From 2e7cfe5cd5b6b0b98abf57a3074885979e187c1c Mon Sep 17 00:00:00 2001
From: Zi Yan <ziy@nvidia.com>
Date: Wed, 13 Sep 2023 16:12:44 -0400
Subject: [PATCH] mm/cma: use nth_page() in place of direct struct page
manipulation
Patch series "Use nth_page() in place of direct struct page manipulation",
v3.
On SPARSEMEM without VMEMMAP, struct page is not guaranteed to be
contiguous, since each memory section's memmap might be allocated
independently. hugetlb pages can go beyond a memory section size, thus
direct struct page manipulation on hugetlb pages/subpages might give wrong
struct page. Kernel provides nth_page() to do the manipulation properly.
Use that whenever code can see hugetlb pages.
This patch (of 5):
When dealing with hugetlb pages, manipulating struct page pointers
directly can get to wrong struct page, since struct page is not guaranteed
to be contiguous on SPARSEMEM without VMEMMAP. Use nth_page() to handle
it properly.
Without the fix, page_kasan_tag_reset() could reset wrong page tags,
causing a wrong kasan result. No related bug is reported. The fix
comes from code inspection.
Link: https://lkml.kernel.org/r/20230913201248.452081-1-zi.yan@sent.com
Link: https://lkml.kernel.org/r/20230913201248.452081-2-zi.yan@sent.com
Fixes: 2813b9c02962 ("kasan, mm, arm64: tag non slab memory allocated via pagealloc")
Signed-off-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/cma.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/cma.c b/mm/cma.c
index da2967c6a2238..2b2494fd6b59a 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -505,7 +505,7 @@ struct page *cma_alloc(struct cma *cma, unsigned long count,
*/
if (page) {
for (i = 0; i < count; i++)
- page_kasan_tag_reset(page + i);
+ page_kasan_tag_reset(nth_page(page, i));
}
if (ret && !no_warn) {
--
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