[PATCH] memblock: fix memblock_next_valid_pfn()

[AKASHI Takahiro]

Obviously, we should not access memblock.memory.regions[right]
if 'right' is outside of [0..memblock.memory.cnt>.

Fixes: b92df1de5d28 ("mm: page_alloc: skip over regions of invalid pfns where possible")
Signed-off-by: AKASHI Takahiro <takahiro.akashi@xxxxxxxxxx>
---
 mm/memblock.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/mm/memblock.c b/mm/memblock.c
index b64b47803e52..696f06d17c4e 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -1118,7 +1118,10 @@ unsigned long __init_memblock memblock_next_valid_pfn(unsigned long pfn,
 		}
 	} while (left < right);
 
-	return min(PHYS_PFN(type->regions[right].base), max_pfn);
+	if (right == type->cnt)
+		return max_pfn;
+	else
+		return min(PHYS_PFN(type->regions[right].base), max_pfn);
 }
 
 /**
-- 
2.11.1