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

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Message-ID: <717b117d-9b8b-d4e9-6135-3c52afd635c8@gmail.com>
Date:   Tue, 10 Jan 2017 18:16:46 +0200
From:   Leonard Crestez <cdleonard@...il.com>
To:     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, grant.likely@...aro.org,
        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

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?

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
>