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@xxxxxxxxxxxxxxxxxxxx>
> Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxx>
> Cc: Huang Ying <ying.huang@xxxxxxxxx>
> Cc: Minchan Kim <minchan@xxxxxxxxxx>
> Cc: Wei Yang <richard.weiyang@xxxxxxxxx>
> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
> ---
> 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
