On 07/14/2017 10:00 AM, Michal Hocko wrote:
> From: Michal Hocko <mho...@suse.com>
>
> build_all_zonelists gets a zone parameter to initialize zone's
> pagesets. There is only a single user which gives a non-NULL
> zone parameter and that one doesn't really need the rest of the
> build_all_zonelists (see 6dcd73d7011b ("memory-hotplug: allocate zone's
> pcp before onlining pages")).
>
> Therefore remove setup_zone_pageset from build_all_zonelists and call it
> from its only user directly. This will also remove a pointless zonlists
> rebuilding which is always good.
>
> Cc: Wen Congyang <we...@cn.fujitsu.com>
> Signed-off-by: Michal Hocko <mho...@suse.com>
Acked-by: Vlastimil Babka <vba...@suse.cz>
with a small point below
...
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index ebc3311555b1..00e117922b3f 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5065,7 +5065,6 @@ static void build_zonelists(pg_data_t *pgdat)
> static void setup_pageset(struct per_cpu_pageset *p, unsigned long batch);
> static DEFINE_PER_CPU(struct per_cpu_pageset, boot_pageset);
> static DEFINE_PER_CPU(struct per_cpu_nodestat, boot_nodestats);
> -static void setup_zone_pageset(struct zone *zone);
>
> /*
> * Global mutex to protect against size modification of zonelists
> @@ -5146,19 +5145,14 @@ build_all_zonelists_init(void)
> * unless system_state == SYSTEM_BOOTING.
> *
> * __ref due to (1) call of __meminit annotated setup_zone_pageset
Isn't the whole (1) in the comment invalid now?
> - * [we're only called with non-NULL zone through __meminit paths] and
> - * (2) call of __init annotated helper build_all_zonelists_init
> + * and (2) call of __init annotated helper build_all_zonelists_init
> * [protected by SYSTEM_BOOTING].
> */
> -void __ref build_all_zonelists(pg_data_t *pgdat, struct zone *zone)
> +void __ref build_all_zonelists(pg_data_t *pgdat)
> {
> if (system_state == SYSTEM_BOOTING) {
> build_all_zonelists_init();
> } else {
> -#ifdef CONFIG_MEMORY_HOTPLUG
> - if (zone)
> - setup_zone_pageset(zone);
> -#endif
> /* we have to stop all cpus to guarantee there is no user
> of zonelist */
> stop_machine_cpuslocked(__build_all_zonelists, pgdat, NULL);
> @@ -5432,7 +5426,7 @@ static void __meminit zone_pageset_init(struct zone
> *zone, int cpu)
> pageset_set_high_and_batch(zone, pcp);
> }
>
> -static void __meminit setup_zone_pageset(struct zone *zone)
> +void __meminit setup_zone_pageset(struct zone *zone)
> {
> int cpu;
> zone->pageset = alloc_percpu(struct per_cpu_pageset);
>
