The patch titled Subject: mm: migrate: fix return value if all subpages of THPs are migrated successfully has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-migrate-fix-return-value-if-all-subpages-of-thps-are-migrated-successfully.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: Baolin Wang baolin.wang@linux.alibaba.com Subject: mm: migrate: fix return value if all subpages of THPs are migrated successfully Date: Mon, 24 Oct 2022 16:34:21 +0800

During THP migration, if THPs are not migrated but they are split and all subpages are migrated successfully, migrate_pages() will still return the number of THP pages that were not migrated. This will confuse the callers of migrate_pages(). For example, the longterm pinning will failed though all pages are migrated successfully.

Thus we should return 0 to indicate that all pages are migrated in this case

Link: https://lkml.kernel.org/r/de386aa864be9158d2f3b344091419ea7c38b2f7.166659984... Fixes: b5bade978e9b ("mm: migrate: fix the return value of migrate_pages()") Signed-off-by: Baolin Wang baolin.wang@linux.alibaba.com Reviewed-by: Alistair Popple apopple@nvidia.com Reviewed-by: Yang Shi shy828301@gmail.com Cc: David Hildenbrand david@redhat.com Cc: "Huang, Ying" ying.huang@intel.com Cc: Zi Yan ziy@nvidia.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/migrate.c | 7 +++++++ 1 file changed, 7 insertions(+)

--- a/mm/migrate.c~mm-migrate-fix-return-value-if-all-subpages-of-thps-are-migrated-successfully +++ a/mm/migrate.c @@ -1582,6 +1582,13 @@ out: */ list_splice(&ret_pages, from);

+ /* + * Return 0 in case all subpages of fail-to-migrate THPs are + * migrated successfully. + */ + if (list_empty(from)) + rc = 0; + count_vm_events(PGMIGRATE_SUCCESS, nr_succeeded); count_vm_events(PGMIGRATE_FAIL, nr_failed_pages); count_vm_events(THP_MIGRATION_SUCCESS, nr_thp_succeeded); _

Patches currently in -mm which might be from baolin.wang@linux.alibaba.com are

mm-migrate-fix-return-value-if-all-subpages-of-thps-are-migrated-successfully.patch mm-migrate-try-again-if-thp-split-is-failed-due-to-page-refcnt.patch