5.4-stable review patch. If anyone has any objections, please let me know.
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From: Zi Yan ziy@nvidia.com
commit 2e7cfe5cd5b6b0b98abf57a3074885979e187c1c upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/cma.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/cma.c +++ b/mm/cma.c @@ -481,7 +481,7 @@ struct page *cma_alloc(struct cma *cma, */ 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) {