From: zhong jiang zhongjiang@huawei.com
[ Upstream commit d6d8c8a48291b929b2e039f220f0b62958cccfea ]
When mainline introduced commit a96dfddbcc04 ("base/memory, hotplug: fix a kernel oops in show_valid_zones()"), it obtained the valid start and end pfn from the given pfn range. The valid start pfn can fix the actual issue, but it introduced another issue. The valid end pfn will may exceed the given end_pfn.
Although the incorrect overflow will not result in actual problem at present, but I think it need to be fixed.
[toshi.kani@hpe.com: remove assumption that end_pfn is aligned by MAX_ORDER_NR_PAGES] Fixes: a96dfddbcc04 ("base/memory, hotplug: fix a kernel oops in show_valid_zones()") Link: http://lkml.kernel.org/r/1486467299-22648-1-git-send-email-zhongjiang@huawei... Signed-off-by: zhong jiang zhongjiang@huawei.com Signed-off-by: Toshi Kani toshi.kani@hpe.com Cc: Vlastimil Babka vbabka@suse.cz Cc: Mel Gorman mgorman@techsingularity.net Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- mm/memory_hotplug.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 804cbfe9132dd..5fa8a3606f409 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1397,7 +1397,7 @@ int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn, while ((i < MAX_ORDER_NR_PAGES) && !pfn_valid_within(pfn + i)) i++; - if (i == MAX_ORDER_NR_PAGES) + if (i == MAX_ORDER_NR_PAGES || pfn + i >= end_pfn) continue; /* Check if we got outside of the zone */ if (zone && !zone_spans_pfn(zone, pfn + i)) @@ -1414,7 +1414,7 @@ int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn,
if (zone) { *valid_start = start; - *valid_end = end; + *valid_end = min(end, end_pfn); return 1; } else { return 0;