Fix 5.7-rc6-mm1 page migration crash in unmap_and_move(): when the page to be migrated has been freed from under us, that is considered a MIGRATEPAGE_SUCCESS, but no newpage has been allocated (and I don't think it would ever need to be counted as a successful THP migration).
Signed-off-by: Hugh Dickins <[email protected]> --- Fix to mm-vmstat-add-events-for-pmd-based-thp-migration-without-split.patch mm/migrate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- 5.7-rc6-mm1/mm/migrate.c 2020-05-20 12:21:56.117693827 -0700 +++ linux/mm/migrate.c 2020-05-20 15:08:12.319476978 -0700 @@ -1248,7 +1248,7 @@ out: * we want to retry. */ if (rc == MIGRATEPAGE_SUCCESS) { - if (PageTransHuge(newpage)) + if (newpage && PageTransHuge(newpage)) thp_migration_success(true); put_page(page); if (reason == MR_MEMORY_FAILURE) {
