On Fri, Sep 04, 2020 at 02:31:11PM +0300, Adalbert Lazăr wrote: > VMAs obtained by mmap()ing memory access fds mirror the contents of the remote > process address space within the specified range. Pages are installed in the > current process page tables at fault time and removed by the mmu_interval_notifier > invalidate callbck. No further memory management is involved. > On attempts to access a hole, or if a mapping was removed by PIDFD_MEM_UNMAP, > or if the remote process address space was reaped by OOM, the remote mapping > fault handler returns VM_FAULT_SIGBUS. I still think anything along these lines needs to meet the XPMEM use cases as well, we have to have more general solutions for such MM stuff: https://gitlab.com/hjelmn/xpmem However, I think this fundamentally falls into some of the same bad direction as xpmem. I would much rather see this design copy & clone the VMA's than try to mirror the PTEs inside the VMAs from the remote into a single giant VMA and somehow split/mirror the VMA ops. This is just too weird and fragile to be maintaible over a long term. For instance, one of the major bugs in things like xpmem was that they are incompatible with get_user_pages(), largely because of this issue. I feel like I said this already.. Jason
