From: Muchun Song <songmuchun@xxxxxxxxxxxxx> Subject: mm: hugetlb: fix missing cache flush in copy_huge_page_from_user() userfaultfd calls copy_huge_page_from_user() which does not do any cache flushing for the target page. Then the target page will be mapped to the user space with a different address (user address), which might have an alias issue with the kernel address used to copy the data from the user to. Fix this issue by flushing dcache in copy_huge_page_from_user(). Link: https://lkml.kernel.org/r/20220210123058.79206-4-songmuchun@xxxxxxxxxxxxx Fixes: fa4d75c1de13 ("userfaultfd: hugetlbfs: add copy_huge_page_from_user for hugetlb userfaultfd support") Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx> Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Cc: Axel Rasmussen <axelrasmussen@xxxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: Fam Zheng <fam.zheng@xxxxxxxxxxxxx> Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Cc: Lars Persson <lars.persson@xxxxxxxx> Cc: Peter Xu <peterx@xxxxxxxxxx> Cc: Xiongchun Duan <duanxiongchun@xxxxxxxxxxxxx> Cc: Zi Yan <ziy@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/memory.c | 2 ++ 1 file changed, 2 insertions(+) --- a/mm/memory.c~mm-hugetlb-fix-missing-cache-flush-in-copy_huge_page_from_user +++ a/mm/memory.c @@ -5444,6 +5444,8 @@ long copy_huge_page_from_user(struct pag if (rc) break; + flush_dcache_page(subpage); + cond_resched(); } return ret_val; _
