Hi all, this series removes the offset by one refcount for ZONE_DEVICE pages that are freed back to the driver owning them, which is just device private ones for now, but also the planned device coherent pages and the ehanced p2p ones pending. It does not address the fsdax pages yet, which will be attacked in a follow on series. Note that if we want to get the p2p series rebased on top of this we'll need a git branch for this series. I could offer to host one. A git tree is available here: git://git.infradead.org/users/hch/misc.git pgmap-refcount Gitweb: http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/pgmap-refcount Changes since v1: - add a missing memremap.h include in memcontrol.c - include rebased versions of the device coherent support and device coherent migration support series as well as additional cleanup patches Diffstt: arch/arm64/mm/mmu.c | 1 arch/powerpc/kvm/book3s_hv_uvmem.c | 1 drivers/gpu/drm/amd/amdkfd/kfd_migrate.c | 35 - drivers/gpu/drm/amd/amdkfd/kfd_priv.h | 1 drivers/gpu/drm/drm_cache.c | 2 drivers/gpu/drm/nouveau/nouveau_dmem.c | 3 drivers/gpu/drm/nouveau/nouveau_svm.c | 1 drivers/infiniband/core/rw.c | 1 drivers/nvdimm/pmem.h | 1 drivers/nvme/host/pci.c | 1 drivers/nvme/target/io-cmd-bdev.c | 1 fs/Kconfig | 2 fs/fuse/virtio_fs.c | 1 include/linux/hmm.h | 9 include/linux/memremap.h | 36 + include/linux/migrate.h | 1 include/linux/mm.h | 59 -- lib/test_hmm.c | 353 ++++++++++--- lib/test_hmm_uapi.h | 22 mm/Kconfig | 7 mm/Makefile | 1 mm/gup.c | 127 +++- mm/internal.h | 3 mm/memcontrol.c | 19 mm/memory-failure.c | 8 mm/memremap.c | 75 +- mm/migrate.c | 763 ---------------------------- mm/migrate_device.c | 822 +++++++++++++++++++++++++++++++ mm/rmap.c | 5 mm/swap.c | 49 - tools/testing/selftests/vm/Makefile | 2 tools/testing/selftests/vm/hmm-tests.c | 204 ++++++- tools/testing/selftests/vm/test_hmm.sh | 24 33 files changed, 1552 insertions(+), 1088 deletions(-)