Commit c7991b0b authored Aug 13, 2013 by Rafael J. Wysocki Committed by Greg Kroah-Hartman Aug 12, 2013

driver core / cpu: Check if NUMA node is valid before bringing CPU up

There is a potential race condition between cpu_subsys_online()
and either acpi_processor_remove() or remove_memory() that execute
try_offline_node(). Namely, it is possible that cpu_subsys_online()
will run right after the CPUs NUMA node has been put offline and
cpu_to_node() executed by it will return NUMA_NO_NODE (-1). In
that case the CPU is gone and it doesn't make sense to call cpu_up()
for it, so make cpu_subsys_online() return -ENODEV then.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 910f5c7c

drivers/base/cpu.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -43,11 +43,14 @@ static int __ref cpu_subsys_online(struct device *dev)
		struct cpu *cpu = container_of(dev, struct cpu, dev);
		int cpuid = dev->id;
		int from_nid, to_nid;
		int ret;
		int ret = -ENODEV;

		cpu_hotplug_driver_lock();

		from_nid = cpu_to_node(cpuid);
		if (from_nid == NUMA_NO_NODE)
		goto out;

		ret = cpu_up(cpuid);
		/*
		* When hot adding memory to memoryless node and enabling a cpu
		@@ -57,6 +60,7 @@ static int __ref cpu_subsys_online(struct device *dev)
		if (from_nid != to_nid)
		change_cpu_under_node(cpu, from_nid, to_nid);

		out:
		cpu_hotplug_driver_unlock();
		return ret;
		}

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