[HMM v17 00/14] HMM (Heterogeneous Memory Management) v17

[JÃrÃme Glisse]

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.

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@xxxxxxxxxxxxxxx/msg1304107.html
    v16 http://www.spinics.net/lists/linux-mm/msg119814.html

JÃrÃme 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

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2.4.3