[PATCH 5.4 233/411] mm, compaction: fast_find_migrateblock() should return pfn in the target zone

Greg Kroah-Hartman
2022-06-13T11:31:04Z

From: Rei Yamamoto <yamamoto.rei@jp.fujitsu.com>

commit bbe832b9db2e1ad21522f8f0bf02775fff8a0e0e upstream.

At present, pages not in the target zone are added to cc->migratepages
list in isolate_migratepages_block(). As a result, pages may migrate
between nodes unintentionally.

This would be a serious problem for older kernels without commit
a984226f457f849e ("mm: memcontrol: remove the pgdata parameter of
mem_cgroup_page_lruvec"), because it can corrupt the lru list by
handling pages in list without holding proper lru_lock.

Avoid returning a pfn outside the target zone in the case that it is
not aligned with a pageblock boundary. Otherwise
isolate_migratepages_block() will handle pages not in the target zone.

Link: https://lkml.kernel.org/r/20220511044300.4069-1-yamamoto.rei@jp.fujitsu.com
Fixes: 70b44595eafe ("mm, compaction: use free lists to quickly locate a migration source")
Signed-off-by: Rei Yamamoto <yamamoto.rei@jp.fujitsu.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Don Dutile <ddutile@redhat.com>
Cc: Wonhyuk Yang <vvghjk1234@gmail.com>
Cc: Rei Yamamoto <yamamoto.rei@jp.fujitsu.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
mm/compaction.c | 2 ++
1 file changed, 2 insertions(+)

--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1709,6 +1709,8 @@ static unsigned long fast_find_migratebl

update_fast_start_pfn(cc, free_pfn);
pfn = pageblock_start_pfn(free_pfn);
+ if (pfn < cc->zone->zone_start_pfn)
+ pfn = cc->zone->zone_start_pfn;
cc->fast_search_fail = 0;
found_block = true;
set_pageblock_skip(freepage);