Re: [4.19.124 V1] mmc: core: Fix recursive locking issue in CQE recovery path

[Greg KH]

On Wed, May 27, 2020 at 05:49:02PM +0530, Sarthak Garg wrote:
> [ Upstream commit 39a22f73744d5baee30b5f134ae2e30b668b66ed ]
> 
> Consider the following stack trace
> 
> -001|raw_spin_lock_irqsave
> -002|mmc_blk_cqe_complete_rq
> -003|__blk_mq_complete_request(inline)
> -003|blk_mq_complete_request(rq)
> -004|mmc_cqe_timed_out(inline)
> -004|mmc_mq_timed_out
> 
> mmc_mq_timed_out acquires the queue_lock for the first
> time. The mmc_blk_cqe_complete_rq function also tries to acquire
> the same queue lock resulting in recursive locking where the task
> is spinning for the same lock which it has already acquired leading
> to watchdog bark.
> 
> Fix this issue with the lock only for the required critical section.
> 
> Cc: <stable@xxxxxxxxxxxxxxx>
> Fixes: 1e8e55b67030 ("mmc: block: Add CQE support")
> Suggested-by: Sahitya Tummala <stummala@xxxxxxxxxxxxxx>
> Signed-off-by: Sarthak Garg <sartgarg@xxxxxxxxxxxxxx>
> Acked-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> Link: https://lore.kernel.org/r/1588868135-31783-1-git-send-email-vbadigan@xxxxxxxxxxxxxx
> Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
> ---

Thanks for the backport, now queued up.

greg k-h