Re: [PATCH v3 05/16] fs: afs: correctly drop reference count on mapping failure

Lorenzo Stoakes (Oracle)
2026-03-20T19:01:15Z

On Fri, Mar 20, 2026 at 07:57:29PM +0100, Vlastimil Babka (SUSE) wrote:
> On 3/19/26 19:23, Lorenzo Stoakes (Oracle) wrote:
> > Commit 9d5403b1036c ("fs: convert most other generic_file_*mmap() users to
> > .mmap_prepare()") updated AFS to use the mmap_prepare callback in favour
> > of the deprecated mmap callback.
> >
> > However, it did not account for the fact that mmap_prepare is called
> > pre-merge, and may then be merged, nor that mmap_prepare can fail to map
> > due to an out of memory error.
>
> So that means a file can become pinned forever? OOM is probably only a
> problem with fault injection in practice, but the merge case can happen. And
> 9d5403b1036c is pre-6.18 LTS. Are we going to need Fixes: and Cc: stable then?

That'd require backporting all of the .mapped functionality and half of this
series, I don't think that's really practical.

I guess I can do a manual backport of a partial revert.

Thanks, Lorenzo