From: Jan Kara Date: Fri, 28 Apr 2023 12:41:40 +0000 (+0200) Subject: mm: do not reclaim private data from pinned page X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=d824ec2a154677f63c56cc71ffe4578274f6e32e;p=linux.git 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 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 --- diff --git a/mm/vmscan.c b/mm/vmscan.c index 5bde074093033..d257916f39e50 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)) { /*