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.
Fixes: 44042b449872 ("mm/page_alloc: allow high-order pages to be stored on the per-cpu lists")
Reported-by: Eric Dumazet <[email protected]>
Signed-off-by: Mel Gorman <[email protected]>
Acked-by: Eric Dumazet <[email protected]>
---
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 3589febc6d31..2920344fa887 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;
}
On 3/10/22 10:24, Mel Gorman wrote:
> 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.
>
> Fixes: 44042b449872 ("mm/page_alloc: allow high-order pages to be stored on the per-cpu lists")
> Reported-by: Eric Dumazet <[email protected]>
> Signed-off-by: Mel Gorman <[email protected]>
> Acked-by: Eric Dumazet <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
On Thu, Mar 10, 2022 at 09:24:56AM +0000, Mel Gorman wrote:
> 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.
> Fixes: 44042b449872 ("mm/page_alloc: allow high-order pages to be stored
> on the per-cpu lists")
> Reported-by: Eric Dumazet <[email protected]>
> Signed-off-by: Mel Gorman <[email protected]>
> Acked-by: Eric Dumazet <[email protected]>
Reviewed-by: Shakeel Butt <[email protected]>
On Thu, 10 Mar 2022, Mel Gorman wrote:
> 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.
>
> Fixes: 44042b449872 ("mm/page_alloc: allow high-order pages to be stored on the per-cpu lists")
> Reported-by: Eric Dumazet <[email protected]>
> Signed-off-by: Mel Gorman <[email protected]>
> Acked-by: Eric Dumazet <[email protected]>
Acked-by: David Rientjes <[email protected]>