Commit 7f36e3e5 authored Sep 04, 2015 by Tang Chen Committed by Linus Torvalds Sep 04, 2015

memory-hotplug: add hot-added memory ranges to memblock before allocate node_data for a node.



Commit f9126ab9 ("memory-hotplug: fix wrong edge when hot add a new
node") hot-added memory range to memblock, after creating pgdat for new
node.

But there is a problem:

  add_memory()
  |--> hotadd_new_pgdat()
       |--> free_area_init_node()
            |--> get_pfn_range_for_nid()
                 |--> find start_pfn and end_pfn in memblock
  |--> ......
  |--> memblock_add_node(start, size, nid)    --------    Here, just too late.

get_pfn_range_for_nid() will find that start_pfn and end_pfn are both 0.
As a result, when adding memory, dmesg will give the following wrong
message.

  Initmem setup node 5 [mem 0x0000000000000000-0xffffffffffffffff]
  On node 5 totalpages: 0
  Built 5 zonelists in Node order, mobility grouping on.  Total pages: 32588823
  Policy zone: Normal
  init_memory_mapping: [mem 0x60000000000-0x607ffffffff]

The solution is simple, just add the memory range to memblock a little
earlier, before hotadd_new_pgdat().

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Taku Izumi <izumi.taku@jp.fujitsu.com>
Cc: Gu Zheng <guz.fnst@cn.fujitsu.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: David Rientjes <rientjes@google.com>
Cc: <stable@vger.kernel.org>	[4.2.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 88a99886

mm/memory_hotplug.c

+9 −1

Original line number	Diff line number	Diff line
		@@ -1248,6 +1248,14 @@ int __ref add_memory(int nid, u64 start, u64 size)

		mem_hotplug_begin();

		/*
		* Add new range to memblock so that when hotadd_new_pgdat() is called
		* to allocate new pgdat, get_pfn_range_for_nid() will be able to find
		* this new range and calculate total pages correctly. The range will
		* be removed at hot-remove time.
		*/
		memblock_add_node(start, size, nid);

		new_node = !node_online(nid);
		if (new_node) {
		pgdat = hotadd_new_pgdat(nid, start);
		@@ -1277,7 +1285,6 @@ int __ref add_memory(int nid, u64 start, u64 size)

		/* create new memmap entry */
		firmware_map_add_hotplug(start, start + size, "System RAM");
		memblock_add_node(start, size, nid);

		goto out;

		@@ -1286,6 +1293,7 @@ error:
		if (new_pgdat)
		rollback_node_hotadd(nid, pgdat);
		release_memory_resource(res);
		memblock_remove(start, size);

		out:
		mem_hotplug_done();

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