On Mon, 2014-07-07 at 12:11 +0200, joro@xxxxxxxxxx wrote: > On Sun, Jul 06, 2014 at 07:25:18PM +0000, Gabbay, Oded wrote: > > Once we can agree on that, than I think we can agree that kfd and hmm > > can and should be bounded to mm struct and not file descriptors. > > The file descriptor concept is the way it works in the rest of the > kernel. It works for numerous drivers and subsystems (KVM, VFIO, UIO, > ...), when you close a file descriptor handed out from any of those > drivers (already in the kernel) all related resources will be freed. I > don't see a reason why HSA drivers should break these expectations and > be different. > > > Joerg > > As Jerome pointed out, there are a couple of subsystems/drivers who don't rely on file descriptors but on the tear-down of mm struct, e.g. aio, ksm, uprobes, khugepaged So, based on this fact, I don't think that the argument of "The file descriptor concept is the way it works in the rest of the kernel" and only HSA/HMM now wants to change the rules, is a valid argument. Jerome and I are saying that HMM and HSA, respectively, are additional use cases of binding to mm struct. If you don't agree with that, than I would like to hear why, but you can't say that no one else in the kernel needs notification of mm struct tear-down. As for the reasons why HSA drivers should follow aio,ksm,etc. and not other drivers, I will repeat that our ioctls operate on a process context and not on a device context. Moreover, the calling process actually is sometimes not aware on which device it runs! A prime example of why HSA is not a regular device-driver, and operates in context of a process and not a specific device is the fact that in the near future (3-4 months), kfd_open() will actually bind a process address space to a *set* of devices, each of which could have its *own* device driver (eg radeon for the CI device, other amd drivers for future devices). I Assume HMM can be considered in the same way. Oded -- 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>