From 8d67449f907eb4297ee2f62835b1ce91f8d25488 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Fri, 28 Apr 2023 14:41:40 +0200 Subject: [PATCH] mm: do not reclaim private data from pinned page commit d824ec2a154677f63c56cc71ffe4578274f6e32e upstream. 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 Reviewed-by: Matthew Wilcox (Oracle) Reviewed-by: Lorenzo Stoakes Reviewed-by: Christoph Hellwig Reviewed-by: John Hubbard Acked-by: David Hildenbrand Acked-by: Peter Xu Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- mm/vmscan.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/mm/vmscan.c b/mm/vmscan.c index dc66f67..d1829610 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1887,6 +1887,16 @@ 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)) { /* -- 2.7.4