On 01/27/2017 02:52 PM, Jérôme Glisse wrote:
Cliff note: HMM offers 2 things (each standing on its own). First it allows to use device memory transparently inside any process without any modifications to process program code. Second it allows to mirror process address space on a device.Change since v16: - move HMM unaddressable device memory to its own radix tree and thus find_dev_pagemap() will no longer return HMM dev_pagemap - rename HMM migration helper (drop the prefix) and make them completely independent of HMM Migration can now be use to implement thing like multi-threaded copy or make use of specific memory allocator for destination memory.
We're about to do our usual testing with this, but there will be a brief pause first (the driver API has changed slightly).
thanks john h
Work is under way to use this feature inside nouveau (the upstream open source driver for NVidia GPU) either 411 or 4.12 timeframe. But this patchset have been otherwise tested with the close source driver for NVidia GPU and thus we are confident it works and allow to use the hardware for seamless interaction between CPU and GPU in common address space of a process. I also discussed the features with other company and i am confident it can be use on other, yet, unrelease hardware. Please condiser applying for 4.11 Know issues: Device memory pick some random unuse physical address range. Latter memory hotplug might fails because of this. Intention is to fix this in latter patchset to use physical address above the platform limit thus making sure that no real memory can be hotplug at conflicting address. Patchset overview: Patchset is divided into 3 features that can each be use independently from one another. First is changes to ZONE_DEVICE so we can have struct page for device un-addressable memory (patch 1-4 and 13-14). Second is process address space mirroring (patch 8 to 11), this allow to snapshot CPU page table and to keep the device page table synchronize with the CPU one. Last is a new page migration helper which allow migration for range of virtual address using hardware copy engine (patch 5-7 for new migrate function and 12 for migration of un-addressable memory). Future plan: In this patchset i restricted myself to set of core features what is missing: - force read only on CPU for memory duplication and GPU atomic - changes to mmu_notifier for optimization purposes - migration of file back page to device memory I plan to submit a couple more patchset to implement those features once core HMM is upstream. Git tree: https://cgit.freedesktop.org/~glisse/linux/log/?h=hmm-v17 Previous patchset posting : v1 http://lwn.net/Articles/597289/ v2 https://lkml.org/lkml/2014/6/12/559 v3 https://lkml.org/lkml/2014/6/13/633 v4 https://lkml.org/lkml/2014/8/29/423 v5 https://lkml.org/lkml/2014/11/3/759 v6 http://lwn.net/Articles/619737/ v7 http://lwn.net/Articles/627316/ v8 https://lwn.net/Articles/645515/ v9 https://lwn.net/Articles/651553/ v10 https://lwn.net/Articles/654430/ v11 http://www.gossamer-threads.com/lists/linux/kernel/2286424 v12 http://www.kernelhub.org/?msg=972982&p=2 v13 https://lwn.net/Articles/706856/ v14 https://lkml.org/lkml/2016/12/8/344 v15 http://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1304107.html v16 http://www.spinics.net/lists/linux-mm/msg119814.html Jérôme Glisse (14): mm/memory/hotplug: convert device bool to int to allow for more flags v2 mm/ZONE_DEVICE/free-page: callback when page is freed v2 mm/ZONE_DEVICE/unaddressable: add support for un-addressable device memory v3 mm/ZONE_DEVICE/x86: add support for un-addressable device memory mm/migrate: add new boolean copy flag to migratepage() callback mm/migrate: new memory migration helper for use with device memory v3 mm/migrate: migrate_vma() unmap page from vma while collecting pages mm/hmm: heterogeneous memory management (HMM for short) mm/hmm/mirror: mirror process address space on device with HMM helpers mm/hmm/mirror: helper to snapshot CPU page table mm/hmm/mirror: device page fault handler mm/hmm/migrate: support un-addressable ZONE_DEVICE page in migration mm/hmm/devmem: device memory hotplug using ZONE_DEVICE mm/hmm/devmem: dummy HMM device for ZONE_DEVICE memory v2 MAINTAINERS | 7 + arch/ia64/mm/init.c | 23 +- arch/powerpc/mm/mem.c | 22 +- arch/s390/mm/init.c | 10 +- arch/sh/mm/init.c | 22 +- arch/tile/mm/init.c | 10 +- arch/x86/mm/init_32.c | 23 +- arch/x86/mm/init_64.c | 41 +- drivers/staging/lustre/lustre/llite/rw26.c | 8 +- fs/aio.c | 7 +- fs/btrfs/disk-io.c | 11 +- fs/hugetlbfs/inode.c | 9 +- fs/nfs/internal.h | 5 +- fs/nfs/write.c | 9 +- fs/proc/task_mmu.c | 10 +- fs/ubifs/file.c | 8 +- include/linux/balloon_compaction.h | 3 +- include/linux/fs.h | 13 +- include/linux/hmm.h | 464 +++++++++++ include/linux/ioport.h | 1 + include/linux/memory_hotplug.h | 31 +- include/linux/memremap.h | 39 +- include/linux/migrate.h | 83 +- include/linux/mm_types.h | 5 + include/linux/swap.h | 18 +- include/linux/swapops.h | 67 ++ kernel/fork.c | 2 + kernel/memremap.c | 31 +- mm/Kconfig | 38 + mm/Makefile | 1 + mm/balloon_compaction.c | 2 +- mm/hmm.c | 1235 ++++++++++++++++++++++++++++ mm/memory.c | 64 +- mm/memory_hotplug.c | 14 +- mm/migrate.c | 659 ++++++++++++++- mm/mprotect.c | 12 + mm/rmap.c | 47 ++ mm/zsmalloc.c | 12 +- 38 files changed, 2986 insertions(+), 80 deletions(-) create mode 100644 include/linux/hmm.h create mode 100644 mm/hmm.c -- 2.4.3
