Re: kvm: RCU warning in async pf

[Sasha Levin]

On Wed, Apr 4, 2012 at 2:30 PM, Gleb Natapov <gleb@xxxxxxxxxx> wrote:
> On Tue, Apr 03, 2012 at 01:52:26PM +0300, Gleb Natapov wrote:
>> On Mon, Apr 02, 2012 at 08:54:32PM -0400, Sasha Levin wrote:
>> > Hi all,
>> >
>> > I got the spew at the bottom of the mail in a KVM guest using the KVM tools and running trinity.
>> >
>> > I'm not quite sure how default_idle managed to trigger a pagefault, so that part looks odd to me.
>> >
>> This is not regular page fault. This is async page fault that tells the
>> guest that a page, previously swapped out by hypervisor, is now swapped
>> back in and it can happen while vcpu is idle. The code does not leave
>> idle state properly though. We probably need to call rcu_irq_enter()
>> there. Will look into it.
>>
>
> The patch below solves it for me:
>
> "Page ready" async PF can kick vcpu out of idle state much like IRQ.
> We need to tell RCU about this.

Looks good here.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/