On Wed, Jun 19, 2019 at 12:53:55AM +0000, Kuehling, Felix wrote: > This code is derived from our old MMU notifier code. Before HMM we used > to register a single MMU notifier per mm_struct and look up virtual > address ranges that had been registered for mirroring via driver API > calls. The idea was to reuse a single MMU notifier for the life time of > the process. It would remain registered until we got a notifier_release. > > hmm_mirror took the place of that when we converted the code to HMM. > > I suppose we could destroy the mirror earlier, when we have no more > registered virtual address ranges, and create a new one if needed later. I didn't write the code, but if you look at hmm_mirror it already is a multiplexer over the mmu notifier, and the intent clearly seems that you register one per range that you want to mirror, and not multiplex it once again. In other words - I think each amdgpu_mn_node should probably have its own hmm_mirror. And while the amdgpu_mn_node objects are currently stored in an interval tree it seems like they are only linearly iterated anyway, so a list actually seems pretty suitable. If not we need to improve the core data structures instead of working around them.
