Commit d824ec2a authored by Jan Kara's avatar Jan Kara Committed by Andrew Morton
Browse files

mm: do not reclaim private data from pinned page 

If the page is pinned, there's no point in trying to reclaim it. 
Furthermore if the page is from the page cache we don't want to reclaim
fs-private data from the page because the pinning process may be writing
to the page at any time and reclaiming fs private info on a dirty page can
upset the filesystem (see link below).

Link: https://lore.kernel.org/linux-mm/20180103100430.GE4911@quack2.suse.cz
Link: https://lkml.kernel.org/r/20230428124140.30166-1-jack@suse.cz


Signed-off-by: default avatarJan Kara <jack@suse.cz>
Reviewed-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarLorenzo Stoakes <lstoakes@gmail.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarJohn Hubbard <jhubbard@nvidia.com>
Acked-by: default avatarDavid Hildenbrand <david@redhat.com>
Acked-by: default avatarPeter Xu <peterx@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent a6a491c0

mm/vmscan.c

+10 −0
Original line number Diff line number Diff line
@@ -1967,6 +1967,16 @@ static unsigned int shrink_folio_list(struct list_head *folio_list, 
			}

		}



		/*

		 * Folio is unmapped now so it cannot be newly pinned anymore.

		 * No point in trying to reclaim folio if it is pinned.

		 * Furthermore we don't want to reclaim underlying fs metadata

		 * if the folio is pinned and thus potentially modified by the

		 * pinning process as that may upset the filesystem.

		 */

		if (folio_maybe_dma_pinned(folio))

			goto activate_locked;



		mapping = folio_mapping(folio);

		if (folio_test_dirty(folio)) {

			/*