[PATCH] mm/memblock: fix potential issue in memblock_search_pfn_nid()

[Wei Yang <richard.weiyang@gmail.com>]

memblock_search_pfn_nid() returns the nid and the [start|end]_pfn of the
memory region where pfn sits in. While the calculation of start_pfn has
potential issue when the regions base is not page aligned.

For example, we assume PAGE_SHIFT is 12 and base is 0x1234. Current
implementation would return 1 while this is not correct.

This patch fixes this by using PFN_UP().

The original commit is commit e76b63f80d93 ("memblock, numa: binary search
node id") and merged in v3.12.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Cc: 3.12+ <stable@vger.kernel.org>

---
* add He Jia in cc
* fix the mm mail list address
* Cc: 3.12+

---
 mm/memblock.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/memblock.c b/mm/memblock.c
index b6ba6b7adadc..de768307696d 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -1673,7 +1673,7 @@ int __init_memblock memblock_search_pfn_nid(unsigned long pfn,
 	if (mid == -1)
 		return -1;
 
-	*start_pfn = PFN_DOWN(type->regions[mid].base);
+	*start_pfn = PFN_UP(type->regions[mid].base);
 	*end_pfn = PFN_DOWN(type->regions[mid].base + type->regions[mid].size);
 
 	return type->regions[mid].nid;
-- 
2.15.1