• Jérôme Glisse's avatar
    mm/mmu_notifier: use structure for invalidate_range_start/end callback · 5d6527a7
    Jérôme Glisse authored
    Patch series "mmu notifier contextual informations", v2.
    This patchset adds 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 enables all this optimizations for device drivers.  I do not
    include any of those in this series but another patchset I am posting will
    leverage this.
    The patchset is pretty simple from a code point of view.  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, ...).
    This patch (of 3):
    To avoid having to change many callback definition everytime we want to
    add a parameter use a structure to group all parameters for the
    mmu_notifier invalidate_range_start/end callback.  No functional changes
    with this patch.
    [akpm@linux-foundation.org: fix drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c kerneldoc]
    Link: http://lkml.kernel.org/r/20181205053628.3210-2-jglisse@redhat.comSigned-off-by: default avatarJérôme Glisse <jglisse@redhat.com>
    Acked-by: default avatarJan Kara <jack@suse.cz>
    Acked-by: Jason Gunthorpe <jgg@mellanox.com>	[infiniband]
    Cc: Matthew Wilcox <mawilcox@microsoft.com>
    Cc: Ross Zwisler <zwisler@kernel.org>
    Cc: Dan Williams <dan.j.williams@intel.com>
    Cc: Paolo Bonzini <pbonzini@redhat.com>
    Cc: Radim Krcmar <rkrcmar@redhat.com>
    Cc: Michal Hocko <mhocko@kernel.org>
    Cc: Christian Koenig <christian.koenig@amd.com>
    Cc: Felix Kuehling <felix.kuehling@amd.com>
    Cc: Ralph Campbell <rcampbell@nvidia.com>
    Cc: John Hubbard <jhubbard@nvidia.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
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