linux-kernel - Re: [PATCH v2] x86: Revert E820_PRAM change in e820_end

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Date:	Tue, 07 Apr 2015 09:36:37 +0300
From:	Boaz Harrosh <boaz@...xistor.com>
To:	Toshi Kani <toshi.kani@...com>, mingo@...hat.com, hpa@...or.com,
	tglx@...utronix.de
CC:	linux-nvdimm@...1.01.org, linux-fsdevel@...r.kernel.org,
	x86@...nel.org, linux-kernel@...r.kernel.org, hch@....de,
	Yinghai Lu <yinghai@...nel.org>
Subject: Re: [PATCH v2] x86: Revert E820_PRAM change in e820_end_pfn()

On 04/06/2015 10:00 PM, Toshi Kani wrote:
> 'Commit ec776ef6bbe17 ("x86/mm: Add support for the non-standard
> protected e820 type")' added E820_PRAM ranges, which do not have
> have struct-page.  Therefore, there is no need to update max_pfn
> to cover the E820_PRAM ranges.  

But E820_PRAM ranges will have the possibility for struct-page.

That said I have tested with this patch +  struct-page and

Tested-by: Boaz Harrosh <boaz@...xistor.com>

Comments below ...

> Revert the change made to account
> E820_PRAM as RAM in e820.c in the commit.
> 
> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> Signed-off-by: Toshi Kani <toshi.kani@...com>
> Tested-by: Christoph Hellwig <hch@....de>
> ---
> The patch is based on the tip branch.
> ---
>  arch/x86/kernel/e820.c |   12 ++++--------
>  1 file changed, 4 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
> index e2ce85d..e09a346 100644
> --- a/arch/x86/kernel/e820.c
> +++ b/arch/x86/kernel/e820.c
> @@ -752,7 +752,7 @@ u64 __init early_reserve_e820(u64 size, u64 align)
>  /*
>   * Find the highest page frame number we have available
>   */
> -static unsigned long __init e820_end_pfn(unsigned long limit_pfn)
> +static unsigned long __init e820_end_pfn(unsigned long limit_pfn, unsigned type)

Why don't you rename it to say e820_max_ram_pfn or something with ram
as you noted, and drop the @type. As Christoph said it is very ugly. You do not
put an extra parameter because of a bad name?

Anyway you are changing all call sites so it will not even be a bigger
change

>  {
>  	int i;
>  	unsigned long last_pfn = 0;
> @@ -763,11 +763,7 @@ static unsigned long __init e820_end_pfn(unsigned long limit_pfn)
>  		unsigned long start_pfn;
>  		unsigned long end_pfn;
>  
> -		/*
> -		 * Persistent memory is accounted as ram for purposes of
> -		 * establishing max_pfn and mem_map.
> -		 */
> -		if (ei->type != E820_RAM && ei->type != E820_PRAM)
> +		if (ei->type != type)
>  			continue;
>  
>  		start_pfn = ei->addr >> PAGE_SHIFT;
> @@ -792,12 +788,12 @@ static unsigned long __init e820_end_pfn(unsigned long limit_pfn)
>  }
>  unsigned long __init e820_end_of_ram_pfn(void)
>  {
> -	return e820_end_pfn(MAX_ARCH_PFN);
> +	return e820_end_pfn(MAX_ARCH_PFN, E820_RAM);
>  }
>  
>  unsigned long __init e820_end_of_low_ram_pfn(void)
>  {
> -	return e820_end_pfn(1UL << (32-PAGE_SHIFT));
> +	return e820_end_pfn(1UL<<(32 - PAGE_SHIFT), E820_RAM);
>  }
>  
>  static void early_panic(char *msg)
> 

Thanks
Boaz

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