ACK: [SRU][N][PATCH 0/1] fix autopkgtest-virt-qemu regression with 6.8

[Marcelo Henrique Cerri]

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On Sun, May 12 2024, Andrea Righi wrote:
> BugLink: https://bugs.launchpad.net/bugs/2056461
>
> [Impact]
>
> It seems that kernel 6.8 introduced a regression in the 9pfs related to
> caching and netfslib, that can cause some user-space apps to read
> content from files that is not up-to-date (when they are used in a
> producer/consumer fashion).
>
> It seems that the offending commit is this one:
>
>  80105ed2fd27 ("9p: Use netfslib read/write_iter")
>
> Reverting the commit seems to fix the problem. However the actual bug
> might be in netfslib or how netfslib is used in the 9p context.
>
> The regression has been reported upstream and we are still investigating
> (https://lore.kernel.org/lkml/Zj0ErxVBE3DYT2Ea@gpd/).
>
> In the meantime it probably makes sense to temporarily revert the commit
> as a SAUCE patch. Then we will drop the SAUCE patch once we'll have a
> proper fix upstream.
>
> [Test case]
>
> The following test should complete correctly without any timeout:
>
>   pull-lp-source -d hello
>   autopkgtest-buildvm-ubuntu-cloud -r noble
>   autopkgtest -U hello*.dsc -- qemu ./autopkgtest-noble-amd64.img
>
> [Fix]
>
> Revert the following commit (until we have a proper fix upstream):
>
>  80105ed2fd27 ("9p: Use netfslib read/write_iter")
>
> [Regression potential]
>
> We may experience other regressions related to 9pfs with this change,
> however it's quite unlikely to happen since we are reverting a commit,
> restoring the previous behavior.


Acked-by: Marcelo Henrique Cerri <marcelo.cerri at canonical.com>

- --
Regards,
Marcelo
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