On Sun, Feb 17, 2019 at 04:37:29PM +0100, Thibaut Sautereau wrote:
On Wed, Jan 30, 2019 at 08:54:09AM -0700, Jens Axboe wrote:
On 1/30/19 2:01 AM, Jianchao Wang wrote:
> Florian reported a io hung issue when fsync(). It should be
> triggered by following race condition.
>
> data + post flush a flush
>
> blk_flush_complete_seq
> case REQ_FSEQ_DATA
> blk_flush_queue_rq
> issued to driver blk_mq_dispatch_rq_list
> try to issue a flush req
> failed due to NON-NCQ command
> .queue_rq return BLK_STS_DEV_RESOURCE
>
> request completion
> req->end_io // doesn't check RESTART
> mq_flush_data_end_io
> case REQ_FSEQ_POSTFLUSH
> blk_kick_flush
> do nothing because previous flush
> has not been completed
> blk_mq_run_hw_queue
> insert rq to hctx->dispatch
> due to RESTART is still set, do nothing
>
> To fix this, replace the blk_mq_run_hw_queue in mq_flush_data_end_io
> with blk_mq_sched_restart to check and clear the RESTART flag.
Applied, thanks.
--
Jens Axboe
Can this be applied to stable kernels please?
It's commit 85bd6e61f34dffa8ec2dc75ff3c02ee7b2f1cbce upstream.
I've queued it for 4.20, 4.19 and 4.14.
--
Thanks,
Sasha
