From: Zi Yan <ziy@xxxxxxxxxx> I am adding support for >0 folio compaction and find the VM_BUG_ON(!list_empty(&cc->migratepages)) in compact_zone() can be triggered when a large folio is tried to be migrated, split, and its split base pages are not migrated. The fix is in patch 1. In the upstream tree, large folios can be migrated via move_pages() syscall and there is no VM_BUG_ON in do_move_pages_to_node() but pages left in the source page list will not be returned to LRU lists. This is from my code inspection and I have not reproduced it on upstream tree yet. In addition, I wonder if we need to add any large folio migration stats in addition to existing THP migration stats, at least for large folio split stats. Otherwise, large folio migrations seem to happen without any notice. Thanks. Zi Yan (1): mm/migrate: correct nr_failed in migrate_pages_sync() mm/migrate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) -- 2.42.0
