The patch below does not apply to the 6.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.10.y git checkout FETCH_HEAD git cherry-pick -x 6e49019db5f7a09a9c0e8ac4d108e656c3f8e583 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024072937-aloe-fog-7fc4@gregkh' --subject-prefix 'PATCH 6.10.y' HEAD^..
Possible dependencies:
6e49019db5f7 ("mm/migrate: putback split folios when numa hint migration fails") ee86814b0562 ("mm/migrate: move NUMA hinting fault folio isolation + checks under PTL") 4b88c23ab8c9 ("mm/migrate: make migrate_misplaced_folio() return 0 on success")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 6e49019db5f7a09a9c0e8ac4d108e656c3f8e583 Mon Sep 17 00:00:00 2001 From: Peter Xu peterx@redhat.com Date: Mon, 8 Jul 2024 17:55:37 -0400 Subject: [PATCH] mm/migrate: putback split folios when numa hint migration fails
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
diff --git a/mm/migrate.c b/mm/migrate.c index 6eb9df239230..bdbb5bb04c91 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -2621,20 +2621,13 @@ int migrate_misplaced_folio(struct folio *folio, struct vm_area_struct *vma, 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))