From: Weijie Yang <weijie.yang@xxxxxxxxxxx>
Subject: mm: page_isolation: check pfn validity before access
In the undo path of start_isolate_page_range(), we need to check the pfn
validity before accessing its page, or it will trigger an addressing
exception if there is hole in the zone.
This issue is found by code-review not a test-trigger. In
"CONFIG_HOLES_IN_ZONE" environment, there is a certain chance that it
would casue an addressing exception when start_isolate_page_range()
fails, this could affect CMA, hugepage and memory-hotplug function.
Signed-off-by: Weijie Yang <weijie.yang@xxxxxxxxxxx>
Acked-by: Michal Nazarewicz <mina86@xxxxxxxxxx>
Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Mel Gorman <mel@xxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_isolation.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff -puN mm/page_isolation.c~mm-page_isolation-check-pfn-validity-before-access mm/page_isolation.c
--- a/mm/page_isolation.c~mm-page_isolation-check-pfn-validity-before-access
+++ a/mm/page_isolation.c
@@ -176,8 +176,11 @@ int start_isolate_page_range(unsigned lo
undo:
for (pfn = start_pfn;
pfn < undo_pfn;
- pfn += pageblock_nr_pages)
- unset_migratetype_isolate(pfn_to_page(pfn), migratetype);
+ pfn += pageblock_nr_pages) {
+ page = __first_valid_page(pfn, pageblock_nr_pages);
+ if (page)
+ unset_migratetype_isolate(page, migratetype);
+ }
return -EBUSY;
}
_
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