Re: [PATCH v2 2/5] userfaultfd, shmem: use a VMA callback to handle UFFDIO_CONTINUE

On 11/25/25 19:38, Mike Rapoport wrote:

From: "Mike Rapoport (Microsoft)" rppt@kernel.org

When userspace resolves a page fault in a shmem VMA with UFFDIO_CONTINUE it needs to get a folio that already exists in the pagecache backing that VMA.

Instead of using shmem_get_folio() for that, add a get_folio() method to 'struct vm_operations_struct' that will return a folio if it exists in the VMA's pagecache at given pgoff.

Implement get_folio() method for shmem and slightly refactor userfaultfd's mfill_atomic() and mfill_atomic_pte_continue() to support this new API.

Signed-off-by: Mike Rapoport (Microsoft) rppt@kernel.org

Acked-by: David Hildenbrand (Red Hat) david@kernel.org