KVM: use is_idle_task() instead of idle_cpu() to decide when to halt in async_pf (859f8450) · Commits · 戴 / test

As Frederic pointed idle_cpu() may return false even if async fault happened in the idle task if wake up is pending. In this case the code will try to put idle task to sleep. Fix this by using is_idle_task() to check for idle task. Reported-by:

Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by:

Gleb Natapov <gleb@redhat.com> Signed-off-by:

Marcelo Tosatti <mtosatti@redhat.com>

arch/x86/kernel/kvm.c

+1 −6

Original line number	Diff line number	Diff line
		@@ -120,11 +120,6 @@ void kvm_async_pf_task_wait(u32 token)
		struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
		struct kvm_task_sleep_node n, *e;
		DEFINE_WAIT(wait);
		int cpu, idle;

		cpu = get_cpu();
		idle = idle_cpu(cpu);
		put_cpu();

		spin_lock(&b->lock);
		e = _find_apf_task(b, token);
		@@ -138,7 +133,7 @@ void kvm_async_pf_task_wait(u32 token)

		n.token = token;
		n.cpu = smp_processor_id();
		n.halted = idle \|\| preempt_count() > 1;
		n.halted = is_idle_task(current) \|\| preempt_count() > 1;
		init_waitqueue_head(&n.wq);
		hlist_add_head(&n.link, &b->list);
		spin_unlock(&b->lock);

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