Hey, On Wed, Feb 03, 2016 at 12:40:57AM +0000, David Woodhouse wrote: > There are a few related issues here around Shared Virtual Memory, and > lifetime management of the associated MM, and the proposal discussed at > the Kernel Summit for "off-CPU tasks". > > I've hit a situation with the Intel SVM code in 4.4 where the device > driver binds a PASID, and also has mmap() functionality on the same > file descriptor that the PASID is associated with. > > So on process exit, the MM doesn't die because the PASID binding still > exists. The VMA of the mmap doesn't die because the MM still exists. So > the underlying file remains open because the VMA still exists. And the > PASID binding thus doesn't die because the file is still open. > > I've posted a patch¹ which moves us closer to the amd_iommu_v2 model, > although I'm still *strongly* resisting the temptation to call out into > device driver code from the mmu_notifier's release callback. > > I would like to attend LSF/MM this year so we can continue to work on > those issues — now that we actually have some hardware in the field and > a better idea of how we can build a unified access model for SVM across > the different IOMMU types. That sounds very interesting and I'd like to participate in this discussion. Unfortunatly I can't make it to the mm-sumit this year, so I didn't even apply for an invitation. But if this gets discussed there I am interested in the outcome. I still have a prototype for the off-cpu task concept on my list of thing to implement. The problem is that I can't really test any changes I make because I don't have SVM hardware and on the AMD side the user-space part needed for testing only runs on Ubuntu with some AMD provided kernel :( Joerg -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>