[PATCH AUTOSEL 08/14] mm/page_alloc: check high-order pages for corruption during PCP operations

Greg Kroah-Hartman
2022-04-28T15:43:22Z

From: Mel Gorman <mgorman@techsingularity.net>

commit 77fe7f136a7312954b1b8b7eeb4bc91fc3c14a3f upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
mm/page_alloc.c | 46 +++++++++++++++++++++++-----------------------
1 file changed, 23 insertions(+), 23 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b2ef0e75fd29..adceee44adf6 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2342,23 +2342,36 @@ 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
/*
@@ -2366,32 +2379,19 @@ 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)
{
@@ -3037,7 +3037,7 @@ 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;

/*
@@ -3641,7 +3641,7 @@ 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;
}
--
2.36.0