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authorHugh Dickins <hughd@google.com>2018-06-01 16:50:50 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-06-02 09:33:47 -0700
commit145e1a71e090575c74969e3daa8136d1e5b99fc8 (patch)
treec17c5356ad4f266fd806bd7808a5b3435433c7f1
parent2d077d4b59924acd1f5180c6fb73b57f4771fde6 (diff)
mm: fix the NULL mapping case in __isolate_lru_page()
George Boole would have noticed a slight error in 4.16 commit 69d763fc6d3a ("mm: pin address_space before dereferencing it while isolating an LRU page"). Fix it, to match both the comment above it, and the original behaviour. Although anonymous pages are not marked PageDirty at first, we have an old habit of calling SetPageDirty when a page is removed from swap cache: so there's a category of ex-swap pages that are easily migratable, but were inadvertently excluded from compaction's async migration in 4.16. Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1805302014001.12558@eggly.anvils Fixes: 69d763fc6d3a ("mm: pin address_space before dereferencing it while isolating an LRU page") Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Mel Gorman <mgorman@techsingularity.net> Reported-by: Ivan Kalvachev <ikalvachev@gmail.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/vmscan.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 9b697323a88c..9270a4370d54 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1418,7 +1418,7 @@ int __isolate_lru_page(struct page *page, isolate_mode_t mode)
return ret;
mapping = page_mapping(page);
- migrate_dirty = mapping && mapping->a_ops->migratepage;
+ migrate_dirty = !mapping || mapping->a_ops->migratepage;
unlock_page(page);
if (!migrate_dirty)
return ret;