Re: [regression] 5.15 kernel triggering 100x more inode evictions

[Nicholas D Steeves <sten@debian.org>]

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Hi Bruno,

Thorsten Leemhuis <regressions@leemhuis.info> writes:

> On 09.04.22 19:12, Bruno Damasceno Freire wrote:
>> On 08.04.22 04:50, Thorsten Leemhuis wrote:
>>> On 08.04.22 17:55, Filipe Manana wrote:
>>>> On Fri, Apr 08, 2022 at 04:52:22PM +0200, David Sterba wrote:
>>>>> On Fri, Apr 08, 2022 at 12:32:20PM +0200, Thorsten Leemhuis wrote:
>>> Bruno, under these circumstances I'd say you need to bisect this to get
>>> us closer to the root of the problem (and a fix for it). Sadly that how
>>> it is sometimes, as briefly explained here:
>>>
>>> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/Documentation/admin-guide/reporting-regressions.rst#n140
>> 
>> Ok Thorsten.
>> 
>> It's not sad at all: I had a great time researching this regression and
>> gained a lot of knowledge while doing so. The problem is that I am just a
>> simple user at its limits here and additional bisection is probably beyond my
>> abilities.
>
> Maybe, but I think you underestimate yourself here. Give it a try, it's
> not that hard once you figured out how to build and install a vanilla
> kernel (which you did already afaics; and if not: it's not that hard and
> you learn new stuff, too) and have some test case to check if the
> problem is there or now (which you already have afaics).
>

I also think it's something you can manage :-)

Something like:

1. Use the .config from /boot/config-ubuntu_5.14.x
2. git bisect start
3. git bisect good v5.14 (7d2a07b)
4. git bisect bad v5.15 (8bb7eca)
5. Open a guide like these ones on another device, or print it out:
  https://www.metaltoad.com/blog/beginners-guide-git-bisect-process-elimination
  https://wiki.gentoo.org/wiki/Kernel_git-bisect
  https://wiki.ubuntu.com/Kernel/KernelBisection
  https://ldpreload.com/blog/git-bisect-run ("Finding a kernel
  regression in half an hour with git bisect run")
6. make oldconfig
7. make bindeb-pkg
8. Deb packages are in ../
9. Install, reboot, run tests, confirm logs, iterate

Thank you for running these tests.  By chance, would you have time to
compare 5.10.x to 5.15.x, or have you already compared them?  I'm
always the most curious about how the latest LTS kernel compares to
latest_LTS-1 ;-)

Regards,
Nicholas

P.S. I'm sure you'll be able to find someone on IRC who'd be willing to
help you, should any help be necessary!

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