mm: page_alloc: move free pages when converting block during isolation

When claiming a block during compaction isolation, move any remaining free
pages to the correct freelists as well, instead of stranding them on the
wrong list.  Otherwise, this encourages incompatible page mixing down the
line, and thus long-term fragmentation.

Link: https://lkml.kernel.org/r/20240320180429.678181-5-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Tested-by: "Huang, Ying" <ying.huang@intel.com>
Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 2c03336def76f0b143687e96bf0180909ac55d20..dcacb86efd29854eef70acbf755aaf2fa460ac94 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2653,9 +2653,12 @@ int __isolate_free_page(struct page *page, unsigned int order)
                         * Only change normal pageblocks (i.e., they can merge
                         * with others)
                         */
-                       if (migratetype_is_mergeable(mt))
+                       if (migratetype_is_mergeable(mt)) {
                                set_pageblock_migratetype(page,
                                                          MIGRATE_MOVABLE);
+                               move_freepages_block(zone, page,
+                                                    MIGRATE_MOVABLE, NULL);
+                       }
                }
        }