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SubjectRe: [RESEND PATCH v4 0/9] mm: Use vm_map_pages() and vm_map_pages_zero() API
Hi Andrew,

On Tue, Mar 19, 2019 at 7:47 AM Souptick Joarder <jrdr.linux@gmail.com> wrote:
>
> Previouly drivers have their own way of mapping range of
> kernel pages/memory into user vma and this was done by
> invoking vm_insert_page() within a loop.
>
> As this pattern is common across different drivers, it can
> be generalized by creating new functions and use it across
> the drivers.
>
> vm_map_pages() is the API which could be used to map
> kernel memory/pages in drivers which has considered vm_pgoff.
>
> vm_map_pages_zero() is the API which could be used to map
> range of kernel memory/pages in drivers which has not considered
> vm_pgoff. vm_pgoff is passed default as 0 for those drivers.
>
> We _could_ then at a later "fix" these drivers which are using
> vm_map_pages_zero() to behave according to the normal vm_pgoff
> offsetting simply by removing the _zero suffix on the function
> name and if that causes regressions, it gives us an easy way to revert.
>
> Tested on Rockchip hardware and display is working fine, including talking
> to Lima via prime.
>
> v1 -> v2:
> Few Reviewed-by.
>
> Updated the change log in [8/9]
>
> In [7/9], vm_pgoff is treated in V4L2 API as a 'cookie'
> to select a buffer, not as a in-buffer offset by design
> and it always want to mmap a whole buffer from its beginning.
> Added additional changes after discussing with Marek and
> vm_map_pages() could be used instead of vm_map_pages_zero().
>
> v2 -> v3:
> Corrected the documentation as per review comment.
>
> As suggested in v2, renaming the interfaces to -
> *vm_insert_range() -> vm_map_pages()* and
> *vm_insert_range_buggy() -> vm_map_pages_zero()*.
> As the interface is renamed, modified the code accordingly,
> updated the change logs and modified the subject lines to use the
> new interfaces. There is no other change apart from renaming and
> using the new interface.
>
> Patch[1/9] & [4/9], Tested on Rockchip hardware.
>
> v3 -> v4:
> Fixed build warnings on patch [8/9] reported by kbuild test robot.
>
> Souptick Joarder (9):
> mm: Introduce new vm_map_pages() and vm_map_pages_zero() API
> arm: mm: dma-mapping: Convert to use vm_map_pages()
> drivers/firewire/core-iso.c: Convert to use vm_map_pages_zero()
> drm/rockchip/rockchip_drm_gem.c: Convert to use vm_map_pages()
> drm/xen/xen_drm_front_gem.c: Convert to use vm_map_pages()
> iommu/dma-iommu.c: Convert to use vm_map_pages()
> videobuf2/videobuf2-dma-sg.c: Convert to use vm_map_pages()
> xen/gntdev.c: Convert to use vm_map_pages()
> xen/privcmd-buf.c: Convert to use vm_map_pages_zero()

Is it fine to take these patches into mm tree for regression ?

>
> arch/arm/mm/dma-mapping.c | 22 ++----
> drivers/firewire/core-iso.c | 15 +---
> drivers/gpu/drm/rockchip/rockchip_drm_gem.c | 17 +----
> drivers/gpu/drm/xen/xen_drm_front_gem.c | 18 ++---
> drivers/iommu/dma-iommu.c | 12 +---
> drivers/media/common/videobuf2/videobuf2-core.c | 7 ++
> .../media/common/videobuf2/videobuf2-dma-contig.c | 6 --
> drivers/media/common/videobuf2/videobuf2-dma-sg.c | 22 ++----
> drivers/xen/gntdev.c | 11 ++-
> drivers/xen/privcmd-buf.c | 8 +--
> include/linux/mm.h | 4 ++
> mm/memory.c | 81 ++++++++++++++++++++++
> mm/nommu.c | 14 ++++
> 13 files changed, 134 insertions(+), 103 deletions(-)
>
> --
> 1.9.1
>

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