Commit d2b20b11 authored by Gautham R Shenoy's avatar Gautham R Shenoy Committed by Linus Torvalds

Add irq protection in the percpu-counters cpu-hotplug-callback path

Some of the per-cpu counters and thus their locks are accessed from IRQ
contexts.  This can cause a deadlock if it interrupts a cpu-offline thread
which is transferring a dead-cpu's counts to the global counter.

Add appropriate IRQ protection in the cpu-hotplug callback path.
Signed-off-by: default avatarGautham R Shenoy <>
Cc: KAMEZAWA Hiroyuki <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 73e753a5
......@@ -124,12 +124,13 @@ static int __cpuinit percpu_counter_hotcpu_callback(struct notifier_block *nb,
list_for_each_entry(fbc, &percpu_counters, list) {
s32 *pcount;
unsigned long flags;
spin_lock_irqsave(&fbc->lock, flags);
pcount = per_cpu_ptr(fbc->counters, cpu);
fbc->count += *pcount;
*pcount = 0;
spin_unlock_irqrestore(&fbc->lock, flags);
return NOTIFY_OK;
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