linux-kernel - Re: [PATCH 0/3] mmu notifier contextual informations

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Date:   Tue, 4 Dec 2018 07:35:22 +0000
From:   "Koenig, Christian" <Christian.Koenig@....com>
To:     "jglisse@...hat.com" <jglisse@...hat.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>
CC:     Andrew Morton <akpm@...ux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Matthew Wilcox <mawilcox@...rosoft.com>,
        Ross Zwisler <zwisler@...nel.org>, Jan Kara <jack@...e.cz>,
        Dan Williams <dan.j.williams@...el.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Michal Hocko <mhocko@...nel.org>,
        "Kuehling, Felix" <Felix.Kuehling@....com>,
        Ralph Campbell <rcampbell@...dia.com>,
        John Hubbard <jhubbard@...dia.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-rdma@...r.kernel.org" <linux-rdma@...r.kernel.org>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>
Subject: Re: [PATCH 0/3] mmu notifier contextual informations

Am 03.12.18 um 21:18 schrieb jglisse@...hat.com:
> From: Jérôme Glisse <jglisse@...hat.com>
>
> This patchset add contextual information, why an invalidation is
> happening, to mmu notifier callback. This is necessary for user
> of mmu notifier that wish to maintains their own data structure
> without having to add new fields to struct vm_area_struct (vma).
>
> For instance device can have they own page table that mirror the
> process address space. When a vma is unmap (munmap() syscall) the
> device driver can free the device page table for the range.
>
> Today we do not have any information on why a mmu notifier call
> back is happening and thus device driver have to assume that it
> is always an munmap(). This is inefficient at it means that it
> needs to re-allocate device page table on next page fault and
> rebuild the whole device driver data structure for the range.
>
> Other use case beside munmap() also exist, for instance it is
> pointless for device driver to invalidate the device page table
> when the invalidation is for the soft dirtyness tracking. Or
> device driver can optimize away mprotect() that change the page
> table permission access for the range.
>
> This patchset enable all this optimizations for device driver.
> I do not include any of those in this serie but other patchset
> i am posting will leverage this.
>
>
>  From code point of view the patchset is pretty simple, the first
> two patches consolidate all mmu notifier arguments into a struct
> so that it is easier to add/change arguments. The last patch adds
> the contextual information (munmap, protection, soft dirty, clear,
> ...).

Skimming over it at least the parts I'm familiar with look completely 
sane to me.

Whole series is Acked-by: Christian König <christian.koenig@....com>.

Regards,
Christian.

>
> Cheers,
> Jérôme
>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Matthew Wilcox <mawilcox@...rosoft.com>
> Cc: Ross Zwisler <zwisler@...nel.org>
> Cc: Jan Kara <jack@...e.cz>
> Cc: Dan Williams <dan.j.williams@...el.com>
> Cc: Paolo Bonzini <pbonzini@...hat.com>
> Cc: Radim Krčmář <rkrcmar@...hat.com>
> Cc: Michal Hocko <mhocko@...nel.org>
> Cc: Christian Koenig <christian.koenig@....com>
> Cc: Felix Kuehling <felix.kuehling@....com>
> Cc: Ralph Campbell <rcampbell@...dia.com>
> Cc: John Hubbard <jhubbard@...dia.com>
> Cc: kvm@...r.kernel.org
> Cc: linux-rdma@...r.kernel.org
> Cc: linux-fsdevel@...r.kernel.org
> Cc: dri-devel@...ts.freedesktop.org
>
> Jérôme Glisse (3):
>    mm/mmu_notifier: use structure for invalidate_range_start/end callback
>    mm/mmu_notifier: use structure for invalidate_range_start/end calls
>    mm/mmu_notifier: contextual information for event triggering
>      invalidation
>
>   drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c  |  43 ++++-----
>   drivers/gpu/drm/i915/i915_gem_userptr.c |  14 ++-
>   drivers/gpu/drm/radeon/radeon_mn.c      |  16 ++--
>   drivers/infiniband/core/umem_odp.c      |  20 ++---
>   drivers/infiniband/hw/hfi1/mmu_rb.c     |  13 ++-
>   drivers/misc/mic/scif/scif_dma.c        |  11 +--
>   drivers/misc/sgi-gru/grutlbpurge.c      |  14 ++-
>   drivers/xen/gntdev.c                    |  12 +--
>   fs/dax.c                                |  11 ++-
>   fs/proc/task_mmu.c                      |  10 ++-
>   include/linux/mm.h                      |   4 +-
>   include/linux/mmu_notifier.h            | 106 +++++++++++++++-------
>   kernel/events/uprobes.c                 |  13 +--
>   mm/hmm.c                                |  23 ++---
>   mm/huge_memory.c                        |  58 ++++++------
>   mm/hugetlb.c                            |  63 +++++++------
>   mm/khugepaged.c                         |  13 +--
>   mm/ksm.c                                |  26 +++---
>   mm/madvise.c                            |  22 ++---
>   mm/memory.c                             | 112 ++++++++++++++----------
>   mm/migrate.c                            |  30 ++++---
>   mm/mmu_notifier.c                       |  22 +++--
>   mm/mprotect.c                           |  17 ++--
>   mm/mremap.c                             |  14 +--
>   mm/oom_kill.c                           |  20 +++--
>   mm/rmap.c                               |  34 ++++---
>   virt/kvm/kvm_main.c                     |  14 ++-
>   27 files changed, 421 insertions(+), 334 deletions(-)
>