linux-kernel - Re: [PATCH 02/14] MIPS: memblock: Surely map BSS kernel memory section

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Message-ID: <3fbb8850-bf34-d698-299a-f1cd62d063ae@mips.com>
Date:   Mon, 22 Jan 2018 16:35:26 +0000
From:   Matt Redfearn <matt.redfearn@...s.com>
To:     Serge Semin <fancer.lancer@...il.com>, <ralf@...ux-mips.org>,
        <miodrag.dinic@...s.com>, <jhogan@...nel.org>,
        <goran.ferenc@...s.com>, <david.daney@...ium.com>,
        <paul.gortmaker@...driver.com>, <paul.burton@...s.com>,
        <alex.belits@...ium.com>, <Steven.Hill@...ium.com>
CC:     <alexander.sverdlin@...ia.com>, <kumba@...too.org>,
        <marcin.nowakowski@...s.com>, <James.hogan@...s.com>,
        <Peter.Wotton@...s.com>, <Sergey.Semin@...latforms.ru>,
        <linux-mips@...ux-mips.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 02/14] MIPS: memblock: Surely map BSS kernel memory
 section

Hi Serge,

On 17/01/18 22:23, Serge Semin wrote:
> The current MIPS code makes sure the kernel code/data/init
> sections are in the maps, but BSS should also be there.

Quite right - it should. But this was protected against by reserving all 
bootmem up to the _end symbol here:
http://elixir.free-electrons.com/linux/v4.15-rc8/source/arch/mips/kernel/setup.c#L388
Which you remove in the next patch in this series. I'm not sure it is 
worth disentangling the reserved_end stuff from the next patch to make 
this into a single logical change of reserving just .bss rather than 
everything below _end.

Reviewed-by: Matt Redfearn <matt.redfearn@...s.com>

Thanks,
Matt

> 
> Signed-off-by: Serge Semin <fancer.lancer@...il.com>
> ---
>   arch/mips/kernel/setup.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
> index 76e9e2075..0d21c9e04 100644
> --- a/arch/mips/kernel/setup.c
> +++ b/arch/mips/kernel/setup.c
> @@ -845,6 +845,9 @@ static void __init arch_mem_init(char **cmdline_p)
>   	arch_mem_addpart(PFN_UP(__pa_symbol(&__init_begin)) << PAGE_SHIFT,
>   			 PFN_DOWN(__pa_symbol(&__init_end)) << PAGE_SHIFT,
>   			 BOOT_MEM_INIT_RAM);
> +	arch_mem_addpart(PFN_DOWN(__pa_symbol(&__bss_start)) << PAGE_SHIFT,
> +			 PFN_UP(__pa_symbol(&__bss_stop)) << PAGE_SHIFT,
> +			 BOOT_MEM_RAM);
>   
>   	pr_info("Determined physical RAM map:\n");
>   	print_memory_map();
>