[PATCH 1/2] mm/page_alloc: change sysctl_lower_zone_reserve_ratio to sysctl_lowmem_reserve_ratio

[PATCH 1/2] mm/page_alloc: change sysctl_lower_zone_reserve_ratio to sysctl_lowmem_reserve_ratio

[Yaowei Bai]

We use sysctl_lowmem_reserve_ratio rather than sysctl_lower_zone_reserve_ratio to
determine how aggressive the kernel is in defending lowmem from the possibility of
being captured into pinned user memory. To avoid misleading, correct it in some
comments.

Signed-off-by: Yaowei Bai <bywxiaobai@163.com>
---
 mm/page_alloc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 0a0acdb..b730f7d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6043,7 +6043,7 @@ void __init page_alloc_init(void)
 }
 
 /*
- * calculate_totalreserve_pages - called when sysctl_lower_zone_reserve_ratio
+ * calculate_totalreserve_pages - called when sysctl_lowmem_reserve_ratio
  *	or min_free_kbytes changes.
  */
 static void calculate_totalreserve_pages(void)
@@ -6087,7 +6087,7 @@ static void calculate_totalreserve_pages(void)
 
 /*
  * setup_per_zone_lowmem_reserve - called whenever
- *	sysctl_lower_zone_reserve_ratio changes.  Ensures that each zone
+ *	sysctl_lowmem_reserve_ratio changes.  Ensures that each zone
  *	has a correct pages reserved value, so an adequate number of
  *	pages are left in the zone after a successful __alloc_pages().
  */
-- 
1.9.1


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[PATCH 2/2] Documentation: clarify in calculating zone protection

[Yaowei Bai]

Every zone's protection is calculated from managed_pages not
present_pages, to avoid misleading, correct it.

Signed-off-by: Yaowei Bai <bywxiaobai@163.com>
---
 Documentation/sysctl/vm.txt | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index 9832ec5..1739b31 100644
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -349,7 +349,7 @@ zone[i]'s protection[j] is calculated by following expression.
 
 (i < j):
   zone[i]->protection[j]
-  = (total sums of present_pages from zone[i+1] to zone[j] on the node)
+  = (total sums of managed_pages from zone[i+1] to zone[j] on the node)
     / lowmem_reserve_ratio[i];
 (i = j):
    (should not be protected. = 0;
@@ -360,7 +360,7 @@ The default values of lowmem_reserve_ratio[i] are
     256 (if zone[i] means DMA or DMA32 zone)
     32  (others).
 As above expression, they are reciprocal number of ratio.
-256 means 1/256. # of protection pages becomes about "0.39%" of total present
+256 means 1/256. # of protection pages becomes about "0.39%" of total managed
 pages of higher zones on the node.
 
 If you would like to protect more pages, smaller values are effective.
-- 
1.9.1


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Re: [PATCH 2/2] Documentation: clarify in calculating zone protection

[Michal Hocko]

On Tue 25-08-15 22:01:31, Yaowei Bai wrote:
> Every zone's protection is calculated from managed_pages not
> present_pages, to avoid misleading, correct it.

This can be folded in to your previous patch
http://marc.info/?l=linux-mm&m=144023106610358&w=2

> 
> Signed-off-by: Yaowei Bai <bywxiaobai@163.com>
> ---
>  Documentation/sysctl/vm.txt | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
> index 9832ec5..1739b31 100644
> --- a/Documentation/sysctl/vm.txt
> +++ b/Documentation/sysctl/vm.txt
> @@ -349,7 +349,7 @@ zone[i]'s protection[j] is calculated by following expression.
>  
>  (i < j):
>    zone[i]->protection[j]
> -  = (total sums of present_pages from zone[i+1] to zone[j] on the node)
> +  = (total sums of managed_pages from zone[i+1] to zone[j] on the node)
>      / lowmem_reserve_ratio[i];
>  (i = j):
>     (should not be protected. = 0;
> @@ -360,7 +360,7 @@ The default values of lowmem_reserve_ratio[i] are
>      256 (if zone[i] means DMA or DMA32 zone)
>      32  (others).
>  As above expression, they are reciprocal number of ratio.
> -256 means 1/256. # of protection pages becomes about "0.39%" of total present
> +256 means 1/256. # of protection pages becomes about "0.39%" of total managed
>  pages of higher zones on the node.
>  
>  If you would like to protect more pages, smaller values are effective.
> -- 
> 1.9.1
> 
> 
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-- 
Michal Hocko
SUSE Labs

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Re: [PATCH 1/2] mm/page_alloc: change sysctl_lower_zone_reserve_ratio to sysctl_lowmem_reserve_ratio

[Michal Hocko]

On Tue 25-08-15 22:01:30, Yaowei Bai wrote:
> We use sysctl_lowmem_reserve_ratio rather than sysctl_lower_zone_reserve_ratio to
> determine how aggressive the kernel is in defending lowmem from the possibility of
> being captured into pinned user memory. To avoid misleading, correct it in some
> comments.

We never had a sysctl like that AFAICS in git history.

> Signed-off-by: Yaowei Bai <bywxiaobai@163.com>

Acked-by: Michal Hocko <mhocko@suse.com>

> ---
>  mm/page_alloc.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 0a0acdb..b730f7d 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -6043,7 +6043,7 @@ void __init page_alloc_init(void)
>  }
>  
>  /*
> - * calculate_totalreserve_pages - called when sysctl_lower_zone_reserve_ratio
> + * calculate_totalreserve_pages - called when sysctl_lowmem_reserve_ratio
>   *	or min_free_kbytes changes.
>   */
>  static void calculate_totalreserve_pages(void)
> @@ -6087,7 +6087,7 @@ static void calculate_totalreserve_pages(void)
>  
>  /*
>   * setup_per_zone_lowmem_reserve - called whenever
> - *	sysctl_lower_zone_reserve_ratio changes.  Ensures that each zone
> + *	sysctl_lowmem_reserve_ratio changes.  Ensures that each zone
>   *	has a correct pages reserved value, so an adequate number of
>   *	pages are left in the zone after a successful __alloc_pages().
>   */
> -- 
> 1.9.1
> 
> 
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-- 
Michal Hocko
SUSE Labs

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Re: [PATCH 2/2] Documentation: clarify in calculating zone protection

[David Rientjes]

On Tue, 25 Aug 2015, Yaowei Bai wrote:

> Every zone's protection is calculated from managed_pages not
> present_pages, to avoid misleading, correct it.
> 
> Signed-off-by: Yaowei Bai <bywxiaobai@163.com>

Acked-by: David Rientjes <rientjes@google.com>

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Re: [PATCH 1/2] mm/page_alloc: change sysctl_lower_zone_reserve_ratio to sysctl_lowmem_reserve_ratio

[David Rientjes]

On Tue, 25 Aug 2015, Yaowei Bai wrote:

> We use sysctl_lowmem_reserve_ratio rather than sysctl_lower_zone_reserve_ratio to
> determine how aggressive the kernel is in defending lowmem from the possibility of
> being captured into pinned user memory. To avoid misleading, correct it in some
> comments.
> 
> Signed-off-by: Yaowei Bai <bywxiaobai@163.com>

Acked-by: David Rientjes <rientjes@google.com>

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Re: [PATCH 2/2] Documentation: clarify in calculating zone protection

[Yaowei Bai]

On Tue, Aug 25, 2015 at 05:06:33PM +0200, Michal Hocko wrote:
> On Tue 25-08-15 22:01:31, Yaowei Bai wrote:
> > Every zone's protection is calculated from managed_pages not
> > present_pages, to avoid misleading, correct it.
> 
> This can be folded in to your previous patch
> http://marc.info/?l=linux-mm&m=144023106610358&w=2

OK, thanks.

> 
> > 
> > Signed-off-by: Yaowei Bai <bywxiaobai@163.com>
> > ---
> >  Documentation/sysctl/vm.txt | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
> > index 9832ec5..1739b31 100644
> > --- a/Documentation/sysctl/vm.txt
> > +++ b/Documentation/sysctl/vm.txt
> > @@ -349,7 +349,7 @@ zone[i]'s protection[j] is calculated by following expression.
> >  
> >  (i < j):
> >    zone[i]->protection[j]
> > -  = (total sums of present_pages from zone[i+1] to zone[j] on the node)
> > +  = (total sums of managed_pages from zone[i+1] to zone[j] on the node)
> >      / lowmem_reserve_ratio[i];
> >  (i = j):
> >     (should not be protected. = 0;
> > @@ -360,7 +360,7 @@ The default values of lowmem_reserve_ratio[i] are
> >      256 (if zone[i] means DMA or DMA32 zone)
> >      32  (others).
> >  As above expression, they are reciprocal number of ratio.
> > -256 means 1/256. # of protection pages becomes about "0.39%" of total present
> > +256 means 1/256. # of protection pages becomes about "0.39%" of total managed
> >  pages of higher zones on the node.
> >  
> >  If you would like to protect more pages, smaller values are effective.
> > -- 
> > 1.9.1
> > 
> > 
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > Please read the FAQ at  http://www.tux.org/lkml/
> 
> -- 
> Michal Hocko
> SUSE Labs

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