mm, nobootmem: do memset() after memblock_reserve()

Currently, we do memset() before reserving the area.  This may not cause
any problem, but it is somewhat weird.  So change execution order.
Signed-off-by: NJoonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Jiang Liu <liuj97@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/nobootmem.c

@@ -45,9 +45,9 @@ static void * __init __alloc_memory_core_early(int nid, u64 size, u64 align,
 	if (!addr)
 		return NULL;
 
+	memblock_reserve(addr, size);
 	ptr = phys_to_virt(addr);
 	memset(ptr, 0, size);
-	memblock_reserve(addr, size);
 	/*
 	 * The min_count is set to 0 so that bootmem allocated blocks
 	 * are never reported as leaks.