linux-kernel - Re: [RFC PATCH] arm: dma-mapping: fallback allocation for cma failure

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <537BE7CA.4030706@lge.com>
Date:	Wed, 21 May 2014 08:39:54 +0900
From:	Gioh Kim <gioh.kim@....com>
To:	Joonsoo Kim <iamjoonsoo.kim@....com>
CC:	Marek Szyprowski <m.szyprowski@...sung.com>,
	Michal Nazarewicz <mina86@...a86.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Heesub Shin <heesub.shin@...sung.com>,
	Mel Gorman <mgorman@...e.de>,
	Johannes Weiner <hannes@...xchg.org>,
	이건호 <gunho.lee@....com>
Subject: Re: [RFC PATCH] arm: dma-mapping: fallback allocation for cma failure

2014-05-20 오후 5:32, Joonsoo Kim 쓴 글:
> On Tue, May 20, 2014 at 04:05:52PM +0900, Gioh Kim wrote:
>> That case, device-specific coherent memory allocation, is handled at dma_alloc_coherent in arm_dma_alloc.
>> __dma_alloc handles only general coherent memory allocation.
>>
>> I'm sorry missing mention about it.
>>
>
> Hello,
>
> AFAIK, *coherent* memory allocation is different with *contiguous* memory
> allocation(CMA). So we need to handle the case I mentioned.

Yes, I confused the coherent memory aand contiguous memory. It's my mistake.

So I checked dma_alloc_from_contiguous and found dev_get_cma_area function.
The dev_get_cma_area returns device-specific cma if it exists or default global-cma.
I think __alloc_from_contiguous doesn't distinguish device-specific cma area and global cma.
The purpose of __alloc_from_contiguous is allocation of contiguous memory from any cma area, not device-specific area.

If my assumption is right, __alloc_from_contiguous can be replaced with __alloc_remap_buffer without checking device-specific cma area.

What do you think about it?

>
> Thanks.
>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/