Re: [PATCH v6 08/12] Handle async PF in a guest.

From: Avi Kivity
Date: Sat Oct 09 2010 - 14:49:18 EST


On 10/07/2010 08:03 PM, Gleb Natapov wrote:
> >>
> >Host side keeps track of outstanding apfs and will not send apf for the
> >same phys address twice. It will halt vcpu instead.
>
> What about different pages, running the scheduler code?
>
We can get couple of nested apfs, just like we can get nested
interrupts. Since scheduler disables preemption second apf will halt.

How much is a couple?

Consider:

SIGSTOP
Entire process swapped out
SIGCONT

We can get APF's on the current code, the scheduler code, the stack, any debugging code in between (e.g. ftrace), and the page tables for all of these.

--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

--
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/