[OpenAFS] AFS-Cache hickups with Ubuntu and Kernel 6.17

[Cheyenne Wills]

I was able to reproduce the problem and will continue to investigate
further.

-- 
Cheyenne Wills
cwills@sinenomine.net



On Mon, 9 Mar 2026 14:29:29 +0100
Gaja Sophie Peters <gaja.peters@math.uni-hamburg.de> wrote:
> TLDR: OpenAFS on Ubuntu with kernel 6.17 is in certain circumstances
> not updating the Cache on file-deletion or file-creation happening on
> a different machine, the only fix is: echo 3 >/proc/sys/vm/drop_caches
> 
> 
> Long version: We discovered a problem with the recent advent of the 
> kernel 6.17 as the newest "hardware enablement kernel" in Ubuntu
> 24.04. Basically the existence or non-existence of a file is not
> correctly reflected by the AFS-Cache, when a file is deleted or
> created on another machine after the file was seen (or not) on the
> current machine.
> 
> ### first test: file deletion not propagated
>      #this command on a different machine# echo X >test-afs
>      $ cat test-afs
>      X
>      #this command on the other machine# rm test-afs
>      $ cat test-afs
>      X
>      $ fs flushall
>      $ cat test-afs
>      cat: test-afs: Input/output error
>      #as root# echo 3 >/proc/sys/vm/drop_caches
>      $ cat test-afs
>      cat: test-afs: No such file or directory
> ### second test: file creation not propagated
>      #this command on a different machine# echo Y >test-afs
>      $ cat test-afs
>      cat: test-afs: No such file or directory
>      $ fs flushall
>      $ cat test-afs
>      cat: test-afs: No such file or directory
>      #as root# echo 3 >/proc/sys/vm/drop_caches
>      $ cat test-afs
>      Y
> 
> We haven't yet tried to pinpoint at which exact kernel-version that 
> problem got introduced, but the Ubuntu-kernels 6.8 and 6.14 are 
> unaffected, the Ubuntu-kernel 6.17 is affected (kAFS on 6.17 is 
> unaffected). It doesn't make a difference, if the OpenAFS-version is 
> 1.8.14 with the Ubuntu-patches for Kernel 6.17 or if it is OpenAFS
> 1.8.15
> 
> The file server hosting the volume was originally 1.8.13.2-1 from
> Debian Trixie, but updating to 1.8.15 does not change anything,
> either.
> 
> Is this known? Any idea how to deal with it?
> 
> Greetings,
> Gaja Peters
> 
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