When freeing "tail" pages of a non-compount high-order page, we properly
subtract the allocation tag counters, however later when these pages are
released, alloc_tag_sub() will issue warnings because tags for these pages
are NULL.
This issue was originally anticipated by Vlastimil in his review [1] and
then recently reported by David.
Prevent warnings by marking the tags empty.
[1] https://lore.kernel.org/all/6db0f0c8-81cb-4d04-9560-ba73d63db4b8@suse.cz/
Suggested-by: David Wang <00107082@163.com>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
---
mm/page_alloc.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index f54c5ee1e318..2bfab96c207f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5240,9 +5240,16 @@ static void ___free_pages(struct page *page, unsigned int order,
__free_frozen_pages(page, order, fpi_flags);
else if (!head) {
pgalloc_tag_sub_pages(tag, (1 << order) - 1);
- while (order-- > 0)
+ while (order-- > 0) {
+ /*
+ * The "tail" pages of this non-compound high-order
+ * page will have no code tags, so to avoid warnings
+ * mark them as empty.
+ */
+ clear_page_tag_ref(page + (1 << order));
__free_frozen_pages(page + (1 << order), order,
fpi_flags);
+ }
}
}
--
2.51.0.384.g4c02a37b29-goog