4.2-stable review patch. If anyone has any objections, please let me know.
------------------
From: Tang Chen <tangc...@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().
[a...@linux-foundation.org: coding-style fixes]
Signed-off-by: Tang Chen <tangc...@cn.fujitsu.com>
Cc: Xishi Qiu <qiuxi...@huawei.com>
Cc: Yasuaki Ishimatsu <isimatu.yasu...@jp.fujitsu.com>
Cc: Kamezawa Hiroyuki <kamezawa.hir...@jp.fujitsu.com>
Cc: Taku Izumi <izumi.t...@jp.fujitsu.com>
Cc: Gu Zheng <guz.f...@cn.fujitsu.com>
Cc: Naoya Horiguchi <n-horigu...@ah.jp.nec.com>
Cc: Vlastimil Babka <vba...@suse.cz>
Cc: Mel Gorman <mgor...@techsingularity.net>
Cc: David Rientjes <rient...@google.com>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gre...@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();
--
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