Commit 0798d3c0 authored May 27, 2016 by Kirill A. Shutemov Committed by Linus Torvalds May 27, 2016

mm: thp: avoid false positive VM_BUG_ON_PAGE in page_move_anon_rmap()

If page_move_anon_rmap() is refiling a pmd-splitted THP mapped in a tail
page from a pte, the "address" must be THP aligned in order for the
page->index bugcheck to pass in the CONFIG_DEBUG_VM=y builds.

Link: http://lkml.kernel.org/r/1464253620-106404-1-git-send-email-kirill.shutemov@linux.intel.com

Fixes: 6d0a07ed ("mm: thp: calculate the mapcount correctly for THP pages during WP faults")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: <stable@vger.kernel.org> [4.5]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent e2fe1456

mm/rmap.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -1098,6 +1098,8 @@ void page_move_anon_rmap(struct page *page,

		VM_BUG_ON_PAGE(!PageLocked(page), page);
		VM_BUG_ON_VMA(!anon_vma, vma);
		if (IS_ENABLED(CONFIG_DEBUG_VM) && PageTransHuge(page))
		address &= HPAGE_PMD_MASK;
		VM_BUG_ON_PAGE(page->index != linear_page_index(vma, address), page);

		anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;