Add support for the new vm_uffd_ops API for shmem. Note that this only introduces the support, the API is not yet used by core mm. It only needs a separate uffd_get_folio() definition but that's oneliner. Due to the limitation of the current vm_uffd_ops on MISSING mode support, the shmem UFFDIO_COPY/ZEROPAGE process are still hard-coded in mm/. Cc: Hugh Dickins Acked-by: Mike Rapoport Signed-off-by: Peter Xu --- mm/shmem.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/mm/shmem.c b/mm/shmem.c index 4855eee227310..e7b44efbfddf2 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -3148,6 +3148,13 @@ static inline struct inode *shmem_get_inode(struct mnt_idmap *idmap, #endif /* CONFIG_TMPFS_QUOTA */ #ifdef CONFIG_USERFAULTFD + +static int shmem_uffd_get_folio(struct inode *inode, pgoff_t pgoff, + struct folio **folio) +{ + return shmem_get_folio(inode, pgoff, 0, folio, SGP_NOALLOC); +} + int shmem_mfill_atomic_pte(pmd_t *dst_pmd, struct vm_area_struct *dst_vma, unsigned long dst_addr, @@ -5191,6 +5198,18 @@ static int shmem_error_remove_folio(struct address_space *mapping, return 0; } +#ifdef CONFIG_USERFAULTFD +static const struct vm_uffd_ops shmem_uffd_ops = { + .uffd_features = __VM_UFFD_FLAGS, + .uffd_ioctls = BIT(_UFFDIO_COPY) | + BIT(_UFFDIO_ZEROPAGE) | + BIT(_UFFDIO_WRITEPROTECT) | + BIT(_UFFDIO_CONTINUE) | + BIT(_UFFDIO_POISON), + .uffd_get_folio = shmem_uffd_get_folio, +}; +#endif + static const struct address_space_operations shmem_aops = { .dirty_folio = noop_dirty_folio, #ifdef CONFIG_TMPFS @@ -5293,6 +5312,9 @@ static const struct vm_operations_struct shmem_vm_ops = { .set_policy = shmem_set_policy, .get_policy = shmem_get_policy, #endif +#ifdef CONFIG_USERFAULTFD + .userfaultfd_ops = &shmem_uffd_ops, +#endif }; static const struct vm_operations_struct shmem_anon_vm_ops = { @@ -5302,6 +5324,9 @@ static const struct vm_operations_struct shmem_anon_vm_ops = { .set_policy = shmem_set_policy, .get_policy = shmem_get_policy, #endif +#ifdef CONFIG_USERFAULTFD + .userfaultfd_ops = &shmem_uffd_ops, +#endif }; int shmem_init_fs_context(struct fs_context *fc) -- 2.50.1