The quilt patch titled Subject: mm/migrate: putback split folios when numa hint migration fails has been removed from the -mm tree. Its filename was mm-migrate-putback-split-folios-when-numa-hint-migration-fails.patch

This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------ From: Peter Xu peterx@redhat.com Subject: mm/migrate: putback split folios when numa hint migration fails Date: Mon, 8 Jul 2024 17:55:37 -0400

This issue is not from any report yet, but by code observation only.

This is yet another fix besides Hugh's patch [1] but on relevant code path, where eager split of folio can happen if the folio is already on deferred list during a folio migration.

Here the issue is NUMA path (migrate_misplaced_folio()) may start to encounter such folio split now even with MR_NUMA_MISPLACED hint applied. Then when migrate_pages() didn't migrate all the folios, it's possible the split small folios be put onto the list instead of the original folio. Then putting back only the head page won't be enough.

Fix it by putting back all the folios on the list.

[1] https://lore.kernel.org/all/46c948b4-4dd8-6e03-4c7b-ce4e81cfa536@google.com/

[akpm@linux-foundation.org: remove now unused local `nr_pages'] Link: https://lkml.kernel.org/r/20240708215537.2630610-1-peterx@redhat.com Fixes: 7262f208ca68 ("mm/migrate: split source folio if it is on deferred split list") Signed-off-by: Peter Xu peterx@redhat.com Reviewed-by: Zi Yan ziy@nvidia.com Reviewed-by: Baolin Wang baolin.wang@linux.alibaba.com Cc: Yang Shi shy828301@gmail.com Cc: Hugh Dickins hughd@google.com Cc: Huang Ying ying.huang@intel.com Cc: David Hildenbrand david@redhat.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/migrate.c | 11 ++--------- 1 file changed, 2 insertions(+), 9 deletions(-)

--- a/mm/migrate.c~mm-migrate-putback-split-folios-when-numa-hint-migration-fails +++ a/mm/migrate.c @@ -2621,20 +2621,13 @@ int migrate_misplaced_folio(struct folio int nr_remaining; unsigned int nr_succeeded; LIST_HEAD(migratepages); - int nr_pages = folio_nr_pages(folio);

list_add(&folio->lru, &migratepages); nr_remaining = migrate_pages(&migratepages, alloc_misplaced_dst_folio, NULL, node, MIGRATE_ASYNC, MR_NUMA_MISPLACED, &nr_succeeded); - if (nr_remaining) { - if (!list_empty(&migratepages)) { - list_del(&folio->lru); - node_stat_mod_folio(folio, NR_ISOLATED_ANON + - folio_is_file_lru(folio), -nr_pages); - folio_putback_lru(folio); - } - } + if (nr_remaining && !list_empty(&migratepages)) + putback_movable_pages(&migratepages); if (nr_succeeded) { count_vm_numa_events(NUMA_PAGE_MIGRATE, nr_succeeded); if (!node_is_toptier(folio_nid(folio)) && node_is_toptier(node)) _

Patches currently in -mm which might be from peterx@redhat.com are