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From:   Souptick Joarder <jrdr.linux@gmail.com>
Date:   Thu, 17 Jan 2019 17:09:43 +0530
Message-ID: <CAFqt6zYxCxzGjv3ea+dYQHcmt2P849ZgaVSH=b05m9P4=MTBEA@mail.gmail.com>
Subject: Re: [PATCH 0/9] Use vm_insert_range and vm_insert_range_buggy
To:     Andrew Morton <akpm@linux-foundation.org>,
        Matthew Wilcox <willy@infradead.org>,
        Michal Hocko <mhocko@suse.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        vbabka@suse.cz, Rik van Riel <riel@surriel.com>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        rppt@linux.vnet.ibm.com, Peter Zijlstra <peterz@infradead.org>,
        Russell King - ARM Linux <linux@armlinux.org.uk>,
        robin.murphy@arm.com, iamjoonsoo.kim@lge.com, treding@nvidia.com,
        Kees Cook <keescook@chromium.org>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        stefanr@s5r6.in-berlin.de, hjc@rock-chips.com,
        Heiko Stuebner <heiko@sntech.de>, airlied@linux.ie,
        oleksandr_andrushchenko@epam.com, joro@8bytes.org,
        pawel@osciak.com, Kyungmin Park <kyungmin.park@samsung.com>,
        mchehab@kernel.org, Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        Juergen Gross <jgross@suse.com>
Cc:     linux-kernel@vger.kernel.org, Linux-MM <linux-mm@kvack.org>,
        linux-arm-kernel@lists.infradead.org,
        linux1394-devel@lists.sourceforge.net,
        dri-devel@lists.freedesktop.org,
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On Fri, Jan 11, 2019 at 8:31 PM 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_insert_range() is the API which could be used to mapped
> kernel memory/pages in drivers which has considered vm_pgoff
>
> vm_insert_range_buggy() 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_insert_range_buggy() to behave according to the normal vm_pgoff
> offsetting simply by removing the _buggy suffix on the function
> name and if that causes regressions, it gives us an easy way to revert.
>
> There is an existing bug in [7/9], where user passed length is not
> verified against object_count. For any value of length > object_count
> it will end up overrun page array which could lead to a potential bug.
> This is fixed as part of these conversion.
>
> Souptick Joarder (9):
>   mm: Introduce new vm_insert_range and vm_insert_range_buggy API
>   arch/arm/mm/dma-mapping.c: Convert to use vm_insert_range
>   drivers/firewire/core-iso.c: Convert to use vm_insert_range_buggy
>   drm/rockchip/rockchip_drm_gem.c: Convert to use vm_insert_range
>   drm/xen/xen_drm_front_gem.c: Convert to use vm_insert_range
>   iommu/dma-iommu.c: Convert to use vm_insert_range
>   videobuf2/videobuf2-dma-sg.c: Convert to use vm_insert_range_buggy
>   xen/gntdev.c: Convert to use vm_insert_range
>   xen/privcmd-buf.c: Convert to use vm_insert_range_buggy

Any further comment on these patches ?

>
>  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-dma-sg.c | 22 ++----
>  drivers/xen/gntdev.c                              | 16 ++---
>  drivers/xen/privcmd-buf.c                         |  8 +--
>  include/linux/mm.h                                |  4 ++
>  mm/memory.c                                       | 81 +++++++++++++++++++++++
>  mm/nommu.c                                        | 14 ++++
>  11 files changed, 129 insertions(+), 100 deletions(-)
>
> --
> 1.9.1
>