linux-kernel - Re: [PATCH 1/2] m68k: nommu: register start of the memory with memblock

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Date:   Wed, 17 Jun 2020 22:33:48 +1000
From:   Greg Ungerer <gerg@...ux-m68k.org>
To:     Mike Rapoport <rppt@...nel.org>
Cc:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        linux-m68k@...ts.linux-m68k.org, linux-kernel@...r.kernel.org,
        Mike Rapoport <rppt@...ux.ibm.com>
Subject: Re: [PATCH 1/2] m68k: nommu: register start of the memory with
 memblock

Hi Mike,

On 17/6/20 4:53 pm, Mike Rapoport wrote:
> From: Mike Rapoport <rppt@...ux.ibm.com>
> 
> The m68k nommu setup code didn't register the beginning of the physical
> memory with memblock because it was anyway occupied by the kernel. However,
> commit fa3354e4ea39 ("mm: free_area_init: use maximal zone PFNs rather than
> zone sizes") changed zones initialization to use memblock.memory to detect
> the zone extents and this caused inconsistency between zone PFNs and the
> actual PFNs:
> 
> BUG: Bad page state in process swapper  pfn:20165
> page:41fe0ca0 refcount:0 mapcount:1 mapping:00000000 index:0x0 flags: 0x0()
> raw: 00000000 00000100 00000122 00000000 00000000 00000000 00000000 00000000
> page dumped because: nonzero mapcount
> CPU: 0 PID: 1 Comm: swapper Not tainted 5.8.0-rc1-00001-g3a38f8a60c65-dirty #1
> Stack from 404c9ebc:
>          404c9ebc 4029ab28 4029ab28 40088470 41fe0ca0 40299e21 40299df1 404ba2a4
>          00020165 00000000 41fd2c10 402c7ba0 41fd2c04 40088504 41fe0ca0 40299e21
>          00000000 40088a12 41fe0ca0 41fe0ca4 0000020a 00000000 00000001 402ca000
>          00000000 41fe0ca0 41fd2c10 41fd2c10 00000000 00000000 402b2388 00000001
>          400a0934 40091056 404c9f44 404c9f44 40088db4 402c7ba0 00000001 41fd2c04
>          41fe0ca0 41fd2000 41fe0ca0 40089e02 4026ecf4 40089e4e 41fe0ca0 ffffffff
> Call Trace:
>          [<40088470>] 0x40088470
>   [<40088504>] 0x40088504
>   [<40088a12>] 0x40088a12
>   [<402ca000>] 0x402ca000
>   [<400a0934>] 0x400a0934
> 
> Adjust the memory registration with memblock to include the beginning of
> the physical memory and make sure that the area occupied by the kernel is
> marked as reserved.
> 
> Signed-off-by: Mike Rapoport <rppt@...ux.ibm.com>

Acked-by: Greg Ungerer <gerg@...ux-m68k.org>

Regards
Greg



> ---
>   arch/m68k/kernel/setup_no.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/m68k/kernel/setup_no.c b/arch/m68k/kernel/setup_no.c
> index e779b19e0193..f66f4b1d062e 100644
> --- a/arch/m68k/kernel/setup_no.c
> +++ b/arch/m68k/kernel/setup_no.c
> @@ -138,7 +138,8 @@ void __init setup_arch(char **cmdline_p)
>   	pr_debug("MEMORY -> ROMFS=0x%p-0x%06lx MEM=0x%06lx-0x%06lx\n ",
>   		 __bss_stop, memory_start, memory_start, memory_end);
>   
> -	memblock_add(memory_start, memory_end - memory_start);
> +	memblock_add(_rambase, memory_end - _rambase);
> +	memblock_reserve(_rambase, memory_start - _rambase);
>   
>   	/* Keep a copy of command line */
>   	*cmdline_p = &command_line[0];
>