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Subject[PATCH 3.19 045/101] mm/page_alloc.c: call kernel_map_pages in unset_migrateype_isolate
3.19-stable review patch.  If anyone has any objections, please let me know.


From: Laura Abbott <>

commit cfa869438282be84ad4110bba5027ef1fbbe71e4 upstream.

Commit 3c605096d315 ("mm/page_alloc: restrict max order of merging on
isolated pageblock") changed the logic of unset_migratetype_isolate to
check the buddy allocator and explicitly call __free_pages to merge.

The page that is being freed in this path never had prep_new_page called
so set_page_refcounted is called explicitly but there is no call to
kernel_map_pages. With the default kernel_map_pages this is mostly
harmless but if kernel_map_pages does any manipulation of the page
tables (unmapping or setting pages to read only) this may trigger a

alloc_contig_range test_pages_isolated(ceb00, ced00) failed
Unable to handle kernel paging request at virtual address ffffffc0cec00000
pgd = ffffffc045fc4000
[ffffffc0cec00000] *pgd=0000000000000000
Internal error: Oops: 9600004f [#1] PREEMPT SMP
Modules linked in: exfatfs
CPU: 1 PID: 23237 Comm: TimedEventQueue Not tainted 3.10.49-gc72ad36-dirty #1
task: ffffffc03de52100 ti: ffffffc015388000 task.ti: ffffffc015388000
PC is at memset+0xc8/0x1c0
LR is at kernel_map_pages+0x1ec/0x244

Fix this by calling kernel_map_pages to ensure the page is set in the
page table properly

Fixes: 3c605096d315 ("mm/page_alloc: restrict max order of merging on isolated pageblock")
Signed-off-by: Laura Abbott <>
Cc: Naoya Horiguchi <>
Cc: Mel Gorman <>
Acked-by: Rik van Riel <>
Cc: Yasuaki Ishimatsu <>
Cc: Zhang Yanfei <>
Cc: Xishi Qiu <>
Cc: Vladimir Davydov <>
Acked-by: Joonsoo Kim <>
Cc: Gioh Kim <>
Cc: Michal Nazarewicz <>
Cc: Marek Szyprowski <>
Cc: Vlastimil Babka <>
Signed-off-by: Andrew Morton <>
Signed-off-by: Linus Torvalds <>
Signed-off-by: Greg Kroah-Hartman <>

mm/page_isolation.c | 1 +
1 file changed, 1 insertion(+)

--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -103,6 +103,7 @@ void unset_migratetype_isolate(struct pa

if (!is_migrate_isolate_page(buddy)) {
__isolate_free_page(page, order);
+ kernel_map_pages(page, (1 << order), 1);
isolated_page = page;

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