mm/gup: remove unnecessary check in memfd_pin_folios()

Patch series "mm/gup: Cleanup memfd_pin_folios()".

A couple straightforward cleanups to memfd_pin_folios() found through code
inspection.  Saves 124 bytes of kernel text overall and makes the code
more readable.

This patch (of 2):

Commit 89c1905d9c14 ("mm/gup: introduce memfd_pin_folios() for pinning
memfd folios") checks if filemap_get_folios_contig() returned duplicate
folios to prevent multiple attempts at pinning the same folio.

Commit 8ab1b1602396 ("mm: fix filemap_get_folios_contig returning batches
of identical folios") ensures that filemap_get_folios_contig() returns a
batch of distinct folios.

We can remove the duplicate folio check to simplify the code and save 58
bytes of text.

Link: https://lkml.kernel.org/r/20250430010059.892632-1-vishal.moola@gmail.com
Link: https://lkml.kernel.org/r/20250430010059.892632-2-vishal.moola@gmail.com
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Vivek Kasireddy <vivek.kasireddy@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/gup.c b/mm/gup.c
index 91bbf57579f0cffdc0bf407b6f3930cfee9a6b05..e6e2a9386850952c6596ff7bf2d549330ad417f2 100644 (file)
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -3590,7 +3590,7 @@ long memfd_pin_folios(struct file *memfd, loff_t start, loff_t end,
 {
        unsigned int flags, nr_folios, nr_found;
        unsigned int i, pgshift = PAGE_SHIFT;
-       pgoff_t start_idx, end_idx, next_idx;
+       pgoff_t start_idx, end_idx;
        struct folio *folio = NULL;
        struct folio_batch fbatch;
        struct hstate *h;
@@ -3640,19 +3640,7 @@ long memfd_pin_folios(struct file *memfd, loff_t start, loff_t end,
                                folio = NULL;
                        }
 
-                       next_idx = 0;
                        for (i = 0; i < nr_found; i++) {
-                               /*
-                                * As there can be multiple entries for a
-                                * given folio in the batch returned by
-                                * filemap_get_folios_contig(), the below
-                                * check is to ensure that we pin and return a
-                                * unique set of folios between start and end.
-                                */
-                               if (next_idx &&
-                                   next_idx != folio_index(fbatch.folios[i]))
-                                       continue;
-
                                folio = page_folio(&fbatch.folios[i]->page);
 
                                if (try_grab_folio(folio, 1, FOLL_PIN)) {
@@ -3665,7 +3653,6 @@ long memfd_pin_folios(struct file *memfd, loff_t start, loff_t end,
                                        *offset = offset_in_folio(folio, start);
 
                                folios[nr_folios] = folio;
-                               next_idx = folio_next_index(folio);
                                if (++nr_folios == max_folios)
                                        break;
                        }