On Tue, 7 Mar 2023, Christoph Hellwig wrote:
> Use the very low level filemap_get_entry helper to look up the
> entry in the xarray, and then:
>
> - don't bother locking the folio if only doing a userfault notification
> - open code locking the page and checking for truncation in a related
> code block
>
> This will allow to eventually remove the FGP_ENTRY flag.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Acked-by: Hugh Dickins <hughd@xxxxxxxxxx>
but Andrew, please fold in this small improvement to its comment:
[PATCH] shmem: open code the page cache lookup in shmem_get_folio_gfp fix
Adjust the new comment line: shmem folio may have been swapped out.
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
---
mm/shmem.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1905,7 +1905,7 @@ static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
if (folio) {
folio_lock(folio);
- /* Has the page been truncated? */
+ /* Has the folio been truncated or swapped out? */
if (unlikely(folio->mapping != mapping)) {
folio_unlock(folio);
folio_put(folio);
