This patch series introduces MEMORY_DEVICE_COHERENT, a type of memory owned by a device that can be mapped into CPU page tables like MEMORY_DEVICE_GENERIC and can also be migrated like MEMORY_DEVICE_PRIVATE. With MEMORY_DEVICE_COHERENT, we isolate the new memory type from other subsystems as far as possible, though there are some small changes to other subsystems such as filesystem DAX, to handle the new memory type appropriately. We use ZONE_DEVICE for this instead of NUMA so that the amdgpu allocator can manage it without conflicting with core mm for non-unified memory use cases. How it works: The system BIOS advertises the GPU device memory (aka VRAM) as SPM (special purpose memory) in the UEFI system address map. The amdgpu driver registers the memory with devmap as MEMORY_DEVICE_COHERENT using devm_memremap_pages. The initial user for this hardware page migration capability will be the Frontier supercomputer project. Our nodes in the lab have .5 TB of system memory plus 256 GB of device memory split across 4 GPUs, all in the same coherent address space. Page migration is expected to improve application efficiency significantly. We will report empirical results as they become available. This includes patches originally by Ralph Campbell to change ZONE_DEVICE reference counting as requested in previous reviews of this patch series (see https://patchwork.freedesktop.org/series/90706/). We extended hmm_test to cover migration of MEMORY_DEVICE_COHERENT. This patch set builds on HMM and our SVM memory manager already merged in 5.14. We would like to complete review and merge this migration patchset for 5.16. Alex Sierra (10): mm: add zone device coherent type memory support mm: add device coherent vma selection for memory migration drm/amdkfd: ref count init for device pages drm/amdkfd: add SPM support for SVM drm/amdkfd: coherent type as sys mem on migration to ram lib: test_hmm add ioctl to get zone device type lib: test_hmm add module param for zone device type lib: add support for device coherent type in test_hmm tools: update hmm-test to support device coherent type tools: update test_hmm script to support SP config Ralph Campbell (2): ext4/xfs: add page refcount helper mm: remove extra ZONE_DEVICE struct page refcount arch/powerpc/kvm/book3s_hv_uvmem.c | 2 +- drivers/gpu/drm/amd/amdkfd/kfd_migrate.c | 40 ++-- drivers/gpu/drm/nouveau/nouveau_dmem.c | 2 +- fs/dax.c | 8 +- fs/ext4/inode.c | 5 +- fs/fuse/dax.c | 4 +- fs/xfs/xfs_file.c | 4 +- include/linux/dax.h | 10 + include/linux/memremap.h | 15 +- include/linux/migrate.h | 1 + include/linux/mm.h | 19 +- lib/test_hmm.c | 276 +++++++++++++++++------ lib/test_hmm_uapi.h | 20 +- mm/internal.h | 8 + mm/memcontrol.c | 12 +- mm/memory-failure.c | 6 +- mm/memremap.c | 71 ++---- mm/migrate.c | 33 +-- mm/page_alloc.c | 3 + mm/swap.c | 45 +--- tools/testing/selftests/vm/hmm-tests.c | 137 +++++++++-- tools/testing/selftests/vm/test_hmm.sh | 20 +- 22 files changed, 490 insertions(+), 251 deletions(-) -- 2.32.0
