The patch titled
Subject: mm: don't dereference struct page fields of invalid pages
has been added to the -mm tree. Its filename is
mm-dont-dereference-struct-page-fields-of-invalid-pages.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-dont-dereference-struct-page-fields-of-invalid-pages.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-dont-dereference-struct-page-fields-of-invalid-pages.patch
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------------------------------------------------------
From: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Subject: mm: don't dereference struct page fields of invalid pages
The VM_BUG_ON() check in move_freepages() checks whether the node id of a
page matches the node id of its zone. However, it does this before having
checked whether the struct page pointer refers to a valid struct page to
begin with. This is guaranteed in most cases, but may not be the case if
CONFIG_HOLES_IN_ZONE=y.
So reorder the VM_BUG_ON() with the pfn_valid_within() check.
Link: http://lkml.kernel.org/r/1481706707-6211-2-git-send-email-ard.biesheuvel@xxxxxxxxxx
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
Cc: Yisheng Xie <xieyisheng1@xxxxxxxxxx>
Cc: Robert Richter <rrichter@xxxxxxxxxx>
Cc: James Morse <james.morse@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff -puN mm/page_alloc.c~mm-dont-dereference-struct-page-fields-of-invalid-pages mm/page_alloc.c
--- a/mm/page_alloc.c~mm-dont-dereference-struct-page-fields-of-invalid-pages
+++ a/mm/page_alloc.c
@@ -1864,14 +1864,14 @@ int move_freepages(struct zone *zone,
#endif
for (page = start_page; page <= end_page;) {
- /* Make sure we are not inadvertently changing nodes */
- VM_BUG_ON_PAGE(page_to_nid(page) != zone_to_nid(zone), page);
-
if (!pfn_valid_within(page_to_pfn(page))) {
page++;
continue;
}
+ /* Make sure we are not inadvertently changing nodes */
+ VM_BUG_ON_PAGE(page_to_nid(page) != zone_to_nid(zone), page);
+
if (!PageBuddy(page)) {
page++;
continue;
_
Patches currently in -mm which might be from ard.biesheuvel@xxxxxxxxxx are
mm-dont-dereference-struct-page-fields-of-invalid-pages.patch
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