Re: [PATCH v2 00/20] get_user_pages() for dax mappings

[Logan Gunthorpe <logang@deltatee.com>]

Hi Dan,

We've tested this patch series (as pulled from your git repo) with our 
P2P work and everything is working great. The issues we found in v1 have 
been fixed and we have not found any new ones.

Tested-By: Logan Gunthorpe <logang@deltatee.com>

Thanks,

Logan



On 09/10/15 06:55 PM, Dan Williams wrote:
> Changes since v1 [1]:
> 1/ Rebased on the accepted cleanups to the memremap() api and the NUMA
>     hints for devm allocations. (see libnvdimm-for-next [2]).
>
> 2/ Rebased on DAX fixes from Ross [3], currently in -mm, and Dave [4],
>     applied locally for now.
>
> 3/ Renamed __pfn_t to pfn_t and converted KVM and UM accordingly (Dave
>     Hansen)
>
> 4/ Make pfn-to-pfn_t conversions a nop (binary identical) for typical
>     mapped pfns (Dave Hansen)
>
> 5/ Fixed up the devm_memremap_pages() api to require passing in a
>     percpu_ref object.  Addresses a crash reported-by Logan.
>
> 6/ Moved the back pointer from a page to its hosting 'struct
>     dev_pagemap' to share storage with the 'lru' field rather than
>     'mapping'.  Enables us to revoke mappings at devm_memunmap_page()
>     time and addresses a crash reported-by Logan.
>
> 7/ Rework dax_map_bh() into dax_map_atomic() to avoid proliferating
>     buffer_head usage deeper into the dax implementation.  Also addresses
>     a crash reported by Logan (Dave Chinner)
>
> 8/ Include an initial, only lightly tested, implementation of revoking
>     usages of ZONE_DEVICE pages when the driver disables the pmem device.
>     This coordinates with blk_cleanup_queue() for the pmem gendisk, see
>     patch 19.
>
> 9/ Include a cleaned up version of the vmem_altmap infrastructure
>     allowing the struct page memmap to optionally be allocated from pmem
>     itself.
>
> [1]: https://lists.01.org/pipermail/linux-nvdimm/2015-September/002199.html
> [2]: https://git.kernel.org/cgit/linux/kernel/git/nvdimm/nvdimm.git/log/?h=libnvdimm-for-next
> [3]: https://git.kernel.org/cgit/linux/kernel/git/nvdimm/nvdimm.git/commit/?h=dax-fixes&id=93fdde069dce
> [4]: https://lists.01.org/pipermail/linux-nvdimm/2015-October/002286.html
>
> ---
> To date, we have implemented two I/O usage models for persistent memory,
> PMEM (a persistent "ram disk") and DAX (mmap persistent memory into
> userspace).  This series adds a third, DAX-GUP, that allows DAX mappings
> to be the target of direct-i/o.  It allows userspace to coordinate
> DMA/RDMA from/to persitent memory.
>
> The implementation leverages the ZONE_DEVICE mm-zone that went into
> 4.3-rc1 to flag pages that are owned and dynamically mapped by a device
> driver.  The pmem driver, after mapping a persistent memory range into
> the system memmap via devm_memremap_pages(), arranges for DAX to
> distinguish pfn-only versus page-backed pmem-pfns via flags in the new
> __pfn_t type.  The DAX code, upon seeing a PFN_DEV+PFN_MAP flagged pfn,
> flags the resulting pte(s) inserted into the process page tables with a
> new _PAGE_DEVMAP flag.  Later, when get_user_pages() is walking ptes it
> keys off _PAGE_DEVMAP to pin the device hosting the page range active.
> Finally, get_page() and put_page() are modified to take references
> against the device driver established page mapping.
>
> This series is available via git here:
>
>    git://git.kernel.org/pub/scm/linux/kernel/git/djbw/nvdimm libnvdimm-pending
>
> ---
>
> Dan Williams (20):
>        block: generic request_queue reference counting
>        dax: increase granularity of dax_clear_blocks() operations
>        block, dax: fix lifetime of in-kernel dax mappings with dax_map_atomic()
>        mm: introduce __get_dev_pagemap()
>        x86, mm: introduce vmem_altmap to augment vmemmap_populate()
>        libnvdimm, pfn, pmem: allocate memmap array in persistent memory
>        avr32: convert to asm-generic/memory_model.h
>        hugetlb: fix compile error on tile
>        frv: fix compiler warning from definition of __pmd()
>        um: kill pfn_t
>        kvm: rename pfn_t to kvm_pfn_t
>        mips: fix PAGE_MASK definition
>        mm, dax, pmem: introduce pfn_t
>        mm, dax, gpu: convert vm_insert_mixed to pfn_t, introduce _PAGE_DEVMAP
>        mm, dax: convert vmf_insert_pfn_pmd() to pfn_t
>        list: introduce list_poison() and LIST_POISON3
>        mm, dax, pmem: introduce {get|put}_dev_pagemap() for dax-gup
>        block: notify queue death confirmation
>        mm, pmem: devm_memunmap_pages(), truncate and unmap ZONE_DEVICE pages
>        mm, x86: get_user_pages() for dax mappings
>
>
>   arch/alpha/include/asm/pgtable.h        |    1
>   arch/arm/include/asm/kvm_mmu.h          |    5 -
>   arch/arm/kvm/mmu.c                      |   10 +
>   arch/arm64/include/asm/kvm_mmu.h        |    3
>   arch/avr32/include/asm/page.h           |    8 -
>   arch/frv/include/asm/page.h             |    2
>   arch/ia64/include/asm/pgtable.h         |    1
>   arch/m68k/include/asm/page_mm.h         |    1
>   arch/m68k/include/asm/page_no.h         |    1
>   arch/mips/include/asm/kvm_host.h        |    6 -
>   arch/mips/include/asm/page.h            |    2
>   arch/mips/kvm/emulate.c                 |    2
>   arch/mips/kvm/tlb.c                     |   14 +
>   arch/parisc/include/asm/pgtable.h       |    1
>   arch/powerpc/include/asm/kvm_book3s.h   |    4
>   arch/powerpc/include/asm/kvm_ppc.h      |    2
>   arch/powerpc/include/asm/pgtable.h      |    1
>   arch/powerpc/kvm/book3s.c               |    6 -
>   arch/powerpc/kvm/book3s_32_mmu_host.c   |    2
>   arch/powerpc/kvm/book3s_64_mmu_host.c   |    2
>   arch/powerpc/kvm/e500.h                 |    2
>   arch/powerpc/kvm/e500_mmu_host.c        |    8 -
>   arch/powerpc/kvm/trace_pr.h             |    2
>   arch/powerpc/sysdev/axonram.c           |    8 -
>   arch/sparc/include/asm/pgtable_64.h     |    2
>   arch/tile/include/asm/pgtable.h         |    1
>   arch/um/include/asm/page.h              |    6 -
>   arch/um/include/asm/pgtable-3level.h    |    5 -
>   arch/um/include/asm/pgtable.h           |    2
>   arch/x86/include/asm/pgtable.h          |   24 ++
>   arch/x86/include/asm/pgtable_types.h    |    7 +
>   arch/x86/kvm/iommu.c                    |   11 +
>   arch/x86/kvm/mmu.c                      |   37 ++--
>   arch/x86/kvm/mmu_audit.c                |    2
>   arch/x86/kvm/paging_tmpl.h              |    6 -
>   arch/x86/kvm/vmx.c                      |    2
>   arch/x86/kvm/x86.c                      |    2
>   arch/x86/mm/gup.c                       |   56 +++++-
>   arch/x86/mm/init_64.c                   |   32 +++
>   arch/x86/mm/pat.c                       |    4
>   block/blk-core.c                        |   79 +++++++-
>   block/blk-mq-sysfs.c                    |    6 -
>   block/blk-mq.c                          |   87 +++------
>   block/blk-sysfs.c                       |    3
>   block/blk.h                             |   12 +
>   drivers/block/brd.c                     |    4
>   drivers/gpu/drm/exynos/exynos_drm_gem.c |    3
>   drivers/gpu/drm/gma500/framebuffer.c    |    3
>   drivers/gpu/drm/msm/msm_gem.c           |    3
>   drivers/gpu/drm/omapdrm/omap_gem.c      |    6 -
>   drivers/gpu/drm/ttm/ttm_bo_vm.c         |    3
>   drivers/nvdimm/pfn_devs.c               |    3
>   drivers/nvdimm/pmem.c                   |  128 +++++++++----
>   drivers/s390/block/dcssblk.c            |   10 -
>   fs/block_dev.c                          |    2
>   fs/dax.c                                |  199 +++++++++++++--------
>   include/asm-generic/pgtable.h           |    6 -
>   include/linux/blk-mq.h                  |    1
>   include/linux/blkdev.h                  |   12 +
>   include/linux/huge_mm.h                 |    2
>   include/linux/hugetlb.h                 |    1
>   include/linux/io.h                      |   17 --
>   include/linux/kvm_host.h                |   37 ++--
>   include/linux/kvm_types.h               |    2
>   include/linux/list.h                    |   14 +
>   include/linux/memory_hotplug.h          |    3
>   include/linux/mm.h                      |  300 +++++++++++++++++++++++++++++--
>   include/linux/mm_types.h                |    5 +
>   include/linux/pfn.h                     |    9 +
>   include/linux/poison.h                  |    1
>   kernel/memremap.c                       |  187 +++++++++++++++++++
>   lib/list_debug.c                        |    2
>   mm/gup.c                                |   11 +
>   mm/huge_memory.c                        |   10 +
>   mm/hugetlb.c                            |   18 ++
>   mm/memory.c                             |   17 +-
>   mm/memory_hotplug.c                     |   66 +++++--
>   mm/page_alloc.c                         |   10 +
>   mm/sparse-vmemmap.c                     |   37 ++++
>   mm/sparse.c                             |    8 +
>   mm/swap.c                               |   15 ++
>   virt/kvm/kvm_main.c                     |   47 ++---
>   82 files changed, 1264 insertions(+), 418 deletions(-)
>
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>
>
>

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