On Tue, Feb 18, 2020 at 6:55 PM Ming Lei [off-list ref] wrote:

On Tue, Feb 18, 2020 at 08:11:53AM -0800, Jesse Barnes wrote:

quoted

On Fri, Feb 14, 2020 at 7:47 PM Ming Lei [off-list ref] wrote:

quoted

What are the 'other operations'? Are they block IOs?

If yes, that is why I suggest to fix submit_bio_wait(), which should cover
most of sync bio submission.

Anyway, the fix is simple & generic enough, I'd plan to post a formal
patch if no one figures out better doable approaches.

Yeah I think any block I/O operation that occurs after the
BLKSECDISCARD is submitted will also potentially be affected by the
hung task timeouts, and I think your patch will address that.  My only
concern with it is that it might hide some other I/O "hangs" that are
due to device misbehavior instead.  Yes driver and device timeouts
should generally catch those, but with this in place we might miss a
few bugs.

Given the nature of these types of storage devices though, I think
that's a minor issue and not worth blocking the patch on, given that
it should prevent a lot of false positive hang reports as Salman
demonstrated.

Hello Jesse and Salman,

One more question about this issue, do you enable BLK_WBT on your test
kernel?

It doesn't exist on the original 4.4-based kernel where we reproduced
this bug.  I am curious how this interacts with this bug.

Thanks,
Ming