From 84d20fbb332ee6ca2d3cffd284168151a2eca164 Mon Sep 17 00:00:00 2001 From: Zi Yan Date: Wed, 13 Sep 2023 16:12:44 -0400 Subject: [PATCH] UPSTREAM: 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. Bug: 254441685 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 Reviewed-by: Muchun Song Cc: David Hildenbrand Cc: Matthew Wilcox (Oracle) Cc: Mike Kravetz Cc: Mike Rapoport (IBM) Cc: Thomas Bogendoerfer Cc: Signed-off-by: Andrew Morton (cherry picked from commit 2e7cfe5cd5b6b0b98abf57a3074885979e187c1c) Signed-off-by: Lee Jones Change-Id: Ib62455867ec73728b47f7f93e809bd6d0131208a --- mm/cma.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/cma.c b/mm/cma.c index e2b95d4fdebc..4ae61aea55a5 100644 --- a/mm/cma.c +++ b/mm/cma.c @@ -497,7 +497,7 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align, */ 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) {