Re: [PATCH 2/5] mm: limit pagecache folio refcount when splicing into pipes

[Jose A. Perez de Azpillaga]

On 11/5/26 2:10 PM, David Hildenbrand (Arm) wrote:
> Similar to mapping pagecache folios into page tables, let's reject splicing
> folios into a pipe if the refcount is at it's limit, similar to how we
> handle it during GUP.
> 
> This will prevent more cases of possible folio refcount overflows with
> large pagecache folios.
> 
> Let's keep it simple and check in the two callers of
> splice_folio_into_pipe().
> 
> Also check in try_get_page() to cover pipe-buffer duplication by tee()
> and partial pipe-to-pipe splicing.
> 
> Fixes: 800d8c63b2e9 ("shmem: add huge pages support")
> Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS")
> Fixes: 793917d997df ("mm/readahead: Add large folio readahead")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: David Hildenbrand (Arm) <david@xxxxxxxxxx>

LGTM:

Reviewed-by: Jose A. Perez de Azpillaga <azpijr@xxxxxxxxx>

-- 
cheers,
jose a. p-a