Re: (subset) [PATCH v3 0/9] mm: limit pagecache folio refcount

From: David Hildenbrand

Date: Thu Nov 12 2026 - 04:50:51 EST


On Tue, 10 Nov 2026 21:35:40 +0100, David Hildenbrand (Arm) wrote:
> Note: I really would prefer doing something else right now, but this is
> rather urgent.
>
> Users can create a lot of folio references to pagecache folios, making
> it possible to overflow the refcount of large folios.
>
> While we knew that one could in theory overflow a folio's refcount, we
> mostly assumed that bad things would happen and it wouldn't go
> unnoticed.
>
> [...]

Applied, thanks!

tree: mm/core.git
branch: for-next-fixes

Applied patches will appear soon in mm-next, followed by linux-next.

Please report any outstanding bugs that were missed during review, so we
can either drop the patch series or decide how to fix it up.

It is encouraged to provide Acked-bys, Reviewed-bys, and Tested-bys even
though the patches have already been applied. If possible, patch trailers
will be updated.

Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. Further, this is not a guarantee that the
patches will go upstream. If in doubt, please check the listed branch.

[1/9] mm: limit pagecache folio refcount when mapping pages
https://git.kernel.org/mm/core/c/61351dc9
[2/9] mm: limit pagecache folio refcount when splicing into pipes
https://git.kernel.org/mm/core/c/0ff9a420
[3/9] mm/mmu_gather: flush pending references early before the folio limit
https://git.kernel.org/mm/core/c/bfbf74ba
[4/9] iommufd: fix cleanup when adding memfd folio pins fails
https://git.kernel.org/mm/core/c/6d0d782f
[5/9] mm/gup: limit pagecache folio refcount when grabbing references
https://git.kernel.org/mm/core/c/6d3ff38d

--
Cheers,

David