From: Laura Abbott <[email protected]>
This patch has been added to the 3.18 stable tree. If you have any
objections, please let us know.
===============
[ Upstream commit cfa869438282be84ad4110bba5027ef1fbbe71e4 ]
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
fault:
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 <[email protected]>
Cc: Naoya Horiguchi <[email protected]>
Cc: Mel Gorman <[email protected]>
Acked-by: Rik van Riel <[email protected]>
Cc: Yasuaki Ishimatsu <[email protected]>
Cc: Zhang Yanfei <[email protected]>
Cc: Xishi Qiu <[email protected]>
Cc: Vladimir Davydov <[email protected]>
Acked-by: Joonsoo Kim <[email protected]>
Cc: Gioh Kim <[email protected]>
Cc: Michal Nazarewicz <[email protected]>
Cc: Marek Szyprowski <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
---
mm/page_isolation.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index c8778f7..ec66134 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -103,6 +103,7 @@ void unset_migratetype_isolate(struct page *page, unsigned
migratetype)
if (!is_migrate_isolate_page(buddy)) {
__isolate_free_page(page, order);
+ kernel_map_pages(page, (1 << order), 1);
set_page_refcounted(page);
isolated_page = page;
}
--
2.1.0
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