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authorJan Kara <jack@suse.cz>2023-04-28 14:41:40 +0200
committerAndrew Morton <akpm@linux-foundation.org>2023-05-06 10:10:07 -0700
commitd824ec2a154677f63c56cc71ffe4578274f6e32e (patch)
tree931286f4be4f1cfa5bc155e906a00427d5ec8cd7
parenta6a491c048882e7e424d407d32cba0b52d9ef2bf (diff)
downloadlwn-d824ec2a154677f63c56cc71ffe4578274f6e32e.tar.gz
lwn-d824ec2a154677f63c56cc71ffe4578274f6e32e.zip
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: 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>
-rw-r--r--mm/vmscan.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 5bde07409303..d257916f39e5 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -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)) {
/*