On 13 Sep 2023, at 16:12, Zi Yan wrote:
From: Zi Yan ziy@nvidia.com
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.
Fixes: 57a196a58421 ("hugetlb: simplify hugetlb handling in follow_page_mask") Cc: stable@vger.kernel.org Signed-off-by: Zi Yan ziy@nvidia.com Reviewed-by: Muchun Song songmuchun@bytedance.com
mm/hugetlb.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index af74e83d92aa..8e68e6c53e66 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -6469,7 +6469,7 @@ struct page *hugetlb_follow_page_mask(struct vm_area_struct *vma, } }
page += ((address & ~huge_page_mask(h)) >> PAGE_SHIFT);
page = nth_page(page, ((address & ~huge_page_mask(h)) >> PAGE_SHIFT));/*
- Note that page may be a sub-page, and with vmemmap
-- 2.40.1
A wrong or non-existing page might be tried to be grabbed, either leading to a non freeable page or kernel memory access errors. No bug is reported. It comes from code inspection.
-- Best Regards, Yan, Zi