[PATCH v1 0/2] mm: vm_total_pages and build_all_zonelists() cleanup

[PATCH v1 0/2] mm: vm_total_pages and build_all_zonelists() cleanup

[David Hildenbrand]

Let's drop vm_total_pages and inline nr_free_pagecache_pages() into
build_all_zonelists().

David Hildenbrand (2):
  mm: drop vm_total_pages
  mm/page_alloc: drop nr_free_pagecache_pages()

 include/linux/swap.h |  2 --
 mm/memory_hotplug.c  |  3 ---
 mm/page-writeback.c  |  6 ++----
 mm/page_alloc.c      | 18 ++++--------------
 mm/vmscan.c          |  5 -----
 5 files changed, 6 insertions(+), 28 deletions(-)

-- 
2.26.2

[PATCH v1 1/2] mm: drop vm_total_pages

[David Hildenbrand]

The global variable "vm_total_pages" is a relict from older days. There
is only a single user that reads the variable - build_all_zonelists() -
and the first thing it does is updating it. Use a local variable in
build_all_zonelists() instead and drop the local variable.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 include/linux/swap.h | 1 -
 mm/memory_hotplug.c  | 3 ---
 mm/page-writeback.c  | 6 ++----
 mm/page_alloc.c      | 2 ++
 mm/vmscan.c          | 5 -----
 5 files changed, 4 insertions(+), 13 deletions(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 4c5974bb9ba94..124261acd5d0a 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -371,7 +371,6 @@ extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem,
 extern unsigned long shrink_all_memory(unsigned long nr_pages);
 extern int vm_swappiness;
 extern int remove_mapping(struct address_space *mapping, struct page *page);
-extern unsigned long vm_total_pages;
 
 extern unsigned long reclaim_pages(struct list_head *page_list);
 #ifdef CONFIG_NUMA
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 9b34e03e730a4..d682781cce48d 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -835,8 +835,6 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages,
 	kswapd_run(nid);
 	kcompactd_run(nid);
 
-	vm_total_pages = nr_free_pagecache_pages();
-
 	writeback_set_ratelimit();
 
 	memory_notify(MEM_ONLINE, &arg);
@@ -1586,7 +1584,6 @@ static int __ref __offline_pages(unsigned long start_pfn,
 		kcompactd_stop(node);
 	}
 
-	vm_total_pages = nr_free_pagecache_pages();
 	writeback_set_ratelimit();
 
 	memory_notify(MEM_OFFLINE, &arg);
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 28b3e7a675657..4e4ddd67b71e5 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2076,13 +2076,11 @@ static int page_writeback_cpu_online(unsigned int cpu)
  * Called early on to tune the page writeback dirty limits.
  *
  * We used to scale dirty pages according to how total memory
- * related to pages that could be allocated for buffers (by
- * comparing nr_free_buffer_pages() to vm_total_pages.
+ * related to pages that could be allocated for buffers.
  *
  * However, that was when we used "dirty_ratio" to scale with
  * all memory, and we don't do that any more. "dirty_ratio"
- * is now applied to total non-HIGHPAGE memory (by subtracting
- * totalhigh_pages from vm_total_pages), and as such we can't
+ * is now applied to total non-HIGHPAGE memory, and as such we can't
  * get into the old insane situation any more where we had
  * large amounts of dirty pages compared to a small amount of
  * non-HIGHMEM memory.
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 0c435b2ed665c..7b0dde69748c1 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5903,6 +5903,8 @@ build_all_zonelists_init(void)
  */
 void __ref build_all_zonelists(pg_data_t *pgdat)
 {
+	unsigned long vm_total_pages;
+
 	if (system_state == SYSTEM_BOOTING) {
 		build_all_zonelists_init();
 	} else {
diff --git a/mm/vmscan.c b/mm/vmscan.c
index b6d84326bdf2d..0010859747df2 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -170,11 +170,6 @@ struct scan_control {
  * From 0 .. 200.  Higher means more swappy.
  */
 int vm_swappiness = 60;
-/*
- * The total number of pages which are beyond the high watermark within all
- * zones.
- */
-unsigned long vm_total_pages;
 
 static void set_task_reclaim_state(struct task_struct *task,
 				   struct reclaim_state *rs)
-- 
2.26.2

[PATCH v1 2/2] mm/page_alloc: drop nr_free_pagecache_pages()

[David Hildenbrand]

nr_free_pagecache_pages() isn't used outside page_alloc.c anymore - and
the name does not really help to understand what's going on. Let's inline
it instead and add a comment.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 include/linux/swap.h |  1 -
 mm/page_alloc.c      | 16 ++--------------
 2 files changed, 2 insertions(+), 15 deletions(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 124261acd5d0a..9bde6c6b2c045 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -327,7 +327,6 @@ void workingset_update_node(struct xa_node *node);
 /* linux/mm/page_alloc.c */
 extern unsigned long totalreserve_pages;
 extern unsigned long nr_free_buffer_pages(void);
-extern unsigned long nr_free_pagecache_pages(void);
 
 /* Definition of global_zone_page_state not available yet */
 #define nr_free_pages() global_zone_page_state(NR_FREE_PAGES)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 7b0dde69748c1..c38903d1b3b4d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5177,19 +5177,6 @@ unsigned long nr_free_buffer_pages(void)
 }
 EXPORT_SYMBOL_GPL(nr_free_buffer_pages);
 
-/**
- * nr_free_pagecache_pages - count number of pages beyond high watermark
- *
- * nr_free_pagecache_pages() counts the number of pages which are beyond the
- * high watermark within all zones.
- *
- * Return: number of pages beyond high watermark within all zones.
- */
-unsigned long nr_free_pagecache_pages(void)
-{
-	return nr_free_zone_pages(gfp_zone(GFP_HIGHUSER_MOVABLE));
-}
-
 static inline void show_node(struct zone *zone)
 {
 	if (IS_ENABLED(CONFIG_NUMA))
@@ -5911,7 +5898,8 @@ void __ref build_all_zonelists(pg_data_t *pgdat)
 		__build_all_zonelists(pgdat);
 		/* cpuset refresh routine should be here */
 	}
-	vm_total_pages = nr_free_pagecache_pages();
+	/* Get the number of free pages beyond high watermark in all zones. */
+	vm_total_pages = nr_free_zone_pages(gfp_zone(GFP_HIGHUSER_MOVABLE));
 	/*
 	 * Disable grouping by mobility if the number of pages in the
 	 * system is too low to allow the mechanism to work. It would be
-- 
2.26.2

Re: [PATCH v1 1/2] mm: drop vm_total_pages

[Wei Yang]

On Fri, Jun 19, 2020 at 03:24:09PM +0200, David Hildenbrand wrote:
>The global variable "vm_total_pages" is a relict from older days. There
>is only a single user that reads the variable - build_all_zonelists() -
>and the first thing it does is updating it. Use a local variable in
>build_all_zonelists() instead and drop the local variable.
>
>Cc: Andrew Morton <akpm@linux-foundation.org>
>Cc: Johannes Weiner <hannes@cmpxchg.org>
>Cc: Michal Hocko <mhocko@suse.com>
>Cc: Huang Ying <ying.huang@intel.com>
>Cc: Minchan Kim <minchan@kernel.org>
>Cc: Wei Yang <richard.weiyang@gmail.com>
>Signed-off-by: David Hildenbrand <david@redhat.com>

Reviewed-by: Wei Yang <richard.weiyang@gmail.com>

>---
> include/linux/swap.h | 1 -
> mm/memory_hotplug.c  | 3 ---
> mm/page-writeback.c  | 6 ++----
> mm/page_alloc.c      | 2 ++
> mm/vmscan.c          | 5 -----
> 5 files changed, 4 insertions(+), 13 deletions(-)
>
>diff --git a/include/linux/swap.h b/include/linux/swap.h
>index 4c5974bb9ba94..124261acd5d0a 100644
>--- a/include/linux/swap.h
>+++ b/include/linux/swap.h
>@@ -371,7 +371,6 @@ extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem,
> extern unsigned long shrink_all_memory(unsigned long nr_pages);
> extern int vm_swappiness;
> extern int remove_mapping(struct address_space *mapping, struct page *page);
>-extern unsigned long vm_total_pages;
> 
> extern unsigned long reclaim_pages(struct list_head *page_list);
> #ifdef CONFIG_NUMA
>diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
>index 9b34e03e730a4..d682781cce48d 100644
>--- a/mm/memory_hotplug.c
>+++ b/mm/memory_hotplug.c
>@@ -835,8 +835,6 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages,
> 	kswapd_run(nid);
> 	kcompactd_run(nid);
> 
>-	vm_total_pages = nr_free_pagecache_pages();
>-
> 	writeback_set_ratelimit();
> 
> 	memory_notify(MEM_ONLINE, &arg);
>@@ -1586,7 +1584,6 @@ static int __ref __offline_pages(unsigned long start_pfn,
> 		kcompactd_stop(node);
> 	}
> 
>-	vm_total_pages = nr_free_pagecache_pages();
> 	writeback_set_ratelimit();
> 
> 	memory_notify(MEM_OFFLINE, &arg);
>diff --git a/mm/page-writeback.c b/mm/page-writeback.c
>index 28b3e7a675657..4e4ddd67b71e5 100644
>--- a/mm/page-writeback.c
>+++ b/mm/page-writeback.c
>@@ -2076,13 +2076,11 @@ static int page_writeback_cpu_online(unsigned int cpu)
>  * Called early on to tune the page writeback dirty limits.
>  *
>  * We used to scale dirty pages according to how total memory
>- * related to pages that could be allocated for buffers (by
>- * comparing nr_free_buffer_pages() to vm_total_pages.
>+ * related to pages that could be allocated for buffers.
>  *
>  * However, that was when we used "dirty_ratio" to scale with
>  * all memory, and we don't do that any more. "dirty_ratio"
>- * is now applied to total non-HIGHPAGE memory (by subtracting
>- * totalhigh_pages from vm_total_pages), and as such we can't
>+ * is now applied to total non-HIGHPAGE memory, and as such we can't
>  * get into the old insane situation any more where we had
>  * large amounts of dirty pages compared to a small amount of
>  * non-HIGHMEM memory.
>diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>index 0c435b2ed665c..7b0dde69748c1 100644
>--- a/mm/page_alloc.c
>+++ b/mm/page_alloc.c
>@@ -5903,6 +5903,8 @@ build_all_zonelists_init(void)
>  */
> void __ref build_all_zonelists(pg_data_t *pgdat)
> {
>+	unsigned long vm_total_pages;
>+
> 	if (system_state == SYSTEM_BOOTING) {
> 		build_all_zonelists_init();
> 	} else {
>diff --git a/mm/vmscan.c b/mm/vmscan.c
>index b6d84326bdf2d..0010859747df2 100644
>--- a/mm/vmscan.c
>+++ b/mm/vmscan.c
>@@ -170,11 +170,6 @@ struct scan_control {
>  * From 0 .. 200.  Higher means more swappy.
>  */
> int vm_swappiness = 60;
>-/*
>- * The total number of pages which are beyond the high watermark within all
>- * zones.
>- */
>-unsigned long vm_total_pages;
> 
> static void set_task_reclaim_state(struct task_struct *task,
> 				   struct reclaim_state *rs)
>-- 
>2.26.2

-- 
Wei Yang
Help you, Help me

Re: [PATCH v1 2/2] mm/page_alloc: drop nr_free_pagecache_pages()

[Wei Yang]

On Fri, Jun 19, 2020 at 03:24:10PM +0200, David Hildenbrand wrote:
>nr_free_pagecache_pages() isn't used outside page_alloc.c anymore - and
>the name does not really help to understand what's going on. Let's inline
>it instead and add a comment.

Not sure "inline it" is the proper word for this.

>
>Cc: Andrew Morton <akpm@linux-foundation.org>
>Cc: Johannes Weiner <hannes@cmpxchg.org>
>Cc: Michal Hocko <mhocko@suse.com>
>Cc: Minchan Kim <minchan@kernel.org>
>Cc: Huang Ying <ying.huang@intel.com>
>Cc: Wei Yang <richard.weiyang@gmail.com>
>Signed-off-by: David Hildenbrand <david@redhat.com>

Besides:

Reviewed-by: Wei Yang <richard.weiyang@gmail.com>

>---
> include/linux/swap.h |  1 -
> mm/page_alloc.c      | 16 ++--------------
> 2 files changed, 2 insertions(+), 15 deletions(-)
>
>diff --git a/include/linux/swap.h b/include/linux/swap.h
>index 124261acd5d0a..9bde6c6b2c045 100644
>--- a/include/linux/swap.h
>+++ b/include/linux/swap.h
>@@ -327,7 +327,6 @@ void workingset_update_node(struct xa_node *node);
> /* linux/mm/page_alloc.c */
> extern unsigned long totalreserve_pages;
> extern unsigned long nr_free_buffer_pages(void);
>-extern unsigned long nr_free_pagecache_pages(void);
> 
> /* Definition of global_zone_page_state not available yet */
> #define nr_free_pages() global_zone_page_state(NR_FREE_PAGES)
>diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>index 7b0dde69748c1..c38903d1b3b4d 100644
>--- a/mm/page_alloc.c
>+++ b/mm/page_alloc.c
>@@ -5177,19 +5177,6 @@ unsigned long nr_free_buffer_pages(void)
> }
> EXPORT_SYMBOL_GPL(nr_free_buffer_pages);
> 
>-/**
>- * nr_free_pagecache_pages - count number of pages beyond high watermark
>- *
>- * nr_free_pagecache_pages() counts the number of pages which are beyond the
>- * high watermark within all zones.
>- *
>- * Return: number of pages beyond high watermark within all zones.
>- */
>-unsigned long nr_free_pagecache_pages(void)
>-{
>-	return nr_free_zone_pages(gfp_zone(GFP_HIGHUSER_MOVABLE));
>-}
>-
> static inline void show_node(struct zone *zone)
> {
> 	if (IS_ENABLED(CONFIG_NUMA))
>@@ -5911,7 +5898,8 @@ void __ref build_all_zonelists(pg_data_t *pgdat)
> 		__build_all_zonelists(pgdat);
> 		/* cpuset refresh routine should be here */
> 	}
>-	vm_total_pages = nr_free_pagecache_pages();
>+	/* Get the number of free pages beyond high watermark in all zones. */
>+	vm_total_pages = nr_free_zone_pages(gfp_zone(GFP_HIGHUSER_MOVABLE));
> 	/*
> 	 * Disable grouping by mobility if the number of pages in the
> 	 * system is too low to allow the mechanism to work. It would be
>-- 
>2.26.2

-- 
Wei Yang
Help you, Help me

Re: [PATCH v1 1/2] mm: drop vm_total_pages

[Mike Rapoport]

On Fri, Jun 19, 2020 at 03:24:09PM +0200, David Hildenbrand wrote:
> The global variable "vm_total_pages" is a relict from older days. There
> is only a single user that reads the variable - build_all_zonelists() -
> and the first thing it does is updating it. Use a local variable in
> build_all_zonelists() instead and drop the local variable.

Nit:                                       ^ global

> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Huang Ying <ying.huang@intel.com>
> Cc: Minchan Kim <minchan@kernel.org>
> Cc: Wei Yang <richard.weiyang@gmail.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>

Except the nit above

Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>

> ---
>  include/linux/swap.h | 1 -
>  mm/memory_hotplug.c  | 3 ---
>  mm/page-writeback.c  | 6 ++----
>  mm/page_alloc.c      | 2 ++
>  mm/vmscan.c          | 5 -----
>  5 files changed, 4 insertions(+), 13 deletions(-)
> 
> diff --git a/include/linux/swap.h b/include/linux/swap.h
> index 4c5974bb9ba94..124261acd5d0a 100644
> --- a/include/linux/swap.h
> +++ b/include/linux/swap.h
> @@ -371,7 +371,6 @@ extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem,
>  extern unsigned long shrink_all_memory(unsigned long nr_pages);
>  extern int vm_swappiness;
>  extern int remove_mapping(struct address_space *mapping, struct page *page);
> -extern unsigned long vm_total_pages;
>  
>  extern unsigned long reclaim_pages(struct list_head *page_list);
>  #ifdef CONFIG_NUMA
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 9b34e03e730a4..d682781cce48d 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -835,8 +835,6 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages,
>  	kswapd_run(nid);
>  	kcompactd_run(nid);
>  
> -	vm_total_pages = nr_free_pagecache_pages();
> -
>  	writeback_set_ratelimit();
>  
>  	memory_notify(MEM_ONLINE, &arg);
> @@ -1586,7 +1584,6 @@ static int __ref __offline_pages(unsigned long start_pfn,
>  		kcompactd_stop(node);
>  	}
>  
> -	vm_total_pages = nr_free_pagecache_pages();
>  	writeback_set_ratelimit();
>  
>  	memory_notify(MEM_OFFLINE, &arg);
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index 28b3e7a675657..4e4ddd67b71e5 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -2076,13 +2076,11 @@ static int page_writeback_cpu_online(unsigned int cpu)
>   * Called early on to tune the page writeback dirty limits.
>   *
>   * We used to scale dirty pages according to how total memory
> - * related to pages that could be allocated for buffers (by
> - * comparing nr_free_buffer_pages() to vm_total_pages.
> + * related to pages that could be allocated for buffers.
>   *
>   * However, that was when we used "dirty_ratio" to scale with
>   * all memory, and we don't do that any more. "dirty_ratio"
> - * is now applied to total non-HIGHPAGE memory (by subtracting
> - * totalhigh_pages from vm_total_pages), and as such we can't
> + * is now applied to total non-HIGHPAGE memory, and as such we can't
>   * get into the old insane situation any more where we had
>   * large amounts of dirty pages compared to a small amount of
>   * non-HIGHMEM memory.
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 0c435b2ed665c..7b0dde69748c1 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5903,6 +5903,8 @@ build_all_zonelists_init(void)
>   */
>  void __ref build_all_zonelists(pg_data_t *pgdat)
>  {
> +	unsigned long vm_total_pages;
> +
>  	if (system_state == SYSTEM_BOOTING) {
>  		build_all_zonelists_init();
>  	} else {
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index b6d84326bdf2d..0010859747df2 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -170,11 +170,6 @@ struct scan_control {
>   * From 0 .. 200.  Higher means more swappy.
>   */
>  int vm_swappiness = 60;
> -/*
> - * The total number of pages which are beyond the high watermark within all
> - * zones.
> - */
> -unsigned long vm_total_pages;
>  
>  static void set_task_reclaim_state(struct task_struct *task,
>  				   struct reclaim_state *rs)
> -- 
> 2.26.2
> 
> 

-- 
Sincerely yours,
Mike.

Re: [PATCH v1 2/2] mm/page_alloc: drop nr_free_pagecache_pages()

[Mike Rapoport]

On Fri, Jun 19, 2020 at 03:24:10PM +0200, David Hildenbrand wrote:
> nr_free_pagecache_pages() isn't used outside page_alloc.c anymore - and
> the name does not really help to understand what's going on. Let's inline
> it instead and add a comment.
> 
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Minchan Kim <minchan@kernel.org>
> Cc: Huang Ying <ying.huang@intel.com>
> Cc: Wei Yang <richard.weiyang@gmail.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>

Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>

> ---
>  include/linux/swap.h |  1 -
>  mm/page_alloc.c      | 16 ++--------------
>  2 files changed, 2 insertions(+), 15 deletions(-)
> 
> diff --git a/include/linux/swap.h b/include/linux/swap.h
> index 124261acd5d0a..9bde6c6b2c045 100644
> --- a/include/linux/swap.h
> +++ b/include/linux/swap.h
> @@ -327,7 +327,6 @@ void workingset_update_node(struct xa_node *node);
>  /* linux/mm/page_alloc.c */
>  extern unsigned long totalreserve_pages;
>  extern unsigned long nr_free_buffer_pages(void);
> -extern unsigned long nr_free_pagecache_pages(void);
>  
>  /* Definition of global_zone_page_state not available yet */
>  #define nr_free_pages() global_zone_page_state(NR_FREE_PAGES)
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 7b0dde69748c1..c38903d1b3b4d 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5177,19 +5177,6 @@ unsigned long nr_free_buffer_pages(void)
>  }
>  EXPORT_SYMBOL_GPL(nr_free_buffer_pages);
>  
> -/**
> - * nr_free_pagecache_pages - count number of pages beyond high watermark
> - *
> - * nr_free_pagecache_pages() counts the number of pages which are beyond the
> - * high watermark within all zones.
> - *
> - * Return: number of pages beyond high watermark within all zones.
> - */
> -unsigned long nr_free_pagecache_pages(void)
> -{
> -	return nr_free_zone_pages(gfp_zone(GFP_HIGHUSER_MOVABLE));
> -}
> -
>  static inline void show_node(struct zone *zone)
>  {
>  	if (IS_ENABLED(CONFIG_NUMA))
> @@ -5911,7 +5898,8 @@ void __ref build_all_zonelists(pg_data_t *pgdat)
>  		__build_all_zonelists(pgdat);
>  		/* cpuset refresh routine should be here */
>  	}
> -	vm_total_pages = nr_free_pagecache_pages();
> +	/* Get the number of free pages beyond high watermark in all zones. */
> +	vm_total_pages = nr_free_zone_pages(gfp_zone(GFP_HIGHUSER_MOVABLE));
>  	/*
>  	 * Disable grouping by mobility if the number of pages in the
>  	 * system is too low to allow the mechanism to work. It would be
> -- 
> 2.26.2
> 
> 

-- 
Sincerely yours,
Mike.

Re: [PATCH v1 1/2] mm: drop vm_total_pages

[Pankaj Gupta]

> The global variable "vm_total_pages" is a relict from older days. There
> is only a single user that reads the variable - build_all_zonelists() -
> and the first thing it does is updating it. Use a local variable in
> build_all_zonelists() instead and drop the local variable.
>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Huang Ying <ying.huang@intel.com>
> Cc: Minchan Kim <minchan@kernel.org>
> Cc: Wei Yang <richard.weiyang@gmail.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>  include/linux/swap.h | 1 -
>  mm/memory_hotplug.c  | 3 ---
>  mm/page-writeback.c  | 6 ++----
>  mm/page_alloc.c      | 2 ++
>  mm/vmscan.c          | 5 -----
>  5 files changed, 4 insertions(+), 13 deletions(-)
>
> diff --git a/include/linux/swap.h b/include/linux/swap.h
> index 4c5974bb9ba94..124261acd5d0a 100644
> --- a/include/linux/swap.h
> +++ b/include/linux/swap.h
> @@ -371,7 +371,6 @@ extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem,
>  extern unsigned long shrink_all_memory(unsigned long nr_pages);
>  extern int vm_swappiness;
>  extern int remove_mapping(struct address_space *mapping, struct page *page);
> -extern unsigned long vm_total_pages;
>
>  extern unsigned long reclaim_pages(struct list_head *page_list);
>  #ifdef CONFIG_NUMA
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 9b34e03e730a4..d682781cce48d 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -835,8 +835,6 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages,
>         kswapd_run(nid);
>         kcompactd_run(nid);
>
> -       vm_total_pages = nr_free_pagecache_pages();
> -
>         writeback_set_ratelimit();
>
>         memory_notify(MEM_ONLINE, &arg);
> @@ -1586,7 +1584,6 @@ static int __ref __offline_pages(unsigned long start_pfn,
>                 kcompactd_stop(node);
>         }
>
> -       vm_total_pages = nr_free_pagecache_pages();
>         writeback_set_ratelimit();
>
>         memory_notify(MEM_OFFLINE, &arg);
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index 28b3e7a675657..4e4ddd67b71e5 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -2076,13 +2076,11 @@ static int page_writeback_cpu_online(unsigned int cpu)
>   * Called early on to tune the page writeback dirty limits.
>   *
>   * We used to scale dirty pages according to how total memory
> - * related to pages that could be allocated for buffers (by
> - * comparing nr_free_buffer_pages() to vm_total_pages.
> + * related to pages that could be allocated for buffers.
>   *
>   * However, that was when we used "dirty_ratio" to scale with
>   * all memory, and we don't do that any more. "dirty_ratio"
> - * is now applied to total non-HIGHPAGE memory (by subtracting
> - * totalhigh_pages from vm_total_pages), and as such we can't
> + * is now applied to total non-HIGHPAGE memory, and as such we can't
>   * get into the old insane situation any more where we had
>   * large amounts of dirty pages compared to a small amount of
>   * non-HIGHMEM memory.
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 0c435b2ed665c..7b0dde69748c1 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5903,6 +5903,8 @@ build_all_zonelists_init(void)
>   */
>  void __ref build_all_zonelists(pg_data_t *pgdat)
>  {
> +       unsigned long vm_total_pages;
> +
>         if (system_state == SYSTEM_BOOTING) {
>                 build_all_zonelists_init();
>         } else {
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index b6d84326bdf2d..0010859747df2 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -170,11 +170,6 @@ struct scan_control {
>   * From 0 .. 200.  Higher means more swappy.
>   */
>  int vm_swappiness = 60;
> -/*
> - * The total number of pages which are beyond the high watermark within all
> - * zones.
> - */
> -unsigned long vm_total_pages;
>
>  static void set_task_reclaim_state(struct task_struct *task,
>                                    struct reclaim_state *rs)

Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>

Re: [PATCH v1 2/2] mm/page_alloc: drop nr_free_pagecache_pages()

[Pankaj Gupta]

> nr_free_pagecache_pages() isn't used outside page_alloc.c anymore - and
> the name does not really help to understand what's going on. Let's inline
> it instead and add a comment.
>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Minchan Kim <minchan@kernel.org>
> Cc: Huang Ying <ying.huang@intel.com>
> Cc: Wei Yang <richard.weiyang@gmail.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>  include/linux/swap.h |  1 -
>  mm/page_alloc.c      | 16 ++--------------
>  2 files changed, 2 insertions(+), 15 deletions(-)
>
> diff --git a/include/linux/swap.h b/include/linux/swap.h
> index 124261acd5d0a..9bde6c6b2c045 100644
> --- a/include/linux/swap.h
> +++ b/include/linux/swap.h
> @@ -327,7 +327,6 @@ void workingset_update_node(struct xa_node *node);
>  /* linux/mm/page_alloc.c */
>  extern unsigned long totalreserve_pages;
>  extern unsigned long nr_free_buffer_pages(void);
> -extern unsigned long nr_free_pagecache_pages(void);
>
>  /* Definition of global_zone_page_state not available yet */
>  #define nr_free_pages() global_zone_page_state(NR_FREE_PAGES)
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 7b0dde69748c1..c38903d1b3b4d 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5177,19 +5177,6 @@ unsigned long nr_free_buffer_pages(void)
>  }
>  EXPORT_SYMBOL_GPL(nr_free_buffer_pages);
>
> -/**
> - * nr_free_pagecache_pages - count number of pages beyond high watermark
> - *
> - * nr_free_pagecache_pages() counts the number of pages which are beyond the
> - * high watermark within all zones.
> - *
> - * Return: number of pages beyond high watermark within all zones.
> - */
> -unsigned long nr_free_pagecache_pages(void)
> -{
> -       return nr_free_zone_pages(gfp_zone(GFP_HIGHUSER_MOVABLE));
> -}
> -
>  static inline void show_node(struct zone *zone)
>  {
>         if (IS_ENABLED(CONFIG_NUMA))
> @@ -5911,7 +5898,8 @@ void __ref build_all_zonelists(pg_data_t *pgdat)
>                 __build_all_zonelists(pgdat);
>                 /* cpuset refresh routine should be here */
>         }
> -       vm_total_pages = nr_free_pagecache_pages();
> +       /* Get the number of free pages beyond high watermark in all zones. */
> +       vm_total_pages = nr_free_zone_pages(gfp_zone(GFP_HIGHUSER_MOVABLE));
>         /*
>          * Disable grouping by mobility if the number of pages in the
>          * system is too low to allow the mechanism to work. It would be

Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>

Re: [PATCH v1 1/2] mm: drop vm_total_pages

[David Hildenbrand]

On 21.06.20 16:46, Mike Rapoport wrote:
> On Fri, Jun 19, 2020 at 03:24:09PM +0200, David Hildenbrand wrote:
>> The global variable "vm_total_pages" is a relict from older days. There
>> is only a single user that reads the variable - build_all_zonelists() -
>> and the first thing it does is updating it. Use a local variable in
>> build_all_zonelists() instead and drop the local variable.
> 
> Nit:                                       ^ global

Indeed, @Andrew, can you fix this up?

Thanks!


-- 
Thanks,

David / dhildenb

Re: [PATCH v1 1/2] mm: drop vm_total_pages

[Michal Hocko]

On Fri 19-06-20 15:24:09, David Hildenbrand wrote:
> The global variable "vm_total_pages" is a relict from older days. There
> is only a single user that reads the variable - build_all_zonelists() -
> and the first thing it does is updating it. Use a local variable in
> build_all_zonelists() instead and drop the local variable.
> 
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Huang Ying <ying.huang@intel.com>
> Cc: Minchan Kim <minchan@kernel.org>
> Cc: Wei Yang <richard.weiyang@gmail.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>

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

> ---
>  include/linux/swap.h | 1 -
>  mm/memory_hotplug.c  | 3 ---
>  mm/page-writeback.c  | 6 ++----
>  mm/page_alloc.c      | 2 ++
>  mm/vmscan.c          | 5 -----
>  5 files changed, 4 insertions(+), 13 deletions(-)
> 
> diff --git a/include/linux/swap.h b/include/linux/swap.h
> index 4c5974bb9ba94..124261acd5d0a 100644
> --- a/include/linux/swap.h
> +++ b/include/linux/swap.h
> @@ -371,7 +371,6 @@ extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem,
>  extern unsigned long shrink_all_memory(unsigned long nr_pages);
>  extern int vm_swappiness;
>  extern int remove_mapping(struct address_space *mapping, struct page *page);
> -extern unsigned long vm_total_pages;
>  
>  extern unsigned long reclaim_pages(struct list_head *page_list);
>  #ifdef CONFIG_NUMA
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 9b34e03e730a4..d682781cce48d 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -835,8 +835,6 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages,
>  	kswapd_run(nid);
>  	kcompactd_run(nid);
>  
> -	vm_total_pages = nr_free_pagecache_pages();
> -
>  	writeback_set_ratelimit();
>  
>  	memory_notify(MEM_ONLINE, &arg);
> @@ -1586,7 +1584,6 @@ static int __ref __offline_pages(unsigned long start_pfn,
>  		kcompactd_stop(node);
>  	}
>  
> -	vm_total_pages = nr_free_pagecache_pages();
>  	writeback_set_ratelimit();
>  
>  	memory_notify(MEM_OFFLINE, &arg);
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index 28b3e7a675657..4e4ddd67b71e5 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -2076,13 +2076,11 @@ static int page_writeback_cpu_online(unsigned int cpu)
>   * Called early on to tune the page writeback dirty limits.
>   *
>   * We used to scale dirty pages according to how total memory
> - * related to pages that could be allocated for buffers (by
> - * comparing nr_free_buffer_pages() to vm_total_pages.
> + * related to pages that could be allocated for buffers.
>   *
>   * However, that was when we used "dirty_ratio" to scale with
>   * all memory, and we don't do that any more. "dirty_ratio"
> - * is now applied to total non-HIGHPAGE memory (by subtracting
> - * totalhigh_pages from vm_total_pages), and as such we can't
> + * is now applied to total non-HIGHPAGE memory, and as such we can't
>   * get into the old insane situation any more where we had
>   * large amounts of dirty pages compared to a small amount of
>   * non-HIGHMEM memory.
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 0c435b2ed665c..7b0dde69748c1 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5903,6 +5903,8 @@ build_all_zonelists_init(void)
>   */
>  void __ref build_all_zonelists(pg_data_t *pgdat)
>  {
> +	unsigned long vm_total_pages;
> +
>  	if (system_state == SYSTEM_BOOTING) {
>  		build_all_zonelists_init();
>  	} else {
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index b6d84326bdf2d..0010859747df2 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -170,11 +170,6 @@ struct scan_control {
>   * From 0 .. 200.  Higher means more swappy.
>   */
>  int vm_swappiness = 60;
> -/*
> - * The total number of pages which are beyond the high watermark within all
> - * zones.
> - */
> -unsigned long vm_total_pages;
>  
>  static void set_task_reclaim_state(struct task_struct *task,
>  				   struct reclaim_state *rs)
> -- 
> 2.26.2

-- 
Michal Hocko
SUSE Labs

Re: [PATCH v1 2/2] mm/page_alloc: drop nr_free_pagecache_pages()

[Michal Hocko]

On Fri 19-06-20 15:24:10, David Hildenbrand wrote:
> nr_free_pagecache_pages() isn't used outside page_alloc.c anymore - and
> the name does not really help to understand what's going on. Let's inline
> it instead and add a comment.
> 
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Minchan Kim <minchan@kernel.org>
> Cc: Huang Ying <ying.huang@intel.com>
> Cc: Wei Yang <richard.weiyang@gmail.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>

nr_free_pagecache_pages was an awkward name which kind of makes sense
but it is terribly confusing (e.g. there are pagecache consumers
restricted to lowmem zones only).

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

> ---
>  include/linux/swap.h |  1 -
>  mm/page_alloc.c      | 16 ++--------------
>  2 files changed, 2 insertions(+), 15 deletions(-)
> 
> diff --git a/include/linux/swap.h b/include/linux/swap.h
> index 124261acd5d0a..9bde6c6b2c045 100644
> --- a/include/linux/swap.h
> +++ b/include/linux/swap.h
> @@ -327,7 +327,6 @@ void workingset_update_node(struct xa_node *node);
>  /* linux/mm/page_alloc.c */
>  extern unsigned long totalreserve_pages;
>  extern unsigned long nr_free_buffer_pages(void);
> -extern unsigned long nr_free_pagecache_pages(void);
>  
>  /* Definition of global_zone_page_state not available yet */
>  #define nr_free_pages() global_zone_page_state(NR_FREE_PAGES)
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 7b0dde69748c1..c38903d1b3b4d 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5177,19 +5177,6 @@ unsigned long nr_free_buffer_pages(void)
>  }
>  EXPORT_SYMBOL_GPL(nr_free_buffer_pages);
>  
> -/**
> - * nr_free_pagecache_pages - count number of pages beyond high watermark
> - *
> - * nr_free_pagecache_pages() counts the number of pages which are beyond the
> - * high watermark within all zones.
> - *
> - * Return: number of pages beyond high watermark within all zones.
> - */
> -unsigned long nr_free_pagecache_pages(void)
> -{
> -	return nr_free_zone_pages(gfp_zone(GFP_HIGHUSER_MOVABLE));
> -}
> -
>  static inline void show_node(struct zone *zone)
>  {
>  	if (IS_ENABLED(CONFIG_NUMA))
> @@ -5911,7 +5898,8 @@ void __ref build_all_zonelists(pg_data_t *pgdat)
>  		__build_all_zonelists(pgdat);
>  		/* cpuset refresh routine should be here */
>  	}
> -	vm_total_pages = nr_free_pagecache_pages();
> +	/* Get the number of free pages beyond high watermark in all zones. */
> +	vm_total_pages = nr_free_zone_pages(gfp_zone(GFP_HIGHUSER_MOVABLE));
>  	/*
>  	 * Disable grouping by mobility if the number of pages in the
>  	 * system is too low to allow the mechanism to work. It would be
> -- 
> 2.26.2

-- 
Michal Hocko
SUSE Labs