On 6/05/20 5:34 pm, Veerabhadrarao Badiganti wrote:
From: Sarthak Garg sartgarg@codeaurora.org
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@vger.kernel.org # v4.19+ Suggested-by: Sahitya Tummala stummala@codeaurora.org Signed-off-by: Sarthak Garg sartgarg@codeaurora.org
drivers/mmc/core/queue.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c index 25bee3d..72bef39 100644 --- a/drivers/mmc/core/queue.c +++ b/drivers/mmc/core/queue.c @@ -107,7 +107,7 @@ static enum blk_eh_timer_return mmc_cqe_timed_out(struct request *req) case MMC_ISSUE_DCMD: if (host->cqe_ops->cqe_timeout(host, mrq, &recovery_needed)) { if (recovery_needed)
__mmc_cqe_recovery_notifier(mq);
mmc_cqe_recovery_notifier(mrq); return BLK_EH_RESET_TIMER;@@ -131,12 +131,13 @@ static enum blk_eh_timer_return mmc_mq_timed_out(struct request *req, spin_lock_irqsave(&mq->lock, flags);
- if (mq->recovery_needed || !mq->use_cqe || host->hsq_enabled)
- if (mq->recovery_needed || !mq->use_cqe || host->hsq_enabled) { ret = BLK_EH_RESET_TIMER;
- else
spin_unlock_irqrestore(&mq->lock, flags);- } else {
spin_unlock_irqrestore(&mq->lock, flags);
- spin_unlock_irqrestore(&mq->lock, flags);
- }
This looks good, but I think there needs to be another change also. I will send a patch for that, but in the meantime maybe you could straighten up the code flow through the spinlock e.g.
spin_lock_irqsave(&mq->lock, flags); ignore = mq->recovery_needed || !mq->use_cqe || host->hsq_enabled; spin_unlock_irqrestore(&mq->lock, flags);
return ignore ? BLK_EH_RESET_TIMER : mmc_cqe_timed_out(req);
And add a fixes tag.
return ret; }