linux-kernel - [PATCH 1/6] mm/page_alloc: Fetch the correct pcp buddy during bulk free

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Date:   Thu, 17 Feb 2022 00:22:22 +0000
From:   Mel Gorman <mgorman@...hsingularity.net>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Aaron Lu <aaron.lu@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Michal Hocko <mhocko@...nel.org>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux-MM <linux-mm@...ck.org>,
        Mel Gorman <mgorman@...hsingularity.net>
Subject: [PATCH 1/6] mm/page_alloc: Fetch the correct pcp buddy during bulk free

free_pcppages_bulk() prefetches buddies about to be freed but the
order must also be passed in as PCP lists store multiple orders.

Fixes: 44042b449872 ("mm/page_alloc: allow high-order pages to be stored on the per-cpu lists")
Signed-off-by: Mel Gorman <mgorman@...hsingularity.net>
Reviewed-by: Vlastimil Babka <vbabka@...e.cz>
---
 mm/page_alloc.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 3589febc6d31..08de32cfd9bb 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1432,10 +1432,10 @@ static bool bulkfree_pcp_prepare(struct page *page)
 }
 #endif /* CONFIG_DEBUG_VM */
 
-static inline void prefetch_buddy(struct page *page)
+static inline void prefetch_buddy(struct page *page, unsigned int order)
 {
 	unsigned long pfn = page_to_pfn(page);
-	unsigned long buddy_pfn = __find_buddy_pfn(pfn, 0);
+	unsigned long buddy_pfn = __find_buddy_pfn(pfn, order);
 	struct page *buddy = page + (buddy_pfn - pfn);
 
 	prefetch(buddy);
@@ -1512,7 +1512,7 @@ static void free_pcppages_bulk(struct zone *zone, int count,
 			 * prefetch buddy for the first pcp->batch nr of pages.
 			 */
 			if (prefetch_nr) {
-				prefetch_buddy(page);
+				prefetch_buddy(page, order);
 				prefetch_nr--;
 			}
 		} while (count > 0 && --batch_free && !list_empty(list));
-- 
2.31.1