[PATCH 1/1] ppc64: iommu vmerge fix

[Sonny Rao]

On Wed, Aug 17, 2005 at 04:05:37PM -0500, Olof Johansson wrote:
> On Wed, Aug 17, 2005 at 03:44:02PM -0500, brking at us.ibm.com wrote:
> 
> > The patch below fixes a bug in the PPC64 iommu vmerge code
> > which results in the potential for iommu_unmap_sg to go off
> > unmapping more than it should. This was found on a test system
> > which resulted in PCI bus errors due to PCI memory being
> > unmapped while DMAs were still in progress.
> 
> Good catch!
> 
> What baffles me a bit is why we haven't seen this until now. If we
> really do merge entries then we would have been freeing entries that we
> shouldn't have freed quite often, and we should have popped the test in
> __iommu_free() at least some of the time.

IIRC, merging isn't turned on by default anywhere, is it?

Sonny