Re: request for 4.14-stable: 1dc3039bc87a ("block: do not use interruptible wait anywhere")

[Alan Jenkins <alan.christopher.jenkins@gmail.com>]

On 20/07/18 11:26, Sudip Mukherjee wrote:
> Hi Alan,
> My thought was that since you said "or" in your commit message:
> "When blk_queue_enter() waits for a queue to unfreeze, or unset the
> PREEMPT_ONLY flag, do not allow it to be interrupted by a signal", so
> the fault condition can be when it is waiting on the queue and is
> interrupted. So even though 'PREEMPT_ONLY' is not there in v4.14.y, we
> can see the problem just because of getting interrupted while on queue.
>
> Plesase correct me if I was wrong.

You're absolutely right.

I suppose the original commit message might not be quite as clear when 
added in 4.14.x, so I had biased against that a bit.

pre-v4.15 doesn't fail the suspend test in the commit message, but a 
test was added to blktests afterwards, which should exactly cover the 
"or" part.

https://github.com/osandov/blktests/blob/master/tests/block/016

>> IIUC, the bugfix could be applied to *three* of the "longterm" kernel lines:
>> 4.14.56, 4.9.113, 4.4.142.  Since the commit says this bug was introduced to
>> the single-queue block layer in v4.4, commit 3ef28e8 ("block: generic
>> request_queue reference counting").
> I will send the backport for v4.9.y and v4.4.y also.