+ mm-migration-fix-potential-page-refcounts-leak-in-migrate_pages.patch added to -mm tree

+ mm-migration-fix-potential-page-refcounts-leak-in-migrate_pages.patch added to -mm tree

[Andrew Morton]

The patch titled
     Subject: mm/migration: fix potential page refcounts leak in migrate_pages
has been added to the -mm tree.  Its filename is
     mm-migration-fix-potential-page-refcounts-leak-in-migrate_pages.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/mm-migration-fix-potential-page-refcounts-leak-in-migrate_pages.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/mm-migration-fix-potential-page-refcounts-leak-in-migrate_pages.patch

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------------------------------------------------------
From: Miaohe Lin <linmiaohe@huawei.com>
Subject: mm/migration: fix potential page refcounts leak in migrate_pages

In -ENOMEM case, there might be some subpages of fail-to-migrate THPs left
in thp_split_pages list.  We should move them back to migration list so
that they could be put back to the right list by the caller otherwise the
page refcnt will be leaked here.  Also adjust nr_failed and nr_thp_failed
accordingly to make vm events account more accurate.

Link: https://lkml.kernel.org/r/20220318111709.60311-10-linmiaohe@huawei.com
Fixes: b5bade978e9b ("mm: migrate: fix the return value of migrate_pages()")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Alistair Popple <apopple@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/migrate.c |    8 ++++++++
 1 file changed, 8 insertions(+)

--- a/mm/migrate.c~mm-migration-fix-potential-page-refcounts-leak-in-migrate_pages
+++ a/mm/migrate.c
@@ -1434,6 +1434,14 @@ retry:
 				}
 
 				nr_failed_pages += nr_subpages;
+				/*
+				 * There might be some subpages of fail-to-migrate THPs
+				 * left in thp_split_pages list. Move them back to migration
+				 * list so that they could be put back to the right list by
+				 * the caller otherwise the page refcnt will be leaked.
+				 */
+				list_splice_init(&thp_split_pages, from);
+				nr_thp_failed += thp_retry;
 				goto out;
 			case -EAGAIN:
 				if (is_thp)
_

Patches currently in -mm which might be from linmiaohe@huawei.com are

mm-shmem-make-shmem_init-return-void.patch
mm-memcg-remove-unneeded-nr_scanned.patch
mm-mremap-use-helper-mlock_future_check.patch
mm-mlock-fix-two-bugs-in-user_shm_lock.patch
mm-compaction-use-helper-isolation_suitable.patch
mm-migration-remove-unneeded-local-variable-mapping_locked.patch
mm-migration-remove-unneeded-out-label.patch
mm-migration-remove-unneeded-local-variable-page_lru.patch
mm-migration-fix-the-confusing-pagetranshuge-check.patch
mm-migration-use-helper-function-vma_lookup-in-add_page_for_migration.patch
mm-migration-use-helper-macro-min-in-do_pages_stat.patch
mm-migration-avoid-unneeded-nodemask_t-initialization.patch
mm-migration-remove-some-duplicated-codes-in-migrate_pages.patch
mm-migration-fix-potential-page-refcounts-leak-in-migrate_pages.patch
mm-migration-fix-potential-invalid-node-access-for-reclaim-based-migration.patch
mm-migration-fix-possible-do_pages_stat_array-racing-with-memory-offline.patch