Commit 1412ecb3 authored by Zi Yan's avatar Zi Yan Committed by Andrew Morton
Browse files

mm/huge_memory: check new folio order when split a folio 

A folio can only be split into lower orders.

Since there are no new_order checks in debugfs, any new_order can be
passed via debugfs into split_huge_page_to_list_to_order().

Check new_order to make sure it is smaller than input folio order.

Link: https://lkml.kernel.org/r/20240307181854.138928-1-zi.yan@sent.com


Fixes: c010d47f ("mm: thp: split huge page to any lower order pages")
Signed-off-by: default avatarZi Yan <ziy@nvidia.com>
Reported-by: default avatarDan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/linux-mm/7dda9283-b437-4cf8-ab0d-83c330deb9c0@moroto.mountain/


Cc: David Hildenbrand <david@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent d221dd5f

mm/huge_memory.c

+3 −0
Original line number Diff line number Diff line
@@ -3052,6 +3052,9 @@ int split_huge_page_to_list_to_order(struct page *page, struct list_head *list, 
	VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);

	VM_BUG_ON_FOLIO(!folio_test_large(folio), folio);



	if (new_order >= folio_order(folio))

		return -EINVAL;



	/* Cannot split anonymous THP to order-1 */

	if (new_order == 1 && folio_test_anon(folio)) {

		VM_WARN_ONCE(1, "Cannot split to order-1 folio");