Re: [PATCH] iommu/vt-d: fix race between free_irte() and get_irte()

Greg Edwards
2014-07-23T14:49:24Z

On Wed, Jul 23, 2014 at 04:40:24PM +0200, Joerg Roedel wrote:
> On Tue, Jul 22, 2014 at 08:27:19AM -0600, Greg Edwards wrote:
>> get_irte() can race with free_irte() and dereference a NULL iommu
>> pointer.
>
> Have you seen any real occurance of this race? Get_irte is called in the
> set_affinity path, how can that race with the irq being freed?

Yes, that's how we hit it. A process was setting the CPU affinity while
QEMU was releasing the IRQ. We have a CI stress test that turned this
up.

Greg