mm/page_alloc: check high-order pages for corruption during PCP operations

Eric Dumazet pointed out that commit 44042b449872 ("mm/page_alloc: allow
high-order pages to be stored on the per-cpu lists") only checks the
head page during PCP refill and allocation operations.  This was an
oversight and all pages should be checked.  This will incur a small
performance penalty but it's necessary for correctness.

Link: https://lkml.kernel.org/r/20220310092456.GJ15701@techsingularity.net
Fixes: 44042b449872 ("mm/page_alloc: allow high-order pages to be stored on the per-cpu lists")
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reported-by: Eric Dumazet <edumazet@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Wei Xu <weixugc@google.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 5d126853e239c47e3af75c0c18d11188e285ef53..e36d7631a64c191dd9131c1d47b80d062e21bd4a 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2291,23 +2291,36 @@ static inline int check_new_page(struct page *page)
        return 1;
 }
 
+static bool check_new_pages(struct page *page, unsigned int order)
+{
+       int i;
+       for (i = 0; i < (1 << order); i++) {
+               struct page *p = page + i;
+
+               if (unlikely(check_new_page(p)))
+                       return true;
+       }
+
+       return false;
+}
+
 #ifdef CONFIG_DEBUG_VM
 /*
  * With DEBUG_VM enabled, order-0 pages are checked for expected state when
  * being allocated from pcp lists. With debug_pagealloc also enabled, they are
  * also checked when pcp lists are refilled from the free lists.
  */
-static inline bool check_pcp_refill(struct page *page)
+static inline bool check_pcp_refill(struct page *page, unsigned int order)
 {
        if (debug_pagealloc_enabled_static())
-               return check_new_page(page);
+               return check_new_pages(page, order);
        else
                return false;
 }
 
-static inline bool check_new_pcp(struct page *page)
+static inline bool check_new_pcp(struct page *page, unsigned int order)
 {
-       return check_new_page(page);
+       return check_new_pages(page, order);
 }
 #else
 /*
@@ -2315,32 +2328,19 @@ static inline bool check_new_pcp(struct page *page)
  * when pcp lists are being refilled from the free lists. With debug_pagealloc
  * enabled, they are also checked when being allocated from the pcp lists.
  */
-static inline bool check_pcp_refill(struct page *page)
+static inline bool check_pcp_refill(struct page *page, unsigned int order)
 {
-       return check_new_page(page);
+       return check_new_pages(page, order);
 }
-static inline bool check_new_pcp(struct page *page)
+static inline bool check_new_pcp(struct page *page, unsigned int order)
 {
        if (debug_pagealloc_enabled_static())
-               return check_new_page(page);
+               return check_new_pages(page, order);
        else
                return false;
 }
 #endif /* CONFIG_DEBUG_VM */
 
-static bool check_new_pages(struct page *page, unsigned int order)
-{
-       int i;
-       for (i = 0; i < (1 << order); i++) {
-               struct page *p = page + i;
-
-               if (unlikely(check_new_page(p)))
-                       return true;
-       }
-
-       return false;
-}
-
 inline void post_alloc_hook(struct page *page, unsigned int order,
                                gfp_t gfp_flags)
 {
@@ -2982,7 +2982,7 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order,
                if (unlikely(page == NULL))
                        break;
 
-               if (unlikely(check_pcp_refill(page)))
+               if (unlikely(check_pcp_refill(page, order)))
                        continue;
 
                /*
@@ -3600,7 +3600,7 @@ struct page *__rmqueue_pcplist(struct zone *zone, unsigned int order,
                page = list_first_entry(list, struct page, lru);
                list_del(&page->lru);
                pcp->count -= 1 << order;
-       } while (check_new_pcp(page));
+       } while (check_new_pcp(page, order));
 
        return page;
 }