mem-hotplug: fix node spanned pages when we have a movable node

mem-hotplug: fix node spanned pages when we have a movable node

342332e6a925e9e ("mm/page_alloc.c: introduce kernelcore=mirror option")
rewrote the calculation of node spanned pages.  But when we have a movable
node, the size of node spanned pages is double added.  That's because we
have an empty normal zone, the present pages is zero, but its spanned
pages is not zero.

e.g.
[    0.000000] Zone ranges:
[    0.000000]   DMA      [mem 0x0000000000001000-0x0000000000ffffff]
[    0.000000]   DMA32    [mem 0x0000000001000000-0x00000000ffffffff]
[    0.000000]   Normal   [mem 0x0000000100000000-0x0000007c7fffffff]
[    0.000000] Movable zone start for each node
[    0.000000]   Node 1: 0x0000001080000000
[    0.000000]   Node 2: 0x0000002080000000
[    0.000000]   Node 3: 0x0000003080000000
[    0.000000]   Node 4: 0x0000003c80000000
[    0.000000]   Node 5: 0x0000004c80000000
[    0.000000]   Node 6: 0x0000005c80000000
[    0.000000] Early memory node ranges
[    0.000000]   node   0: [mem 0x0000000000001000-0x000000000009ffff]
[    0.000000]   node   0: [mem 0x0000000000100000-0x000000007552afff]
[    0.000000]   node   0: [mem 0x000000007bd46000-0x000000007bd46fff]
[    0.000000]   node   0: [mem 0x000000007bdcd000-0x000000007bffffff]
[    0.000000]   node   0: [mem 0x0000000100000000-0x000000107fffffff]
[    0.000000]   node   1: [mem 0x0000001080000000-0x000000207fffffff]
[    0.000000]   node   2: [mem 0x0000002080000000-0x000000307fffffff]
[    0.000000]   node   3: [mem 0x0000003080000000-0x0000003c7fffffff]
[    0.000000]   node   4: [mem 0x0000003c80000000-0x0000004c7fffffff]
[    0.000000]   node   5: [mem 0x0000004c80000000-0x0000005c7fffffff]
[    0.000000]   node   6: [mem 0x0000005c80000000-0x0000006c7fffffff]
[    0.000000]   node   7: [mem 0x0000006c80000000-0x0000007c7fffffff]

node1:
[  760.227767] Normal, start=0x1080000, present=0x0, spanned=0x1000000
[  760.234024] Movable, start=0x1080000, present=0x1000000, spanned=0x1000000
[  760.240883] pgdat, start=0x1080000, present=0x1000000, spanned=0x2000000

After apply this patch, the problem is fixed.
node1:
[  289.770922] Normal, start=0x0, present=0x0, spanned=0x0
[  289.776153] Movable, start=0x1080000, present=0x1000000, spanned=0x1000000
[  289.783019] pgdat, start=0x1080000, present=0x1000000, spanned=0x1000000

Link: http://lkml.kernel.org/r/57A325E8.6070100@huawei.com
Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
Cc: Taku Izumi <izumi.taku@jp.fujitsu.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>