* request for 4.14-stable: 1dc3039bc87a ("block: do not use interruptible wait anywhere")
@ 2018-07-19 22:09 Sudip Mukherjee
2018-07-20 7:26 ` Greg Kroah-Hartman
2018-07-20 8:37 ` Alan Jenkins
0 siblings, 2 replies; 5+ messages in thread
From: Sudip Mukherjee @ 2018-07-19 22:09 UTC (permalink / raw)
To: Greg Kroah-Hartman; +Cc: Bart Van Assche, stable, Alan Jenkins, Jens Axboe
[-- Attachment #1: Type: text/plain, Size: 89 bytes --]
Hi Greg,
This was missing in 4.14-stable. Please apply to your queue.
--
Regards
Sudip
[-- Attachment #2: 0001-block-do-not-use-interruptible-wait-anywhere.patch --]
[-- Type: text/x-diff, Size: 2478 bytes --]
>From d82c7fab69ca2f088c41af99959e37dd3ee76d1d Mon Sep 17 00:00:00 2001
From: Alan Jenkins <alan.christopher.jenkins@gmail.com>
Date: Thu, 12 Apr 2018 19:11:58 +0100
Subject: [PATCH] block: do not use interruptible wait anywhere
commit 1dc3039bc87ae7d19a990c3ee71cfd8a9068f428 upstream
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.
The PREEMPT_ONLY flag was introduced later in commit 3a0a529971ec
("block, scsi: Make SCSI quiesce and resume work reliably"). Note the SCSI
device is resumed asynchronously, i.e. after un-freezing userspace tasks.
So that commit exposed the bug as a regression in v4.15. A mysterious
SIGBUS (or -EIO) sometimes happened during the time the device was being
resumed. Most frequently, there was no kernel log message, and we saw Xorg
or Xwayland killed by SIGBUS.[1]
[1] E.g. https://bugzilla.redhat.com/show_bug.cgi?id=1553979
Without this fix, I get an IO error in this test:
while killall -SIGUSR1 dd; do sleep 0.1; done & \
echo mem > /sys/power/state ; \
sleep 5; killall dd # stop after 5 seconds
The interruptible wait was added to blk_queue_enter in
commit 3ef28e83ab15 ("block: generic request_queue reference counting").
Before then, the interruptible wait was only in blk-mq, but I don't think
it could ever have been correct.
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: stable@vger.kernel.org
Signed-off-by: Alan Jenkins <alan.christopher.jenkins@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
---
block/blk-core.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index 6f6e21821d2d..68bae6338ad4 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -779,7 +779,6 @@ EXPORT_SYMBOL(blk_alloc_queue);
int blk_queue_enter(struct request_queue *q, bool nowait)
{
while (true) {
- int ret;
if (percpu_ref_tryget_live(&q->q_usage_counter))
return 0;
@@ -796,13 +795,11 @@ int blk_queue_enter(struct request_queue *q, bool nowait)
*/
smp_rmb();
- ret = wait_event_interruptible(q->mq_freeze_wq,
- !atomic_read(&q->mq_freeze_depth) ||
- blk_queue_dying(q));
+ wait_event(q->mq_freeze_wq,
+ !atomic_read(&q->mq_freeze_depth) ||
+ blk_queue_dying(q));
if (blk_queue_dying(q))
return -ENODEV;
- if (ret)
- return ret;
}
}
--
2.11.0
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: request for 4.14-stable: 1dc3039bc87a ("block: do not use interruptible wait anywhere")
2018-07-19 22:09 request for 4.14-stable: 1dc3039bc87a ("block: do not use interruptible wait anywhere") Sudip Mukherjee
@ 2018-07-20 7:26 ` Greg Kroah-Hartman
2018-07-20 8:37 ` Alan Jenkins
1 sibling, 0 replies; 5+ messages in thread
From: Greg Kroah-Hartman @ 2018-07-20 7:26 UTC (permalink / raw)
To: Sudip Mukherjee; +Cc: Bart Van Assche, stable, Alan Jenkins, Jens Axboe
On Thu, Jul 19, 2018 at 11:09:36PM +0100, Sudip Mukherjee wrote:
> Hi Greg,
>
> This was missing in 4.14-stable. Please apply to your queue.
now applied, thanks.
greg k-h
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: request for 4.14-stable: 1dc3039bc87a ("block: do not use interruptible wait anywhere")
2018-07-19 22:09 request for 4.14-stable: 1dc3039bc87a ("block: do not use interruptible wait anywhere") Sudip Mukherjee
2018-07-20 7:26 ` Greg Kroah-Hartman
@ 2018-07-20 8:37 ` Alan Jenkins
2018-07-20 10:26 ` Sudip Mukherjee
1 sibling, 1 reply; 5+ messages in thread
From: Alan Jenkins @ 2018-07-20 8:37 UTC (permalink / raw)
To: Sudip Mukherjee; +Cc: Greg Kroah-Hartman, Bart Van Assche, stable, Jens Axboe
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?
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.
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").
Regards
Alan******
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: request for 4.14-stable: 1dc3039bc87a ("block: do not use interruptible wait anywhere")
2018-07-20 8:37 ` Alan Jenkins
@ 2018-07-20 10:26 ` Sudip Mukherjee
2018-07-20 11:09 ` Alan Jenkins
0 siblings, 1 reply; 5+ messages in thread
From: Sudip Mukherjee @ 2018-07-20 10:26 UTC (permalink / raw)
To: Alan Jenkins; +Cc: Greg Kroah-Hartman, Bart Van Assche, stable, Jens Axboe
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
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: request for 4.14-stable: 1dc3039bc87a ("block: do not use interruptible wait anywhere")
2018-07-20 10:26 ` Sudip Mukherjee
@ 2018-07-20 11:09 ` Alan Jenkins
0 siblings, 0 replies; 5+ messages in thread
From: Alan Jenkins @ 2018-07-20 11:09 UTC (permalink / raw)
To: Sudip Mukherjee; +Cc: Greg Kroah-Hartman, stable
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.
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2018-07-20 11:57 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2018-07-19 22:09 request for 4.14-stable: 1dc3039bc87a ("block: do not use interruptible wait anywhere") Sudip Mukherjee
2018-07-20 7:26 ` Greg Kroah-Hartman
2018-07-20 8:37 ` Alan Jenkins
2018-07-20 10:26 ` Sudip Mukherjee
2018-07-20 11:09 ` Alan Jenkins
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