linux-kernel - [PATCH] mm: kfence: fix handling discontiguous page

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Message-Id: <20230323025003.94447-1-songmuchun@bytedance.com>
Date:   Thu, 23 Mar 2023 10:50:03 +0800
From:   Muchun Song <songmuchun@...edance.com>
To:     glider@...gle.com, elver@...gle.com, dvyukov@...gle.com,
        akpm@...ux-foundation.org, jannh@...gle.com, sjpark@...zon.de,
        muchun.song@...ux.dev
Cc:     kasan-dev@...glegroups.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Muchun Song <songmuchun@...edance.com>
Subject: [PATCH] mm: kfence: fix handling discontiguous page

The struct pages could be discontiguous when the kfence pool is allocated
via alloc_contig_pages() with CONFIG_SPARSEMEM and !CONFIG_SPARSEMEM_VMEMMAP.
So, the iteration should use nth_page().

Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure")
Signed-off-by: Muchun Song <songmuchun@...edance.com>
---
 mm/kfence/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/kfence/core.c b/mm/kfence/core.c
index d66092dd187c..1065e0568d05 100644
--- a/mm/kfence/core.c
+++ b/mm/kfence/core.c
@@ -556,7 +556,7 @@ static unsigned long kfence_init_pool(void)
 	 * enters __slab_free() slow-path.
 	 */
 	for (i = 0; i < KFENCE_POOL_SIZE / PAGE_SIZE; i++) {
-		struct slab *slab = page_slab(&pages[i]);
+		struct slab *slab = page_slab(nth_page(pages, i));
 
 		if (!i || (i % 2))
 			continue;
@@ -602,7 +602,7 @@ static unsigned long kfence_init_pool(void)
 
 reset_slab:
 	for (i = 0; i < KFENCE_POOL_SIZE / PAGE_SIZE; i++) {
-		struct slab *slab = page_slab(&pages[i]);
+		struct slab *slab = page_slab(nth_page(pages, i));
 
 		if (!i || (i % 2))
 			continue;
-- 
2.11.0