+ mm-kfence-fix-handling-discontiguous-page.patch added to mm-hotfixes-unstable branch

+ mm-kfence-fix-handling-discontiguous-page.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm: kfence: fix handling discontiguous page
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-kfence-fix-handling-discontiguous-page.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-kfence-fix-handling-discontiguous-page.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Muchun Song <songmuchun@bytedance.com>
Subject: mm: kfence: fix handling discontiguous page
Date: Thu, 23 Mar 2023 10:50:03 +0800

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().

Link: https://lkml.kernel.org/r/20230323025003.94447-1-songmuchun@bytedance.com
Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: SeongJae Park <sjpark@amazon.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/kfence/core.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/mm/kfence/core.c~mm-kfence-fix-handling-discontiguous-page
+++ a/mm/kfence/core.c
@@ -556,7 +556,7 @@ static unsigned long kfence_init_pool(vo
 	 * 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(vo
 
 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;
_

Patches currently in -mm which might be from songmuchun@bytedance.com are

mm-kfence-fix-pg_slab-and-memcg_data-clearing.patch
mm-kfence-fix-handling-discontiguous-page.patch
mm-hugetlb_vmemmap-simplify-hugetlb_vmemmap_init-a-bit.patch