From 7f36e3e56db1ae75d1e157011b3cb2e0957f0a7e Mon Sep 17 00:00:00 2001 From: Tang Chen Date: Fri, 4 Sep 2015 15:42:32 -0700 Subject: [PATCH] memory-hotplug: add hot-added memory ranges to memblock before allocate node_data for a node. 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 Cc: Xishi Qiu Cc: Yasuaki Ishimatsu Cc: Kamezawa Hiroyuki Cc: Taku Izumi Cc: Gu Zheng Cc: Naoya Horiguchi Cc: Vlastimil Babka Cc: Mel Gorman Cc: David Rientjes Cc: [4.2.x] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memory_hotplug.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 6da82bcb0a8b..8fd97dac538a 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -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(); -- 2.20.1