linux-kernel - Re: drm/radeon spamming alloc_contig

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Date:   Fri, 2 Dec 2016 07:36:50 +0100
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Michal Nazarewicz <mina86@...a86.com>,
        Michal Hocko <mhocko@...nel.org>
Cc:     "Robin H. Johnson" <robbat2@...too.org>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        dri-devel@...ts.freedesktop.org, Joonsoo Kim <js1304@...il.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>
Subject: Re: drm/radeon spamming alloc_contig_range: [xxx, yyy) PFNs busy busy

On 12/01/2016 10:02 PM, Michal Nazarewicz wrote:
> On Thu, Dec 01 2016, Michal Hocko wrote:
>> I am not familiar with this code so I cannot really argue but a quick
>> look at rmem_cma_setup doesn't suggest any speicific placing or
>> anything...
>
> early_cma parses ‘cma’ command line argument which can specify where
> exactly the default CMA area is to be located.  Furthermore, CMA areas
> can be assigned per-device (via the Device Tree IIRC).

OK, but the context of this bug report is a generic cma pool and generic 
dma alloc, which tries cma first and then fallback to 
alloc_pages_node(). If a device really requires specific placing as you 
suggest, then it probably uses a different allocation interface, 
otherwise there would be some flag to disallow the alloc_pages_node() 
fallback?