Commit 145e1a71 authored Jun 01, 2018 by Hugh Dickins Committed by Linus Torvalds Jun 02, 2018

mm: fix the NULL mapping case in __isolate_lru_page()

George Boole would have noticed a slight error in 4.16 commit
69d763fc ("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: 69d763fc ("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>

parent 2d077d4b

mm/vmscan.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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;

Admin message