mm: wrap __find_buddy_pfn() with a necessary buddy page validation
Whenever the buddy of a page is found from __find_buddy_pfn(),
page_is_buddy() should be used to check its validity. Add a helper
function find_buddy_page_pfn() to find the buddy page and do the check
together.
[ziy@nvidia.com: updates per David]
Link: https://lkml.kernel.org/r/20220401230804.1658207-2-zi.yan@sent.com
Link: https://lore.kernel.org/linux-mm/CAHk-=wji_AmYygZMTsPMdJ7XksMt7kOur8oDfDdniBRMjm4VkQ@mail.gmail.com/
Link: https://lkml.kernel.org/r/7236E7CA-B5F1-4C04-AB85-E86FA3E9A54B@nvidia.com
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Zi Yan <ziy@nvidia.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index f67c4c7..ff0ea63 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -70,7 +70,6 @@ static void unset_migratetype_isolate(struct page *page, unsigned migratetype)
unsigned long flags, nr_pages;
bool isolated_page = false;
unsigned int order;
- unsigned long pfn, buddy_pfn;
struct page *buddy;
zone = page_zone(page);
@@ -89,11 +88,9 @@ static void unset_migratetype_isolate(struct page *page, unsigned migratetype)
if (PageBuddy(page)) {
order = buddy_order(page);
if (order >= pageblock_order && order < MAX_ORDER - 1) {
- pfn = page_to_pfn(page);
- buddy_pfn = __find_buddy_pfn(pfn, order);
- buddy = page + (buddy_pfn - pfn);
-
- if (!is_migrate_isolate_page(buddy)) {
+ buddy = find_buddy_page_pfn(page, page_to_pfn(page),
+ order, NULL);
+ if (buddy && !is_migrate_isolate_page(buddy)) {
isolated_page = !!__isolate_free_page(page, order);
/*
* Isolating a free page in an isolated pageblock
