diff mbox series

[v5,4/7] mm: hugetlb: fix missing cache flush in hugetlb_mcopy_atomic_pte()

Message ID 20220210123058.79206-5-songmuchun@bytedance.com (mailing list archive)
State New
Headers show
Series Fix some cache flush bugs | expand

Commit Message

Muchun Song Feb. 10, 2022, 12:30 p.m. UTC 
folio_copy() will copy the data from one page to the target page, then
the target page will be mapped to the user space address, which might
have an alias issue with the kernel address used to copy the data from
the page to.  There are 2 ways to fix this issue.

 1) insert flush_dcache_page() after folio_copy().
 2) replace folio_copy() with copy_user_huge_page() which already
    considers the cache maintenance.

We chose 2) way to fix the issue since architectures can optimize this
situation.  It is also make backports easier.

Fixes: 8cc5fcbb5be8 ("mm, hugetlb: fix racy resv_huge_pages underflow on UFFDIO_COPY")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
---
 mm/hugetlb.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index a1baa198519a..eba7681d15d0 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5818,7 +5818,8 @@  int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
 			*pagep = NULL;
 			goto out;
 		}
-		folio_copy(page_folio(page), page_folio(*pagep));
+		copy_user_huge_page(page, *pagep, dst_addr, dst_vma,
+				    pages_per_huge_page(h));
 		put_page(*pagep);
 		*pagep = NULL;
 	}