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Date:   Fri, 7 Jul 2023 12:13:11 +0200
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Subject: Re: Fwd: vmalloc error: btrfs-delalloc btrfs_work_helper [btrfs] in
 kernel 6.3.x
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To:     Linux regressions mailing list <regressions@lists.linux.dev>,
        Uladzislau Rezki <urezki@gmail.com>,
        Bagas Sanjaya <bagasdotme@gmail.com>
Cc:     Linux btrfs <linux-btrfs@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux Stable <stable@vger.kernel.org>,
        Chris Mason <clm@fb.com>, Josef Bacik <josef@toxicpanda.com>,
        David Sterba <dsterba@suse.com>, a1bert@atlas.cz
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From:   Forza <forza@tnonline.net>
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On 2023-07-06 12:54, Linux regression tracking (Thorsten Leemhuis) wrote:
> On 06.07.23 10:08, Forza wrote:
>>>> On Wed, May 24, 2023 at 11:13:57AM +0200, David Sterba wrote:
>> [...]
>> A small update.
> 
> Thx for this.
> 
>> I have been able test 6.2.16, all 6.3.x and 6.4.1 and they all show
>> the same issue.
>>
>> I am now trying 6.1.37 since two days and have not been able to
>> reproduce this issue on any of my virtual qemu/kvm machines. Perhaps
>> this information is helpful in finding the root cause?
> 
> That means it's most likely a regression between v6.1..v6.2 (or
> v6.1..v6.2.16 if we are unlucky) somewhere (from earlier in the thread
> it sounds like it might not be Btrfs).

Agreed, I do not think this specific bug (cpuidle /  default_enter_idle 
leaked IRQ state) is Btrfs related. Some of the virtual machines I test 
on do not use Btrfs.
> 
> Which makes we wonder: how long do you usually need to reproduce the
> issue? If it's not too long it might mean that a bisection is the best
> way forward, unless some developer sits down and looks closely at the
> logs. With a bit of luck some dev will do that; but if we are unlucky we
> likely will need a bisection.
> 

It has varied. Sometimes immediately upon boot, but can take several 
hours or a day before showing up.


Also, I forgot to say I was basing my kernels on gentoo-kernels, which 
has some patches against vanilla. Therefore I will I will compile a set 
of vanilla kernels from 6.1.37 until 6.4.2 and run them in my testing 
machines to see where the problem is happening.

This is not a fast system, so it will likely take several days. But I 
will keep you posted.

Meanwhile, if you think of any specific kernel debug options, tracing, 
etc, that I should enable, let me know

Should we change the Subject line of this email thread?

Thanks

~Forza

> 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
> If I did something stupid, please tell me, as explained on that page.
>