Patch "memory-hotplug: add hot-added memory ranges to memblock before allocate node_data for a node." has been added to the 4.2-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

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

to the 4.2-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     memory-hotplug-add-hot-added-memory-ranges-to-memblock-before-allocate-node_data-for-a-node.patch
and it can be found in the queue-4.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 7f36e3e56db1ae75d1e157011b3cb2e0957f0a7e Mon Sep 17 00:00:00 2001
From: Tang Chen <tangchen@cn.fujitsu.com>
Date: Fri, 4 Sep 2015 15:42:32 -0700
Subject: memory-hotplug: add hot-added memory ranges to memblock before allocate node_data for a node.

From: Tang Chen <tangchen@cn.fujitsu.com>

commit 7f36e3e56db1ae75d1e157011b3cb2e0957f0a7e upstream.

Commit f9126ab9241f ("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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 mm/memory_hotplug.c |   10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1248,6 +1248,14 @@ int __ref add_memory(int nid, u64 start,
 
 	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,
 
 	/* 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();


Patches currently in stable-queue which might be from tangchen@cn.fujitsu.com are

queue-4.2/memory-hotplug-add-hot-added-memory-ranges-to-memblock-before-allocate-node_data-for-a-node.patch