On 6/24/2022 10:53 AM, Huang Ying wrote:
In unmap_and_move(), if the new THP cannot be allocated, -ENOMEM will
be returned, and migrate_pages() will try to split the THP unless
"reason" is MR_NUMA_MISPLACED (that is, nosplit == true). But when
nosplit == true, the THP migration failure will not be counted. This
is incorrect. So in this patch, the THP migration failure will be
counted for -ENOMEM regardless of nosplit is true or false. The
nr_failed counting is fixed too, although that is not used actually.
No strong opinion about the 'nr_failed' updating, like you said, we did
not use it in this case. Maybe just add some comments instead of adding
some unused code? Otherwise looks good to me.
Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
Fixes: 5984fabb6e82 ("mm: move_pages: report the number of non-attempted pages")
Cc: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
--- > mm/migrate.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index 82444e7df9f1..542533e4e3cf 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1425,11 +1425,11 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
/*
* When memory is low, don't bother to try to migrate
* other pages, just exit.
- * THP NUMA faulting doesn't split THP to retry.
*/
- if (is_thp && !nosplit) {
+ if (is_thp) {
nr_thp_failed++;
- if (!try_split_thp(page, &thp_split_pages)) {
+ /* THP NUMA faulting doesn't split THP to retry. */
+ if (!nosplit && !try_split_thp(page, &thp_split_pages)) {
nr_thp_split++;
goto retry;
}
@@ -1446,6 +1446,8 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
*/
list_splice_init(&thp_split_pages, from);
nr_thp_failed += thp_retry;
+ if (!no_subpage_counting)
+ nr_failed += retry;
goto out;
case -EAGAIN:
if (is_thp)
