Re: regression caused by block: freeze the queue earlier in del_gendisk

Thorsten Leemhuis
2022-08-31T12:36:43Z

[CCing the mdraid maintainer and the raid ml to keep them in the loop]

Hi, this is your Linux kernel regression tracker. Top-posting for once,
to make this easily accessible to everyone.

Christoph, Jens, what's up here? Dusty bisected this and even confirmed
a revert on-top of current mainline fixes things for him, nevertheless
he didn't get a single reply since he reported the issue last Friday.

BTW, it seems quite a few Fedora users are now hitting this with the
slightly patched Fedora 5.19.y kernels they since a few days ship as
regular update, as comments in
https://bugzilla.redhat.com/show_bug.cgi?id=2121791 show -- so it seems
it's not something specific to Dusty's setup.

Could you please look into the issue? tia!

Ciao, Thorsten

On 28.08.22 12:24, Thorsten Leemhuis wrote:
> Hi, this is your Linux kernel regression tracker. Thx for the report.
>
> CCing the regression mailing list, as it should be in the loop for all
> regressions, as explained here:
> https://www.kernel.org/doc/html/latest/admin-guide/reporting-issues.html
>
> On 26.08.22 18:15, Dusty Mabe wrote:
>>
>> I think I've found a regression introduced by:
>> a09b314 o block: freeze the queue earlier in del_gendisk
>
> Just FYI, in case you are not aware of it already: there was another
> report that this commit causes problems. See this thread for details:
> https://lore.kernel.org/all/72a5bf2e-cd56-a85c-2b99-cb8729a66fed@deltatee.com/#t
>
> Anyway, let me add this report to the regressions tracking:
>
> [TLDR: I'm adding this regression report to the list of tracked
> regressions; all text from me you find below is based on a few templates
> paragraphs you might have encountered already already in similar form.]
>
>> In Fedora CoreOS we have tests that set up RAID1 on the /boot/ and /root/ partitions
>> and then subsequently removes one of the disks to simulate a failure. Sometime recently
>> this test started timing out occasionally. Looking a bit closer it appears instances are
>> getting stuck during reboot with a bunch of looping messages:
>>
>> ```
>> [ 17.978854] block device autoloading is deprecated and will be removed.
>> [ 17.982555] block device autoloading is deprecated and will be removed.
>> [ 17.985537] block device autoloading is deprecated and will be removed.
>> [ 17.987546] block device autoloading is deprecated and will be removed.
>> [ 17.989540] block device autoloading is deprecated and will be removed.
>> [ 17.991547] block device autoloading is deprecated and will be removed.
>> [ 17.993555] block device autoloading is deprecated and will be removed.
>> [ 17.995539] block device autoloading is deprecated and will be removed.
>> [ 17.997577] block device autoloading is deprecated and will be removed.
>> [ 17.999544] block device autoloading is deprecated and will be removed.
>> [ 22.979465] blkdev_get_no_open: 1666 callbacks suppressed
>> ...
>> ...
>> ...
>> [ 618.221270] blkdev_get_no_open: 1664 callbacks suppressed
>> [ 618.221273] block device autoloading is deprecated and will be removed.
>> [ 618.224274] block device autoloading is deprecated and will be removed.
>> [ 618.227267] block device autoloading is deprecated and will be removed.
>> [ 618.229274] block device autoloading is deprecated and will be removed.
>> [ 618.231277] block device autoloading is deprecated and will be removed.
>> [ 618.233277] block device autoloading is deprecated and will be removed.
>> [ 618.235282] block device autoloading is deprecated and will be removed.
>> [ 618.237370] block device autoloading is deprecated and will be removed.
>> [ 618.239356] block device autoloading is deprecated and will be removed.
>> [ 618.241290] block device autoloading is deprecated and will be removed.
>> ```
>>
>> Using the Fedora kernels I narrowed it down to being introduced between
>> `kernel-5.19.0-0.rc3.27.fc37` (good) and `kernel-5.19.0-0.rc4.33.fc37` (bad).
>>
>> I then did a bisect and found:
>>
>> ```
>> $ git bisect bad
>> a09b314005f3a0956ebf56e01b3b80339df577cc is the first bad commit
>> commit a09b314005f3a0956ebf56e01b3b80339df577cc
>> Author: Christoph Hellwig <hch@lst.de>
>> Date: Tue Jun 14 09:48:27 2022 +0200
>>
>> block: freeze the queue earlier in del_gendisk
>>
>> Freeze the queue earlier in del_gendisk so that the state does not
>> change while we remove debugfs and sysfs files.
>>
>> Ming mentioned that being able to observer request in debugfs might
>> be useful while the queue is being frozen in del_gendisk, which is
>> made possible by this change.
>>
>> Signed-off-by: Christoph Hellwig <hch@lst.de>
>> Link: https://lore.kernel.org/r/20220614074827.458955-5-hch@lst.de
>> Signed-off-by: Jens Axboe <axboe@kernel.dk>
>>
>> block/genhd.c | 3 +--
>> 1 file changed, 1 insertion(+), 2 deletions(-)
>> ```
>>
>> Reverting this commit on top of latest git master (4c612826b) gave me successful results.
>>
>> Any ideas on what could be amiss here? Luckily the patch is tiny so hopefully it might
>> be obvious.
>>
>> More details (including logs) in the following locations:
>>
>> - https://bugzilla.redhat.com/show_bug.cgi?id=2121791
>> - https://github.com/coreos/fedora-coreos-tracker/issues/1282
>>
>>
>> Thanks!
>> Dusty
>>
>
> Thanks for the report. To be sure below issue doesn't fall through the
> cracks unnoticed, I'm adding it to regzbot, my Linux kernel regression
> tracking bot:
>
> #regzbot ^introduced a09b314005f3a0
> #regzbot title block: timeouts when removing a disk from a RAID1
> #regzbot ignore-activity
>
> This isn't a regression? This issue or a fix for it are already
> discussed somewhere else? It was fixed already? You want to clarify when
> the regression started to happen? Or point out I got the title or
> something else totally wrong? Then just reply -- ideally with also
> telling regzbot about it, as explained here:
> https://linux-regtracking.leemhuis.info/tracked-regression/
>
> Reminder for developers: When fixing the issue, add 'Link:' tags
> pointing to the report (the mail this one replies to), as explained for
> in the Linux kernel's documentation; above webpage explains why this is
> important for tracked regressions.
>
> Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
>
> P.S.: As the Linux kernel's regression tracker I deal with a lot of
> reports and sometimes miss something important when writing mails like
> this. If that's the case here, don't hesitate to tell me in a public
> reply, it's in everyone's interest to set the public record straight.

BTW:

#regzbot link: https://bugzilla.redhat.com/show_bug.cgi?id=2121791
#regzbot poke