Commit 30f62b92 authored by Vishal Moola (Oracle)'s avatar Vishal Moola (Oracle) Committed by Andrew Morton
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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 89c1905d ("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 8ab1b160 ("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: default avatarVishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: default avatarDavid Hildenbrand <david@redhat.com>
Cc: Vivek Kasireddy <vivek.kasireddy@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent dd309bfc

mm/gup.c

+1 −14
Original line number Diff line number Diff line
@@ -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;

			}