linux-kernel - [v2 PATCH 1/9] mm: define N_CPU

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Date:   Thu, 11 Apr 2019 11:56:51 +0800
From:   Yang Shi <yang.shi@...ux.alibaba.com>
To:     mhocko@...e.com, mgorman@...hsingularity.net, riel@...riel.com,
        hannes@...xchg.org, akpm@...ux-foundation.org,
        dave.hansen@...el.com, keith.busch@...el.com,
        dan.j.williams@...el.com, fengguang.wu@...el.com, fan.du@...el.com,
        ying.huang@...el.com, ziy@...dia.com
Cc:     yang.shi@...ux.alibaba.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [v2 PATCH 1/9] mm: define N_CPU_MEM node states

Kernel has some pre-defined node masks called node states, i.e.
N_MEMORY, N_CPU, etc.  But, there might be cpuless nodes, i.e. PMEM
nodes, and some architectures, i.e. Power, may have memoryless nodes.
It is not very straight forward to get the nodes with both CPUs and
memory.  So, define N_CPU_MEMORY node states.  The nodes with both CPUs
and memory are called "primary" nodes.  /sys/devices/system/node/primary
would show the current online "primary" nodes.

Signed-off-by: Yang Shi <yang.shi@...ux.alibaba.com>
---
 drivers/base/node.c      |  2 ++
 include/linux/nodemask.h |  3 ++-
 mm/memory_hotplug.c      |  6 ++++++
 mm/page_alloc.c          |  1 +
 mm/vmstat.c              | 11 +++++++++--
 5 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/drivers/base/node.c b/drivers/base/node.c
index 86d6cd9..1b963b2 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -634,6 +634,7 @@ static ssize_t show_node_state(struct device *dev,
 #endif
 	[N_MEMORY] = _NODE_ATTR(has_memory, N_MEMORY),
 	[N_CPU] = _NODE_ATTR(has_cpu, N_CPU),
+	[N_CPU_MEM] = _NODE_ATTR(primary, N_CPU_MEM),
 };
 
 static struct attribute *node_state_attrs[] = {
@@ -645,6 +646,7 @@ static ssize_t show_node_state(struct device *dev,
 #endif
 	&node_state_attr[N_MEMORY].attr.attr,
 	&node_state_attr[N_CPU].attr.attr,
+	&node_state_attr[N_CPU_MEM].attr.attr,
 	NULL
 };
 
diff --git a/include/linux/nodemask.h b/include/linux/nodemask.h
index 27e7fa3..66a8964 100644
--- a/include/linux/nodemask.h
+++ b/include/linux/nodemask.h
@@ -398,7 +398,8 @@ enum node_states {
 	N_HIGH_MEMORY = N_NORMAL_MEMORY,
 #endif
 	N_MEMORY,		/* The node has memory(regular, high, movable) */
-	N_CPU,		/* The node has one or more cpus */
+	N_CPU,			/* The node has one or more cpus */
+	N_CPU_MEM,		/* The node has both cpus and memory */
 	NR_NODE_STATES
 };
 
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index f767582..1140f3b 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -729,6 +729,9 @@ static void node_states_set_node(int node, struct memory_notify *arg)
 
 	if (arg->status_change_nid >= 0)
 		node_set_state(node, N_MEMORY);
+
+	if (node_state(node, N_CPU))
+		node_set_state(node, N_CPU_MEM);
 }
 
 static void __meminit resize_zone_range(struct zone *zone, unsigned long start_pfn,
@@ -1569,6 +1572,9 @@ static void node_states_clear_node(int node, struct memory_notify *arg)
 
 	if (arg->status_change_nid >= 0)
 		node_clear_state(node, N_MEMORY);
+
+	if (node_state(node, N_CPU))
+		node_clear_state(node, N_CPU_MEM);
 }
 
 static int __ref __offline_pages(unsigned long start_pfn,
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 03fcf73..7cd88a4 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -122,6 +122,7 @@ struct pcpu_drain {
 #endif
 	[N_MEMORY] = { { [0] = 1UL } },
 	[N_CPU] = { { [0] = 1UL } },
+	[N_CPU_MEM] = { { [0] = 1UL } },
 #endif	/* NUMA */
 };
 EXPORT_SYMBOL(node_states);
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 36b56f8..1a431dc 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1910,15 +1910,22 @@ static void __init init_cpu_node_state(void)
 	int node;
 
 	for_each_online_node(node) {
-		if (cpumask_weight(cpumask_of_node(node)) > 0)
+		if (cpumask_weight(cpumask_of_node(node)) > 0) {
 			node_set_state(node, N_CPU);
+			if (node_state(node, N_MEMORY))
+				node_set_state(node, N_CPU_MEM);
+		}
 	}
 }
 
 static int vmstat_cpu_online(unsigned int cpu)
 {
+	int node = cpu_to_node(cpu);
+
 	refresh_zone_stat_thresholds();
-	node_set_state(cpu_to_node(cpu), N_CPU);
+	node_set_state(node, N_CPU);
+	if (node_state(node, N_MEMORY))
+		node_set_state(node, N_CPU_MEM);
 	return 0;
 }
 
-- 
1.8.3.1