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authorKirill A. Shutemov <kirill.shutemov@linux.intel.com>2016-01-15 16:52:07 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2016-01-15 17:56:32 -0800
commit1c290f642101e64f379e38ea0361d097c08e824d (patch)
tree14667c7c813fa14f6ce63e3fe7f5d14322fff0a6 /include/linux/poison.h
parent822cdd1152265d87fcfc974e06c3b68f762987fd (diff)
mm: sanitize page->mapping for tail pages
We don't define meaning of page->mapping for tail pages. Currently it's always NULL, which can be inconsistent with head page and potentially lead to problems. Let's poison the pointer to catch all illigal uses. page_rmapping(), page_mapping() and page_anon_vma() are changed to look on head page. The only illegal use I've caught so far is __GPF_COMP pages from sound subsystem, mapped with PTEs. do_shared_fault() is changed to use page_rmapping() instead of direct access to fault_page->mapping. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Jérôme Glisse <jglisse@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Steve Capper <steve.capper@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Jerome Marchand <jmarchan@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/poison.h')
-rw-r--r--include/linux/poison.h4
1 files changed, 4 insertions, 0 deletions
diff --git a/include/linux/poison.h b/include/linux/poison.h
index 317e16de09e5..76c3b6c38c16 100644
--- a/include/linux/poison.h
+++ b/include/linux/poison.h
@@ -32,6 +32,10 @@
/********** mm/debug-pagealloc.c **********/
#define PAGE_POISON 0xaa
+/********** mm/page_alloc.c ************/
+
+#define TAIL_MAPPING ((void *) 0x01014A11 + POISON_POINTER_DELTA)
+
/********** mm/slab.c **********/
/*
* Magic nums for obj red zoning.