[Bug 215880] Resume process hangs for 5-6 seconds starting sometime in 5.16

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=215880

--- Comment #37 from Bart Van Assche (bvanassche@acm.org) ---
On 8/25/22 13:01, bugzilla-daemon@kernel.org wrote:
> https://bugzilla.kernel.org/show_bug.cgi?id=215880
> 
> --- Comment #36 from jason600 (jason600.groome@gmail.com) ---
> (In reply to Bart Van Assche from comment #27)
>> Thanks for testing! The patches from the sd-resume branch have been posted
>> on the linux-scsi mailing list. See also
>>
>> https://lore.kernel.org/linux-scsi/20220628222131.14780-1-bvanassche@acm.org/
>> T/#t
> 
> Hi Bart, just an update for you. I noticed this had been removed from the
> 6.0-rc1 for freezing after suspend.
> 
> I've been compiling my kernel with this fix on various 5.18 kernels (with
> opensuse tumbleweed), it has worked fine, no freezing on resume as others
> have
> mentioned.
> 
> Yesterday, I updated to 5.19.2 kernel, applied the fix, recompiled, and it
> froze after the first suspend. Rebooted and the same thing happened again. I
> recompiled the kernel with the fix, just to make sure i didn't mess it up,
> and
> the same happened again.
> 
> When you originally did this fix, you based it on 5.18, and indeed, it works
> fine on 5.18 for me. There were a lot of changes to the drivers/scsi/sd.c
> file
> for 5.19, presumably it was those changes that made this fix start freezing
> after suspend.
> 
> Perhaps you could check if the other people that experienced freezing were
> using either 5.19 or 6.0-rc1.

Multiple people reported issues with freezes during suspend with kernel 
v6.0-rc1. Please take a look at the following report: 
https://lore.kernel.org/all/dd6844e7-f338-a4e9-2dad-0960e25b2ca1@redhat.com/. 
It shows that if zoned ATA disks are present that blk_mq_freeze_queue() 
may be called from inside ata_scsi_dev_rescan() on the context of a work 
queue. ATA rescanning happens from inside the SCSI error handler. So 
there is potential for a lockup because of the following:
* Execution of the START command being postponed because the SCSI error 
handler is active.
* blk_mq_freeze_queue() waiting for the START command to finish.
* The START completion handler not being executed because it got queued 
on the same work queue as the ATA rescan work.

Unfortunately I do not know enough about the ATA core to proceed. I need 
help from an ATA expert.

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