[PATCH 1/3] mm, nobootmem: fix wrong usage of max_low_pfn

[PATCH 1/3] mm, nobootmem: fix wrong usage of max_low_pfn

[Joonsoo Kim]

max_low_pfn reflect the number of _pages_ in the system,
not the maximum PFN. You can easily find that fact in init_bootmem().
So fix it.

Additionally, if 'start_pfn == end_pfn', we don't need to go futher,
so change range check.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>

diff --git a/mm/nobootmem.c b/mm/nobootmem.c
index 5e07d36..4711e91 100644
--- a/mm/nobootmem.c
+++ b/mm/nobootmem.c
@@ -110,9 +110,9 @@ static unsigned long __init __free_memory_core(phys_addr_t start,
 {
 	unsigned long start_pfn = PFN_UP(start);
 	unsigned long end_pfn = min_t(unsigned long,
-				      PFN_DOWN(end), max_low_pfn);
+				      PFN_DOWN(end), min_low_pfn);
 
-	if (start_pfn > end_pfn)
+	if (start_pfn >= end_pfn)
 		return 0;
 
 	__free_pages_memory(start_pfn, end_pfn);
-- 
1.7.9.5

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[PATCH 2/3] mm, nobootmem: clean-up of free_low_memory_core_early()

[Joonsoo Kim]

Remove unused argument and make function static,
because there is no user outside of nobootmem.c

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>

diff --git a/include/linux/bootmem.h b/include/linux/bootmem.h
index cdc3bab..5f0b0e1 100644
--- a/include/linux/bootmem.h
+++ b/include/linux/bootmem.h
@@ -44,7 +44,6 @@ extern unsigned long init_bootmem_node(pg_data_t *pgdat,
 				       unsigned long endpfn);
 extern unsigned long init_bootmem(unsigned long addr, unsigned long memend);
 
-extern unsigned long free_low_memory_core_early(int nodeid);
 extern unsigned long free_all_bootmem_node(pg_data_t *pgdat);
 extern unsigned long free_all_bootmem(void);
 
diff --git a/mm/nobootmem.c b/mm/nobootmem.c
index 4711e91..589c673 100644
--- a/mm/nobootmem.c
+++ b/mm/nobootmem.c
@@ -120,7 +120,7 @@ static unsigned long __init __free_memory_core(phys_addr_t start,
 	return end_pfn - start_pfn;
 }
 
-unsigned long __init free_low_memory_core_early(int nodeid)
+static unsigned long __init free_low_memory_core_early()
 {
 	unsigned long count = 0;
 	phys_addr_t start, end, size;
@@ -170,7 +170,7 @@ unsigned long __init free_all_bootmem(void)
 	 *  because in some case like Node0 doesn't have RAM installed
 	 *  low ram will be on Node1
 	 */
-	return free_low_memory_core_early(MAX_NUMNODES);
+	return free_low_memory_core_early();
 }
 
 /**
-- 
1.7.9.5

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Re: [PATCH 2/3] mm, nobootmem: clean-up of free_low_memory_core_early()

[Joonsoo Kim]

On Tue, Mar 19, 2013 at 02:16:00PM +0900, Joonsoo Kim wrote:
> Remove unused argument and make function static,
> because there is no user outside of nobootmem.c
> 
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> 
> diff --git a/include/linux/bootmem.h b/include/linux/bootmem.h
> index cdc3bab..5f0b0e1 100644
> --- a/include/linux/bootmem.h
> +++ b/include/linux/bootmem.h
> @@ -44,7 +44,6 @@ extern unsigned long init_bootmem_node(pg_data_t *pgdat,
>  				       unsigned long endpfn);
>  extern unsigned long init_bootmem(unsigned long addr, unsigned long memend);
>  
> -extern unsigned long free_low_memory_core_early(int nodeid);
>  extern unsigned long free_all_bootmem_node(pg_data_t *pgdat);
>  extern unsigned long free_all_bootmem(void);
>  
> diff --git a/mm/nobootmem.c b/mm/nobootmem.c
> index 4711e91..589c673 100644
> --- a/mm/nobootmem.c
> +++ b/mm/nobootmem.c
> @@ -120,7 +120,7 @@ static unsigned long __init __free_memory_core(phys_addr_t start,
>  	return end_pfn - start_pfn;
>  }
>  
> -unsigned long __init free_low_memory_core_early(int nodeid)
> +static unsigned long __init free_low_memory_core_early()
>  {
>  	unsigned long count = 0;
>  	phys_addr_t start, end, size;
> @@ -170,7 +170,7 @@ unsigned long __init free_all_bootmem(void)
>  	 *  because in some case like Node0 doesn't have RAM installed
>  	 *  low ram will be on Node1
>  	 */
> -	return free_low_memory_core_early(MAX_NUMNODES);
> +	return free_low_memory_core_early();
>  }
>  
>  /**
> -- 
> 1.7.9.5
> 
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Sorry, this patch makes build warning.
Below is fixed version.

-------------------->&------------------------

Re: [PATCH 2/3] mm, nobootmem: clean-up of free_low_memory_core_early()

[Yinghai Lu]

On Mon, Mar 18, 2013 at 10:16 PM, Joonsoo Kim <iamjoonsoo.kim@lge.com> wrote:
> Remove unused argument and make function static,
> because there is no user outside of nobootmem.c
>
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>
> diff --git a/include/linux/bootmem.h b/include/linux/bootmem.h
> index cdc3bab..5f0b0e1 100644
> --- a/include/linux/bootmem.h
> +++ b/include/linux/bootmem.h
> @@ -44,7 +44,6 @@ extern unsigned long init_bootmem_node(pg_data_t *pgdat,
>                                        unsigned long endpfn);
>  extern unsigned long init_bootmem(unsigned long addr, unsigned long memend);
>
> -extern unsigned long free_low_memory_core_early(int nodeid);
>  extern unsigned long free_all_bootmem_node(pg_data_t *pgdat);
>  extern unsigned long free_all_bootmem(void);
>
> diff --git a/mm/nobootmem.c b/mm/nobootmem.c
> index 4711e91..589c673 100644
> --- a/mm/nobootmem.c
> +++ b/mm/nobootmem.c
> @@ -120,7 +120,7 @@ static unsigned long __init __free_memory_core(phys_addr_t start,
>         return end_pfn - start_pfn;
>  }
>
> -unsigned long __init free_low_memory_core_early(int nodeid)
> +static unsigned long __init free_low_memory_core_early()

(void) ?

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Re: [PATCH 2/3] mm, nobootmem: clean-up of free_low_memory_core_early()

[Joonsoo Kim]

On Mon, Mar 18, 2013 at 10:51:43PM -0700, Yinghai Lu wrote:
> On Mon, Mar 18, 2013 at 10:16 PM, Joonsoo Kim <iamjoonsoo.kim@lge.com> wrote:
> > Remove unused argument and make function static,
> > because there is no user outside of nobootmem.c
> >
> > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> >
> > diff --git a/include/linux/bootmem.h b/include/linux/bootmem.h
> > index cdc3bab..5f0b0e1 100644
> > --- a/include/linux/bootmem.h
> > +++ b/include/linux/bootmem.h
> > @@ -44,7 +44,6 @@ extern unsigned long init_bootmem_node(pg_data_t *pgdat,
> >                                        unsigned long endpfn);
> >  extern unsigned long init_bootmem(unsigned long addr, unsigned long memend);
> >
> > -extern unsigned long free_low_memory_core_early(int nodeid);
> >  extern unsigned long free_all_bootmem_node(pg_data_t *pgdat);
> >  extern unsigned long free_all_bootmem(void);
> >
> > diff --git a/mm/nobootmem.c b/mm/nobootmem.c
> > index 4711e91..589c673 100644
> > --- a/mm/nobootmem.c
> > +++ b/mm/nobootmem.c
> > @@ -120,7 +120,7 @@ static unsigned long __init __free_memory_core(phys_addr_t start,
> >         return end_pfn - start_pfn;
> >  }
> >
> > -unsigned long __init free_low_memory_core_early(int nodeid)
> > +static unsigned long __init free_low_memory_core_early()
> 
> (void) ?

Yes, fixed version is already sent.
Thanks.

> 
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[PATCH 3/3] mm, nobootmem: do memset() after memblock_reserve()

[Joonsoo Kim]

Currently, we do memset() before reserving the area.
This may not cause any problem, but it is somewhat weird.
So change execution order.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>

diff --git a/mm/nobootmem.c b/mm/nobootmem.c
index 589c673..f11ec1c 100644
--- a/mm/nobootmem.c
+++ b/mm/nobootmem.c
@@ -46,8 +46,8 @@ static void * __init __alloc_memory_core_early(int nid, u64 size, u64 align,
 		return NULL;
 
 	ptr = phys_to_virt(addr);
-	memset(ptr, 0, size);
 	memblock_reserve(addr, size);
+	memset(ptr, 0, size);
 	/*
 	 * The min_count is set to 0 so that bootmem allocated blocks
 	 * are never reported as leaks.
-- 
1.7.9.5

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Re: [PATCH 3/3] mm, nobootmem: do memset() after memblock_reserve()

[Yinghai Lu]

On Mon, Mar 18, 2013 at 10:16 PM, Joonsoo Kim <iamjoonsoo.kim@lge.com> wrote:
> Currently, we do memset() before reserving the area.
> This may not cause any problem, but it is somewhat weird.
> So change execution order.
>
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>
> diff --git a/mm/nobootmem.c b/mm/nobootmem.c
> index 589c673..f11ec1c 100644
> --- a/mm/nobootmem.c
> +++ b/mm/nobootmem.c
> @@ -46,8 +46,8 @@ static void * __init __alloc_memory_core_early(int nid, u64 size, u64 align,
>                 return NULL;
>
>         ptr = phys_to_virt(addr);
> -       memset(ptr, 0, size);
>         memblock_reserve(addr, size);
> +       memset(ptr, 0, size);

move down ptr = ... too ?

>         /*
>          * The min_count is set to 0 so that bootmem allocated blocks
>          * are never reported as leaks.
> --
> 1.7.9.5
>

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Re: [PATCH 3/3] mm, nobootmem: do memset() after memblock_reserve()

[Joonsoo Kim]

On Mon, Mar 18, 2013 at 10:53:04PM -0700, Yinghai Lu wrote:
> On Mon, Mar 18, 2013 at 10:16 PM, Joonsoo Kim <iamjoonsoo.kim@lge.com> wrote:
> > Currently, we do memset() before reserving the area.
> > This may not cause any problem, but it is somewhat weird.
> > So change execution order.
> >
> > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> >
> > diff --git a/mm/nobootmem.c b/mm/nobootmem.c
> > index 589c673..f11ec1c 100644
> > --- a/mm/nobootmem.c
> > +++ b/mm/nobootmem.c
> > @@ -46,8 +46,8 @@ static void * __init __alloc_memory_core_early(int nid, u64 size, u64 align,
> >                 return NULL;
> >
> >         ptr = phys_to_virt(addr);
> > -       memset(ptr, 0, size);
> >         memblock_reserve(addr, size);
> > +       memset(ptr, 0, size);
> 
> move down ptr = ... too ?
Okay.
I will send v2 soon.

> 
> >         /*
> >          * The min_count is set to 0 so that bootmem allocated blocks
> >          * are never reported as leaks.
> > --
> > 1.7.9.5
> >
> 
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Re: [PATCH 1/3] mm, nobootmem: fix wrong usage of max_low_pfn

[Yinghai Lu]

On Mon, Mar 18, 2013 at 10:15 PM, Joonsoo Kim <iamjoonsoo.kim@lge.com> wrote:
> max_low_pfn reflect the number of _pages_ in the system,
> not the maximum PFN. You can easily find that fact in init_bootmem().
> So fix it.

I'm confused. for x86, we have max_low_pfn defined in ...

#ifdef CONFIG_X86_32
        /* max_low_pfn get updated here */
        find_low_pfn_range();
#else
        num_physpages = max_pfn;

        check_x2apic();

        /* How many end-of-memory variables you have, grandma! */
        /* need this before calling reserve_initrd */
        if (max_pfn > (1UL<<(32 - PAGE_SHIFT)))
                max_low_pfn = e820_end_of_low_ram_pfn();
        else
                max_low_pfn = max_pfn;

and under max_low_pfn is bootmem.

>
> Additionally, if 'start_pfn == end_pfn', we don't need to go futher,
> so change range check.
>
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>
> diff --git a/mm/nobootmem.c b/mm/nobootmem.c
> index 5e07d36..4711e91 100644
> --- a/mm/nobootmem.c
> +++ b/mm/nobootmem.c
> @@ -110,9 +110,9 @@ static unsigned long __init __free_memory_core(phys_addr_t start,
>  {
>         unsigned long start_pfn = PFN_UP(start);
>         unsigned long end_pfn = min_t(unsigned long,
> -                                     PFN_DOWN(end), max_low_pfn);
> +                                     PFN_DOWN(end), min_low_pfn);

what is min_low_pfn ?  is it 0 for x86?

Thanks

Yinghai

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Re: [PATCH 1/3] mm, nobootmem: fix wrong usage of max_low_pfn

[Joonsoo Kim]

On Mon, Mar 18, 2013 at 10:47:41PM -0700, Yinghai Lu wrote:
> On Mon, Mar 18, 2013 at 10:15 PM, Joonsoo Kim <iamjoonsoo.kim@lge.com> wrote:
> > max_low_pfn reflect the number of _pages_ in the system,
> > not the maximum PFN. You can easily find that fact in init_bootmem().
> > So fix it.
> 
> I'm confused. for x86, we have max_low_pfn defined in ...

Below is queote from Russell King in 'https://lkml.org/lkml/2013/3/13/123'


 Now, max_low_pfn is initialized this way:
 
 /**
  * init_bootmem - register boot memory
  * @start: pfn where the bitmap is to be placed
  * @pages: number of available physical pages
  *
  * Returns the number of bytes needed to hold the bitmap.
  */
 unsigned long __init init_bootmem(unsigned long start, unsigned long pages)
 {
        max_low_pfn = pages;
        min_low_pfn = start;
        return init_bootmem_core(NODE_DATA(0)->bdata, start, 0, pages);
 }
 So, min_low_pfn is the PFN offset of the start of physical memory (so
 3GB >> PAGE_SHIFT) and max_low_pfn ends up being the number of pages,
 _not_ the maximum PFN value

So, if physical address doesn't start at 0, max_low_pfn doesn't represent 
the maximum PFN value. This is a case for ARM.

> 
> #ifdef CONFIG_X86_32
>         /* max_low_pfn get updated here */
>         find_low_pfn_range();
> #else
>         num_physpages = max_pfn;
> 
>         check_x2apic();
> 
>         /* How many end-of-memory variables you have, grandma! */
>         /* need this before calling reserve_initrd */
>         if (max_pfn > (1UL<<(32 - PAGE_SHIFT)))
>                 max_low_pfn = e820_end_of_low_ram_pfn();
>         else
>                 max_low_pfn = max_pfn;
> 
> and under max_low_pfn is bootmem.
> 
> >
> > Additionally, if 'start_pfn == end_pfn', we don't need to go futher,
> > so change range check.
> >
> > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> >
> > diff --git a/mm/nobootmem.c b/mm/nobootmem.c
> > index 5e07d36..4711e91 100644
> > --- a/mm/nobootmem.c
> > +++ b/mm/nobootmem.c
> > @@ -110,9 +110,9 @@ static unsigned long __init __free_memory_core(phys_addr_t start,
> >  {
> >         unsigned long start_pfn = PFN_UP(start);
> >         unsigned long end_pfn = min_t(unsigned long,
> > -                                     PFN_DOWN(end), max_low_pfn);
> > +                                     PFN_DOWN(end), min_low_pfn);
> 
> what is min_low_pfn ?  is it 0 for x86?

My implementation is totally wrong. :)
min_low_pfn is not proper value for this purpose.

I will fix it.
Sorry for noise.

Thanks.

> 
> Thanks
> 
> Yinghai
> 
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Re: [PATCH 1/3] mm, nobootmem: fix wrong usage of max_low_pfn

[Joonsoo Kim]

On Tue, Mar 19, 2013 at 03:25:22PM +0900, Joonsoo Kim wrote:
> On Mon, Mar 18, 2013 at 10:47:41PM -0700, Yinghai Lu wrote:
> > On Mon, Mar 18, 2013 at 10:15 PM, Joonsoo Kim <iamjoonsoo.kim@lge.com> wrote:
> > > max_low_pfn reflect the number of _pages_ in the system,
> > > not the maximum PFN. You can easily find that fact in init_bootmem().
> > > So fix it.
> > 
> > I'm confused. for x86, we have max_low_pfn defined in ...
> 
> Below is queote from Russell King in 'https://lkml.org/lkml/2013/3/13/123'
> 
> 
>  Now, max_low_pfn is initialized this way:
>  
>  /**
>   * init_bootmem - register boot memory
>   * @start: pfn where the bitmap is to be placed
>   * @pages: number of available physical pages
>   *
>   * Returns the number of bytes needed to hold the bitmap.
>   */
>  unsigned long __init init_bootmem(unsigned long start, unsigned long pages)
>  {
>         max_low_pfn = pages;
>         min_low_pfn = start;
>         return init_bootmem_core(NODE_DATA(0)->bdata, start, 0, pages);
>  }
>  So, min_low_pfn is the PFN offset of the start of physical memory (so
>  3GB >> PAGE_SHIFT) and max_low_pfn ends up being the number of pages,
>  _not_ the maximum PFN value
> 
> So, if physical address doesn't start at 0, max_low_pfn doesn't represent 
> the maximum PFN value. This is a case for ARM.
> 
> > 
> > #ifdef CONFIG_X86_32
> >         /* max_low_pfn get updated here */
> >         find_low_pfn_range();
> > #else
> >         num_physpages = max_pfn;
> > 
> >         check_x2apic();
> > 
> >         /* How many end-of-memory variables you have, grandma! */
> >         /* need this before calling reserve_initrd */
> >         if (max_pfn > (1UL<<(32 - PAGE_SHIFT)))
> >                 max_low_pfn = e820_end_of_low_ram_pfn();
> >         else
> >                 max_low_pfn = max_pfn;
> > 
> > and under max_low_pfn is bootmem.
> > 
> > >
> > > Additionally, if 'start_pfn == end_pfn', we don't need to go futher,
> > > so change range check.
> > >
> > > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> > >
> > > diff --git a/mm/nobootmem.c b/mm/nobootmem.c
> > > index 5e07d36..4711e91 100644
> > > --- a/mm/nobootmem.c
> > > +++ b/mm/nobootmem.c
> > > @@ -110,9 +110,9 @@ static unsigned long __init __free_memory_core(phys_addr_t start,
> > >  {
> > >         unsigned long start_pfn = PFN_UP(start);
> > >         unsigned long end_pfn = min_t(unsigned long,
> > > -                                     PFN_DOWN(end), max_low_pfn);
> > > +                                     PFN_DOWN(end), min_low_pfn);
> > 
> > what is min_low_pfn ?  is it 0 for x86?
> 
> My implementation is totally wrong. :)
> min_low_pfn is not proper value for this purpose.
> 
> I will fix it.
> Sorry for noise.
> 
> Thanks.

How about using "memblock.current_limit"?

unsigned long end_pfn = min_t(unsigned long, PFN_DOWN(end),
					memblock.current_limit);

Thanks.

> 
> > 
> > Thanks
> > 
> > Yinghai
> > 
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Re: [PATCH 1/3] mm, nobootmem: fix wrong usage of max_low_pfn

[Yinghai Lu]

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Can you check why sparc do not need to change interface during converting
to use memblock to replace bootmem?

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Re: [PATCH 1/3] mm, nobootmem: fix wrong usage of max_low_pfn

[Joonsoo Kim]

On Tue, Mar 19, 2013 at 12:35:45AM -0700, Yinghai Lu wrote:
> Can you check why sparc do not need to change interface during converting
> to use memblock to replace bootmem?

Sure.
According to my understanding to sparc32 code(arch/sparc/mm/init_32.c),
they already use max_low_pfn as the maximum PFN value,
not as the number of pages.

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Re: [PATCH 1/3] mm, nobootmem: fix wrong usage of max_low_pfn

[Sam Ravnborg]

On Tue, Mar 19, 2013 at 05:07:21PM +0900, Joonsoo Kim wrote:
> On Tue, Mar 19, 2013 at 12:35:45AM -0700, Yinghai Lu wrote:
> > Can you check why sparc do not need to change interface during converting
> > to use memblock to replace bootmem?
> 
> Sure.
> According to my understanding to sparc32 code(arch/sparc/mm/init_32.c),
> they already use max_low_pfn as the maximum PFN value,
> not as the number of pages.

I assume you already know...
sparc64 uses memblock, but sparc32 does not.
I looked at using memblock for sparc32 some time ago but got
distracted by other stuff.
I recall from back then that these ackward named variables confused me,
and some of my confusion was likely rooted in sparc32 using
max_low_pfn for something elase than others do.

I have no plans to look into adding memblock support for sparc32
right now. But may eventually do so when I get some spare time.

	Sam

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