Re: [PATCH V2] block: Prevent hung_check firing during long sync IO

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

On Wed, Mar 18, 2020 at 11:55:09AM +0100, Guoqing Jiang wrote:
> Hi Ming,
> 
> On 3/18/20 4:43 AM, Ming Lei wrote:
> > submit_bio_wait() can be called from ioctl(BLKSECDISCARD), which
> > may take long time to complete, as Salman mentioned, 4K BLKSECDISCARD
> > takes up to 100 second on some devices. Also any block I/O operation
> > that occurs after the BLKSECDISCARD is submitted will also potentially
> > be affected by the hung task timeouts.
> > 
> > Another report is that task hang can be observed when running mkfs
> > over raid10 which takes a small max discard sectors limit because
> > of chunk size.
> 
> Could you point the link about the raid10 task hang? And we have observed
> task hang with raid5, not sure it is related or not.
> 
> Our set up is md/raid5 -> 100+ LVs (fs is created on top of one LV), run heavy
> IOs on LVs and dbench on the LV with fs, then dbench hangs with 'D' state.

Red Hat Bugzilla 1813383.


Thanks,
Ming