]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commitdiff
mm: do not reclaim private data from pinned page
authorJan Kara <jack@suse.cz>
Fri, 28 Apr 2023 12:41:40 +0000 (14:41 +0200)
committerAndrew Morton <akpm@linux-foundation.org>
Sat, 6 May 2023 17:10:07 +0000 (10:10 -0700)
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: Jan Kara <jack@suse.cz>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Lorenzo Stoakes <lstoakes@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm/vmscan.c

index 5bde0740930335319afed277d16c52b2325403eb..d257916f39e50027dc7c06aa38c19430ee9dc4ee 100644 (file)
@@ -1967,6 +1967,16 @@ retry:
                        }
                }
 
+               /*
+                * 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)) {
                        /*