linux-kernel - Re: [PATCH] of: alloc anywhere from memblock if range not specified

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Date:   Tue, 10 Jan 2017 11:49:03 -0800
From:   Laura Abbott <labbott@...hat.com>
To:     Leonard Crestez <cdleonard@...il.com>,
        Vinayak Menon <vinmenon@...eaurora.org>
Cc:     devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, robh+dt@...nel.org,
        frowand.list@...il.com, m.szyprowski@...sung.com,
        vinayakm.list@...il.com,
        Octavian Purdila <octavian.purdila@....com>
Subject: Re: [PATCH] of: alloc anywhere from memblock if range not specified

On 01/10/2017 08:16 AM, Leonard Crestez wrote:
> Hello,
> 
> I have some trouble with this patch.
> 
> It seems the intention is to allow CMA to be placed in highmem. If the CMA area is
> larger than highmem and no alloc-ranges is specified (just a size) it is possible
> to end up allocating a area that spans from multiple zones. This later breaks
> checks in cma_activate_area and makes most dma allocations fail.
> 
> Am I missing something or this a bug?
> 

This has been discussed in previous threads

https://marc.info/?l=linux-kernel&m=147990760506179&w=2
https://marc.info/?l=linux-kernel&m=147928325113103&w=2

I haven't seen any follow up since then though.

> On Mon, Feb 22, 2016 at 3:45 PM, Vinayak Menon <vinmenon@...eaurora.org> wrote:
>>
>> early_init_dt_alloc_reserved_memory_arch passes end as 0 to
>> __memblock_alloc_base, when limits are not specified. But
>> __memblock_alloc_base takes end value of 0 as MEMBLOCK_ALLOC_ACCESSIBLE
>> and limits the end to memblock.current_limit. This results in regions
>> never being placed in HIGHMEM area, for e.g. CMA.
>> Let __memblock_alloc_base allocate from anywhere in memory if limits are
>> not specified.
>>
>> Acked-by: Marek Szyprowski <m.szyprowski@...sung.com>
>> Signed-off-by: Vinayak Menon <vinmenon@...eaurora.org>
>> ---
>>  drivers/of/of_reserved_mem.c | 4 +++-
>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
>> index 1a3556a..ed01c01 100644
>> --- a/drivers/of/of_reserved_mem.c
>> +++ b/drivers/of/of_reserved_mem.c
>> @@ -32,11 +32,13 @@ int __init __weak early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,
>>         phys_addr_t align, phys_addr_t start, phys_addr_t end, bool nomap,
>>         phys_addr_t *res_base)
>>  {
>> +       phys_addr_t base;
>>         /*
>>          * We use __memblock_alloc_base() because memblock_alloc_base()
>>          * panic()s on allocation failure.
>>          */
>> -       phys_addr_t base = __memblock_alloc_base(size, align, end);
>> +       end = !end ? MEMBLOCK_ALLOC_ANYWHERE : end;
>> +       base = __memblock_alloc_base(size, align, end);
>>         if (!base)
>>                 return -ENOMEM;
>>
>> -- 
>> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a
>> member of the Code Aurora Forum, hosted by The Linux Foundation
>>
> -- 
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