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Message-ID: <CAFqt6zbDk7OAdk-WXG50Frppny0DOpdwR1vnTS7pCpjf66j3aQ@mail.gmail.com>
Date: Tue, 9 Apr 2019 11:47:37 +0530
From: Souptick Joarder <jrdr.linux@...il.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
Matthew Wilcox <willy@...radead.org>,
Michal Hocko <mhocko@...e.com>,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Vlastimil Babka <vbabka@...e.cz>,
Rik van Riel <riel@...riel.com>,
Stephen Rothwell <sfr@...b.auug.org.au>,
rppt@...ux.vnet.ibm.com, Peter Zijlstra <peterz@...radead.org>,
Russell King - ARM Linux <linux@...linux.org.uk>,
robin.murphy@....com, iamjoonsoo.kim@....com, treding@...dia.com,
Kees Cook <keescook@...omium.org>,
Marek Szyprowski <m.szyprowski@...sung.com>,
stefanr@...6.in-berlin.de, hjc@...k-chips.com,
Heiko Stuebner <heiko@...ech.de>, airlied@...ux.ie,
oleksandr_andrushchenko@...m.com, joro@...tes.org,
pawel@...iak.com, Kyungmin Park <kyungmin.park@...sung.com>,
mchehab@...nel.org, Boris Ostrovsky <boris.ostrovsky@...cle.com>,
Juergen Gross <jgross@...e.com>
Cc: linux-kernel@...r.kernel.org, Linux-MM <linux-mm@...ck.org>,
linux-arm-kernel@...ts.infradead.org,
linux1394-devel@...ts.sourceforge.net,
dri-devel@...ts.freedesktop.org,
linux-rockchip@...ts.infradead.org, xen-devel@...ts.xen.org,
iommu@...ts.linux-foundation.org, linux-media@...r.kernel.org
Subject: Re: [RESEND PATCH v4 0/9] mm: Use vm_map_pages() and
vm_map_pages_zero() API
Hi Andrew/ Michal,
On Mon, Apr 1, 2019 at 10:56 AM Souptick Joarder <jrdr.linux@...il.com> wrote:
>
> Hi Andrew,
>
> On Tue, Mar 19, 2019 at 7:47 AM Souptick Joarder <jrdr.linux@...il.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 ?
v4 of this series has not received any further comments/ kbuild error
in last 8 weeks (including
the previously posted v4).
Any suggestion, if it safe to take these changes through mm tree ? or any
other tree is preferred ?
>
> >
> > 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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