mm, compaction: fast_find_migrateblock() should return pfn in the target zone

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/[email protected]
Fixes: 70b44595eafe ("mm, compaction: use free lists to quickly locate a migration source")
Signed-off-by: Rei Yamamoto <[email protected]>
Reviewed-by: Miaohe Lin <[email protected]>
Acked-by: Mel Gorman <[email protected]>
Reviewed-by: Oscar Salvador <[email protected]>
Cc: Don Dutile <[email protected]>
Cc: Wonhyuk Yang <[email protected]>
Cc: Rei Yamamoto <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions