From: "Linux regression tracking #update (Thorsten Leemhuis)" <regressions@leemhuis.info>
To: "Richard W.M. Jones" <rjones@redhat.com>,
Aaron Thompson <dev@aaront.org>,
Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org,
Linux kernel regressions list <regressions@lists.linux.dev>
Subject: Re: printk.time causes rare kernel boot hangs
Date: Sun, 18 Jun 2023 12:25:35 +0200 [thread overview]
Message-ID: <1413638e-9614-056e-cfc5-5f9c8bf8af00@leemhuis.info> (raw)
In-Reply-To: <172193eb-14cc-549e-2953-6749a3a4c502@leemhuis.info>
On 13.06.23 16:07, Linux regression tracking #adding (Thorsten Leemhuis)
wrote:
>
> On 13.06.23 15:41, Richard W.M. Jones wrote:
>> [Being tracked in this bug which contains much more detail:
>> https://gitlab.com/qemu-project/qemu/-/issues/1696 ]
>>
>> Recent kernels hang rarely when booted on qemu. Usually you need to
>> boot 100s or 1,000s of times to see the hang, compared to 292,612 [sic]
>> successful boots which I was able to do before the problematic commit.
>>
>> A reproducer (you'll probably need to use Fedora) is:
>>
>> $ while guestfish -a /dev/null -v run >& /tmp/log; do echo -n . ; done
>>
>> You will need to leave it running for probably several hours, and
>> examine the /tmp/log file at the end.
>>
>> I tracked this down to the following commit:
>>
>> commit f31dcb152a3d0816e2f1deab4e64572336da197d
>> Author: Aaron Thompson <dev@aaront.org>
>> Date: Thu Apr 13 17:50:12 2023 +0000
>>
>> sched/clock: Fix local_clock() before sched_clock_init()
>>
>> Have local_clock() return sched_clock() if sched_clock_init() has not
>> yet run. sched_clock_cpu() has this check but it was not included in the
>> new noinstr implementation of local_clock().
>>
>> (https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=f31dcb152a3d0816e2f1deab4e64572336da197d)
>>
>> Reverting this commit fixes the problem.
>>
>> I don't know _why_ this commit is wrong, but can we revert it as it
>> causes serious problems with libguestfs hanging randomly.
>>
>> Or if there's anything you want me to try out then let me know,
>> because I can reproduce the problem locally quite easily.
>
> Thanks for the report. To be sure the issue doesn't fall through the
> cracks unnoticed, I'm adding it to regzbot, the Linux kernel regression
> tracking bot:
>
> #regzbot ^introduced f31dcb152a3d0816e2f1deab4e64572336da197d
> #regzbot title sched/clock: printk.time causes rare kernel boot hangs
> #regzbot ignore-activity
#regzbot fix: tick/common: Align tick period during sched_timer setup
#regzbot monitor:
https://lore.kernel.org/all/12c6f9a3-d087-b824-0d05-0d18c9bc1bf3@amazon.com/
#regzbot ignore-activity
Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
--
Everything you wanna know about Linux kernel regression tracking:
https://linux-regtracking.leemhuis.info/about/#tldr
That page also explains what to do if mails like this annoy you.
next prev parent reply other threads:[~2023-06-18 10:25 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-13 13:41 printk.time causes rare kernel boot hangs Richard W.M. Jones
2023-06-13 14:07 ` Linux regression tracking #adding (Thorsten Leemhuis)
2023-06-18 10:25 ` Linux regression tracking #update (Thorsten Leemhuis) [this message]
2023-06-14 9:21 ` Peter Zijlstra
2023-06-14 9:45 ` Richard W.M. Jones
2023-06-14 10:30 ` Richard W.M. Jones
2023-06-14 10:39 ` Richard W.M. Jones
2023-06-14 11:35 ` Peter Zijlstra
2023-06-14 11:43 ` Richard W.M. Jones
2023-06-14 12:37 ` Richard W.M. Jones
2023-06-14 12:53 ` Peter Zijlstra
2023-06-14 13:03 ` Richard W.M. Jones
2023-06-14 13:09 ` Peter Zijlstra
2023-06-14 14:53 ` Peter Zijlstra
2023-06-14 15:07 ` Richard W.M. Jones
2023-06-14 15:19 ` Peter Zijlstra
2023-06-14 15:22 ` Richard W.M. Jones
2023-06-14 15:31 ` Peter Zijlstra
2023-06-14 15:50 ` Richard W.M. Jones
2023-06-14 17:34 ` Richard W.M. Jones
2023-06-15 7:40 ` Alexandre Belloni
2023-06-15 7:48 ` Richard W.M. Jones
2023-06-14 11:20 ` Peter Zijlstra
2023-06-14 11:16 ` Peter Zijlstra
2023-06-14 11:22 ` Richard W.M. Jones
2023-06-14 11:26 ` Richard W.M. Jones
2023-06-15 11:04 ` YiFei Zhu
2023-06-15 11:29 ` Richard W.M. Jones
2023-06-15 11:31 ` Richard W.M. Jones
2023-06-15 12:20 ` Dr. David Alan Gilbert
2023-06-15 12:21 ` Richard W.M. Jones
2023-06-15 12:23 ` Richard W.M. Jones
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