{3:3}, at:
carm_queue_rq+0x110/0x1290
[    3.403205] other info that might help us debug this:
[    3.403205] context-{4:4}
[    3.403205] 3 locks held by kworker/5:1/68:
[    3.403205]  #0: ffff888100068d38
((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x644/0xaf0
[    3.403205]  #1: ffff888105f17d68
((work_completion)(&host->fsm_task)){+.+.}-{0:0}, at:
process_one_work+0x68c/0xaf0
[    3.403205]  #2: ffffffff8e441b60 (rcu_read_lock){....}-{1:2}, at:
rcu_lock_acquire+0x0/0x20
[    3.403205] stack backtrace:
[    3.403205] CPU: 5 PID: 68 Comm: kworker/5:1 Not tainted 5.16.0-rc1+ #29
[    3.403205] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009),
BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
[    3.403205] Workqueue: events carm_fsm_task
[    3.403205] Call Trace:
[    3.403205]  <TASK>
[    3.403205]  dump_stack_lvl+0x5d/0x78
[    3.403205]  __lock_acquire+0x144a/0x1e20
[    3.403205]  lock_acquire+0x101/0x2d0
[    3.403205]  ? carm_queue_rq+0x110/0x1290
[    3.403205]  _raw_spin_lock+0x2a/0x40
[    3.403205]  ? carm_queue_rq+0x110/0x1290
[    3.403205]  carm_queue_rq+0x110/0x1290
[    3.403205]  ? __blk_mq_get_driver_tag+0x2da/0x780
[    3.403205]  blk_mq_dispatch_rq_list+0xcd0/0x24f0
[    3.403205]  ? rcu_read_lock_sched_held+0x2f/0x70
[    3.403205]  ? lock_release+0x47e/0x720
[    3.403205]  __blk_mq_sched_dispatch_requests+0x2f8/0x3a0
[    3.403205]  blk_mq_sched_dispatch_requests+0xc1/0xf0
[    3.403205]  __blk_mq_run_hw_queue+0x86/0xe0
[    3.403205]  __blk_mq_delay_run_hw_queue+0x1b3/0x490
[    3.403205]  ? rcu_lock_acquire+0x20/0x20
[    3.403205]  blk_mq_run_hw_queue+0x137/0x300
[    3.403205]  blk_mq_sched_insert_request+0x13e/0x2c0
[    3.403205]  process_one_work+0x6d8/0xaf0
[    3.403205]  worker_thread+0x9bd/0x14a0
[    3.403205]  kthread+0x38b/0x470
[    3.403205]  ? rcu_lock_release+0x20/0x20
[    3.403205]  ? kthread_unuse_mm+0x170/0x170
[    3.403205]  ret_from_fork+0x22/0x30
[    3.403205]  </TASK>

Regards,
Zheyu Ma

Re: [BUG] block: sx8: Invalid wait context in carm_queue_rq()

[Christoph Hellwig]

I guess you don't actually have the hardware and just built it into the
kernel?

Because I've been pretty sure that this driver is pretty much dead,
so maybe we need to go ahead and just remove it.

Re: [BUG] block: sx8: Invalid wait context in carm_queue_rq()

[Zheyu Ma]

On Wed, Mar 9, 2022 at 2:30 PM Christoph Hellwig <hch@infradead.org> wrote:
>
> I guess you don't actually have the hardware and just built it into the
> kernel?

Yes, I use the virtual machine instead of the real hardware.

> Because I've been pretty sure that this driver is pretty much dead,
> so maybe we need to go ahead and just remove it.

I found that there were a few active commits to this driver last year,
so I assumed it was still "alive".
Maybe it's time to clean up these unused drivers.

Thanks,
Zheyu Ma