[PATCH v2] x86: Revert E820_PRAM change in e820_end_pfn()

[PATCH v2] x86: Revert E820_PRAM change in e820_end_pfn()

[Toshi Kani]

'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.  Revert the change made to account
E820_PRAM as RAM in e820.c in the commit.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Tested-by: Christoph Hellwig <hch@lst.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)
 {
 	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)

Re: [PATCH v2] x86: Revert E820_PRAM change in e820_end_pfn()

[Boaz Harrosh]

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@plexistor.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@kernel.org>
> Signed-off-by: Toshi Kani <toshi.kani@hp.com>
> Tested-by: Christoph Hellwig <hch@lst.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

Re: [PATCH v2] x86: Revert E820_PRAM change in e820_end_pfn()

[Christoph Hellwig]

On Tue, Apr 07, 2015 at 09:36:37AM +0300, Boaz Harrosh wrote:
> 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

I'd love to resurrect the old "real page backed" pmem support from
the old Intel patches eventually, but with all the arguments on
how we should do I/O on pmem I'd like to keep that a ѕeparate
discussion.  And leaving only fragments of some support in is a bad
idea, so sorry for letting all this slip through..

> > -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

It's a static function, and we have much worse naming sins in public
ones, so I'm not worried about a _ram more or less.  But if people feel
stronly about it I'm fine with adding the _ram.

I feel pretty stronly against adding back a pointless argument, though.

Re: [PATCH v2] x86: Revert E820_PRAM change in e820_end_pfn()

[Toshi Kani]

On Tue, 2015-04-07 at 09:04 +0200, Christoph Hellwig wrote:
> On Tue, Apr 07, 2015 at 09:36:37AM +0300, Boaz Harrosh wrote:
> > 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
> 
> I'd love to resurrect the old "real page backed" pmem support from
> the old Intel patches eventually, but with all the arguments on
> how we should do I/O on pmem I'd like to keep that a ѕeparate
> discussion. And leaving only fragments of some support in is a bad
> idea, 

Agreed -- it should be a separate discussion and we need to get it
straight for 4.1.

> so sorry for letting all this slip through..

No problem.

> > > -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
> 
> It's a static function, and we have much worse naming sins in public
> ones, so I'm not worried about a _ram more or less.  But if people feel
> stronly about it I'm fine with adding the _ram.
> 
> I feel pretty stronly against adding back a pointless argument, though.

We should keep this patch as a revert/fix, and should not combine with
other cleanup.  Adding the _ram, etc. can be done as a separate change.

Thanks,
-Toshi