Since commit a49bd4d71637 ("mm, numa: rework do_pages_move"),
the semantic of move_pages() was changed to return the number of
non-migrated pages (failed to migration) and the call would be aborted
immediately if migrate_pages() returns positive value. But it didn't
report the number of pages that we even haven't attempted to migrate.
So, fix it by including non-attempted pages in the return value.
Fixes: a49bd4d71637 ("mm, numa: rework do_pages_move")
Suggested-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Wei Yang <richardw.yang@xxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [4.17+]
Signed-off-by: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
---
v2: Rebased on top of the latest mainline kernel per Andrew
mm/migrate.c | 24 ++++++++++++++++++++++--
1 file changed, 22 insertions(+), 2 deletions(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index 86873b6..9b8eb5d 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1627,8 +1627,18 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
start = i;
} else if (node != current_node) {
err = do_move_pages_to_node(mm, &pagelist, current_node);
- if (err)
+ if (err) {
+ /*
+ * Positive err means the number of failed
+ * pages to migrate. Since we are going to
+ * abort and return the number of non-migrated
+ * pages, so need incude the rest of the
+ * nr_pages that have not attempted as well.
+ */
+ if (err > 0)
+ err += nr_pages - i - 1;
goto out;
+ }
err = store_status(status, start, current_node, i - start);
if (err)
goto out;
@@ -1659,8 +1669,11 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
goto out_flush;
err = do_move_pages_to_node(mm, &pagelist, current_node);
- if (err)
+ if (err) {
+ if (err > 0)
+ err += nr_pages - i - 1;
goto out;
+ }
if (i > start) {
err = store_status(status, start, current_node, i - start);
if (err)
@@ -1674,6 +1687,13 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
/* Make sure we do not overwrite the existing error */
err1 = do_move_pages_to_node(mm, &pagelist, current_node);
+ /*
+ * Don't have to report non-attempted pages here since:
+ * - If the above loop is done gracefully there is not non-attempted
+ * page.
+ * - If the above loop is aborted to it means more fatal error
+ * happened, should return err.
+ */
if (!err1)
err1 = store_status(status, start, current_node, i - start);
if (!err)
--
1.8.3.1
