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

[Sudip Mukherjee <sudipm.mukherjee@gmail.com>]

Hi Alan,

On Fri, Jul 20, 2018 at 09:37:29AM +0100, Alan Jenkins wrote:
> On 19/07/18 23:09, Sudip Mukherjee wrote:
> > Hi Greg,
> > 
> > This was missing in 4.14-stable. Please apply to your queue.
> > 
> > --
> > Regards
> > Sudip
> 
> Hi Sudip,
> 
> This is correct, seems low-risk, and I don't mind it going ahead. But I'm
> curious� why you're interested in it for v4.14.� Mostly, I wonder if the
> same reason would apply to older kernels as well?

Well, since I have to use v4.14.y for my dayjob I will like to see all
possible fixes landing in 4.14-stable. That makes my dayjob a little
easier. :)

> 
> While the bugfix is applicable to v4.14, the nasty X crash on suspend is
> only on v4.15 and v4.16.� I think I left it to other's judgement, as to
> whether the bugfix would be wanted outside that case.

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.

> 
> 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.

--
Regards
Sudip