mm/huge_memory: fix copying user highpage

The THP copy-on-write handler falls back to regular-sized pages for a huge
page replacement upon allocation failure or if THP has been individually
disabled in the target VMA.  The loop responsible for copying page-sized
chunks accidentally uses multiples of PAGE_SHIFT instead of PAGE_SIZE as
the virtual address arg for copy_user_highpage().

Signed-off-by: Hillf Danton <dhillf@gmail.com>
Acked-by: Johannes Weiner <jweiner@redhat.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 44f5763..ef95438 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -830,7 +830,7 @@ static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
 
        for (i = 0; i < HPAGE_PMD_NR; i++) {
                copy_user_highpage(pages[i], page + i,
-                                  haddr + PAGE_SHIFT*i, vma);
+                                  haddr + PAGE_SIZE * i, vma);
                __SetPageUptodate(pages[i]);
                cond_resched();
        }