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>

diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 4c358bc44c72b1082d5576ed2ba6a93415b00563..6bfaaca6955e1d4ddcaf5b66a6c8af9022c0932b 100644 (file)
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -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;
 }