linux-kernel - Re: [PATCH v3 -next 0/9] CMA: generalize CMA reserved area management code

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Message-id: <539EB4C7.3080106@samsung.com>
Date:	Mon, 16 Jun 2014 11:11:35 +0200
From:	Marek Szyprowski <m.szyprowski@...sung.com>
To:	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
	Michal Nazarewicz <mina86@...a86.com>
Cc:	Minchan Kim <minchan@...nel.org>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Gleb Natapov <gleb@...nel.org>, Alexander Graf <agraf@...e.de>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	kvm@...r.kernel.org, kvm-ppc@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org,
	Zhang Yanfei <zhangyanfei@...fujitsu.com>
Subject: Re: [PATCH v3 -next 0/9] CMA: generalize CMA reserved area management
 code

Hello,

On 2014-06-16 07:40, Joonsoo Kim wrote:
> Currently, there are two users on CMA functionality, one is the DMA
> subsystem and the other is the KVM on powerpc. They have their own code
> to manage CMA reserved area even if they looks really similar.
> >From my guess, it is caused by some needs on bitmap management. Kvm side
> wants to maintain bitmap not for 1 page, but for more size. Eventually it
> use bitmap where one bit represents 64 pages.
>
> When I implement CMA related patches, I should change those two places
> to apply my change and it seem to be painful to me. I want to change
> this situation and reduce future code management overhead through
> this patch.
>
> This change could also help developer who want to use CMA in their
> new feature development, since they can use CMA easily without
> copying & pasting this reserved area management code.
>
> v3:
>    - Simplify old patch 1(log format fix) and move it to the end of patchset.
>    - Patch 2: Pass aligned base and size to dma_contiguous_early_fixup()
>    - Patch 5: Add some accessor functions to pass aligned base and size to
>    dma_contiguous_early_fixup() function
>    - Patch 5: Move MAX_CMA_AREAS definition to cma.h
>    - Patch 6: Add CMA region zeroing to PPC KVM's CMA alloc function
>    - Patch 8: put 'base' ahead of 'size' in cma_declare_contiguous()
>    - Remaining minor fixes are noted in commit description of each one
>
> v2:
>    - Although this patchset looks very different with v1, the end result,
>    that is, mm/cma.c is same with v1's one. So I carry Ack to patch 6-7.
>
> This patchset is based on linux-next 20140610.

Thanks for taking care of this. I will test it with my setup and if
everything goes well, I will take it to my -next tree. If any branch
is required for anyone to continue his works on top of those patches,
let me know, I will also prepare it.

> Patch 1-4 prepare some features to cover PPC KVM's requirements.
> Patch 5-6 generalize CMA reserved area management code and change users
> to use it.
> Patch 7-9 clean-up minor things.
>
> Joonsoo Kim (9):
>    DMA, CMA: fix possible memory leak
>    DMA, CMA: separate core CMA management codes from DMA APIs
>    DMA, CMA: support alignment constraint on CMA region
>    DMA, CMA: support arbitrary bitmap granularity
>    CMA: generalize CMA reserved area management functionality
>    PPC, KVM, CMA: use general CMA reserved area management framework
>    mm, CMA: clean-up CMA allocation error path
>    mm, CMA: change cma_declare_contiguous() to obey coding convention
>    mm, CMA: clean-up log message
>
>   arch/arm/mm/dma-mapping.c            |    1 +
>   arch/powerpc/kvm/book3s_64_mmu_hv.c  |    4 +-
>   arch/powerpc/kvm/book3s_hv_builtin.c |   19 +-
>   arch/powerpc/kvm/book3s_hv_cma.c     |  240 ------------------------
>   arch/powerpc/kvm/book3s_hv_cma.h     |   27 ---
>   drivers/base/Kconfig                 |   10 -
>   drivers/base/dma-contiguous.c        |  210 ++-------------------
>   include/linux/cma.h                  |   21 +++
>   include/linux/dma-contiguous.h       |   11 +-
>   mm/Kconfig                           |   11 ++
>   mm/Makefile                          |    1 +
>   mm/cma.c                             |  335 ++++++++++++++++++++++++++++++++++
>   12 files changed, 397 insertions(+), 493 deletions(-)
>   delete mode 100644 arch/powerpc/kvm/book3s_hv_cma.c
>   delete mode 100644 arch/powerpc/kvm/book3s_hv_cma.h
>   create mode 100644 include/linux/cma.h
>   create mode 100644 mm/cma.c
>

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland

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