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authorSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>2014-03-11 02:12:27 +0530
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2014-03-20 13:43:48 +0100
commit0be94bad0b601df94b8558c0cbd28f7e6633c9e8 (patch)
tree21dab481dd764a7b18d6671c1f79f7dcbf552b20
parentc270a817196a9374a2dc730624d1501dced40b4d (diff)
downloadblackbird-op-linux-0be94bad0b601df94b8558c0cbd28f7e6633c9e8.tar.gz
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mm, vmstat: Fix CPU hotplug callback registration
Subsystems that want to register CPU hotplug callbacks, as well as perform initialization for the CPUs that are already online, often do it as shown below: get_online_cpus(); for_each_online_cpu(cpu) init_cpu(cpu); register_cpu_notifier(&foobar_cpu_notifier); put_online_cpus(); This is wrong, since it is prone to ABBA deadlocks involving the cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently with CPU hotplug operations). Instead, the correct and race-free way of performing the callback registration is: cpu_notifier_register_begin(); for_each_online_cpu(cpu) init_cpu(cpu); /* Note the use of the double underscored version of the API */ __register_cpu_notifier(&foobar_cpu_notifier); cpu_notifier_register_done(); Fix the vmstat code in the MM subsystem by using this latter form of callback registration. Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Toshi Kani <toshi.kani@hp.com> Cc: Dave Hansen <dave@sr71.net> Cc: Ingo Molnar <mingo@kernel.org> Acked-by: Christoph Lameter <cl@linux.com> Acked-by: Rik van Riel <riel@redhat.com> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
-rw-r--r--mm/vmstat.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/mm/vmstat.c b/mm/vmstat.c
index def5dd2fbe61..58c6f3d09735 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1292,14 +1292,14 @@ static int __init setup_vmstat(void)
#ifdef CONFIG_SMP
int cpu;
- register_cpu_notifier(&vmstat_notifier);
+ cpu_notifier_register_begin();
+ __register_cpu_notifier(&vmstat_notifier);
- get_online_cpus();
for_each_online_cpu(cpu) {
start_cpu_timer(cpu);
node_set_state(cpu_to_node(cpu), N_CPU);
}
- put_online_cpus();
+ cpu_notifier_register_done();
#endif
#ifdef CONFIG_PROC_FS
proc_create("buddyinfo", S_IRUGO, NULL, &fragmentation_file_operations);
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