linux-kernel - Re: [PATCHv3 2/3] mm: vmalloc: add VM_DMA flag to indicate areas used by dma-mapping framework

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Message-ID: <4FE2DCE7.80102@kernel.org>
Date:	Thu, 21 Jun 2012 17:35:51 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Marek Szyprowski <m.szyprowski@...sung.com>
CC:	linux-arm-kernel@...ts.infradead.org,
	linaro-mm-sig@...ts.linaro.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Arnd Bergmann <arnd@...db.de>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Chunsang Jeong <chunsang.jeong@...aro.org>,
	Krishna Reddy <vdumpa@...dia.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Hiroshi Doyu <hdoyu@...dia.com>,
	Subash Patel <subashrp@...il.com>,
	KOSAKI Motohiro <kosaki.motohiro@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCHv3 2/3] mm: vmalloc: add VM_DMA flag to indicate areas
 used by dma-mapping framework

Hi Marek,

On 06/13/2012 08:01 PM, Marek Szyprowski wrote:

> Add new type of vm_area intented to be used for mappings created by
> dma-mapping framework.
> 
> Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
> Reviewed-by: Kyungmin Park <kyungmin.park@...sung.com>
> ---
>  include/linux/vmalloc.h |    1 +
>  mm/vmalloc.c            |    3 +++
>  2 files changed, 4 insertions(+), 0 deletions(-)
> 
> diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
> index 2e28f4d..e725b7b 100644
> --- a/include/linux/vmalloc.h
> +++ b/include/linux/vmalloc.h
> @@ -14,6 +14,7 @@ struct vm_area_struct;		/* vma defining user mapping in mm_types.h */
>  #define VM_USERMAP	0x00000008	/* suitable for remap_vmalloc_range */
>  #define VM_VPAGES	0x00000010	/* buffer for pages was vmalloc'ed */
>  #define VM_UNLIST	0x00000020	/* vm_struct is not listed in vmlist */
> +#define VM_DMA		0x00000040	/* used by dma-mapping framework */
>  /* bits [20..32] reserved for arch specific ioremap internals */
>  
>  /*
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 11308f0..e04d59b 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -2575,6 +2575,9 @@ static int s_show(struct seq_file *m, void *p)
>  	if (v->flags & VM_IOREMAP)
>  		seq_printf(m, " ioremap");
>  
> +	if (v->flags & VM_DMA)
> +		seq_printf(m, " dma");
> +
>  	if (v->flags & VM_ALLOC)
>  		seq_printf(m, " vmalloc");
>  


I still don't make sure that we should add new type for only ARM arch.
I remember you said "It would be used for other architectures once we add" and 
Paul said he has a plan for SH. So at least, you should add such comment in changelog
for persuading grumpy maintainers. :)

Frankly speaking, I could add my Reviewed-by but I think it wouldn't carry much weight
because code is very tiny so you need Acked-by rather than Reviewed-by.
IMHO, This problem is the thing only maintainer should decide.
So I will toss the decision to akpm. Ccing akpm.(Ccing KOSAKI because he had a concern about this).

If anyone have a question to me, I'm Acked-by iff other architecture will use it.
-- 
Kind regards,
Minchan Kim
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