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. Changes since v17: - typos - ZONE_DEVICE page refcount move put_zone_device_page() Work is still underway to use this feature inside the upstream nouveau driver. It has been tested with closed source driver and test are still underway on top of new kernel. So far we have found no issues. I expect to get a tested-by soon. Also this feature is not only useful for NVidia GPU, i expect AMD GPU will need it too if they want to support some of the new industry API. I also expect some FPGA company to use it and probably other hardware. That being said I don't expect i will ever get a review-by anyone for reasons beyond my control. Many people have read the code and i included their comments each time they had any. So i believe this code had sufficient scrutiny from various people to warrent it being merge. I am willing to face and deal with the fallout but i don't expect any as this is an opt-in code thought i believe all major distribution will enable it in order to support new hardware. I do not wish to compete for the patchset with the highest revision count and i would like a clear cut position on wether it can be merge or not. If not i would like to know why because i am more than willing to address any issues people might have. I just don't want to keep submitting it over and over until i end up in hell. So please consider applying for 4.12 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-v18 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@xxxxxxxxxxxxxxx/msg1304107.html v16 http://www.spinics.net/lists/linux-mm/msg119814.html v17 https://lkml.org/lkml/2017/1/27/847 Jérôme Glisse (16): mm/memory/hotplug: convert device bool to int to allow for more flags v3 mm/put_page: move ref decrement to put_zone_device_page() mm/ZONE_DEVICE/free-page: callback when page is freed v3 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 v4 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 v2 mm/hmm/mirror: device page fault handler mm/hmm/migrate: support un-addressable ZONE_DEVICE page in migration mm/migrate: allow migrate_vma() to alloc new page on empty entry 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 | 23 +- 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/f2fs/data.c | 8 +- fs/f2fs/f2fs.h | 2 +- fs/hugetlbfs/inode.c | 9 +- fs/nfs/internal.h | 5 +- fs/nfs/write.c | 9 +- fs/proc/task_mmu.c | 7 + fs/ubifs/file.c | 8 +- include/linux/balloon_compaction.h | 3 +- include/linux/fs.h | 13 +- include/linux/hmm.h | 468 +++++++++++ include/linux/ioport.h | 1 + include/linux/memory_hotplug.h | 31 +- include/linux/memremap.h | 37 + include/linux/migrate.h | 86 +- include/linux/mm.h | 8 +- include/linux/mm_types.h | 5 + include/linux/swap.h | 18 +- include/linux/swapops.h | 67 ++ kernel/fork.c | 2 + kernel/memremap.c | 34 +- mm/Kconfig | 38 + mm/Makefile | 1 + mm/balloon_compaction.c | 2 +- mm/hmm.c | 1231 ++++++++++++++++++++++++++++ mm/memory.c | 66 +- mm/memory_hotplug.c | 14 +- mm/migrate.c | 786 +++++++++++++++++- mm/mprotect.c | 12 + mm/page_vma_mapped.c | 10 + mm/rmap.c | 25 + mm/zsmalloc.c | 12 +- 42 files changed, 3119 insertions(+), 84 deletions(-) create mode 100644 include/linux/hmm.h create mode 100644 mm/hmm.c -- 2.4.11 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
