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    Subject[PATCH v3 3/7] mm, page_alloc: remove setup_pageset()
    Date
    We initialize boot-time pagesets with setup_pageset(), which sets high and
    batch values that effectively disable pcplists.

    We can remove this wrapper if we just set these values for all pagesets in
    pageset_init(). Non-boot pagesets then subsequently update them to the proper
    values.

    No functional change.

    Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
    Reviewed-by: David Hildenbrand <david@redhat.com>
    Reviewed-by: Oscar Salvador <osalvador@suse.de>
    Acked-by: Michal Hocko <mhocko@suse.com>
    ---
    mm/page_alloc.c | 17 ++++++++++-------
    1 file changed, 10 insertions(+), 7 deletions(-)

    diff --git a/mm/page_alloc.c b/mm/page_alloc.c
    index 2fa432762908..5a8ec7d94884 100644
    --- a/mm/page_alloc.c
    +++ b/mm/page_alloc.c
    @@ -5911,7 +5911,7 @@ static void build_zonelists(pg_data_t *pgdat)
    * not check if the processor is online before following the pageset pointer.
    * Other parts of the kernel may not check if the zone is available.
    */
    -static void setup_pageset(struct per_cpu_pageset *p);
    +static void pageset_init(struct per_cpu_pageset *p);
    static DEFINE_PER_CPU(struct per_cpu_pageset, boot_pageset);
    static DEFINE_PER_CPU(struct per_cpu_nodestat, boot_nodestats);

    @@ -5979,7 +5979,7 @@ build_all_zonelists_init(void)
    * (a chicken-egg dilemma).
    */
    for_each_possible_cpu(cpu)
    - setup_pageset(&per_cpu(boot_pageset, cpu));
    + pageset_init(&per_cpu(boot_pageset, cpu));

    mminit_verify_zonelist();
    cpuset_init_current_mems_allowed();
    @@ -6298,12 +6298,15 @@ static void pageset_init(struct per_cpu_pageset *p)
    pcp = &p->pcp;
    for (migratetype = 0; migratetype < MIGRATE_PCPTYPES; migratetype++)
    INIT_LIST_HEAD(&pcp->lists[migratetype]);
    -}

    -static void setup_pageset(struct per_cpu_pageset *p)
    -{
    - pageset_init(p);
    - pageset_update(&p->pcp, 0, 1);
    + /*
    + * Set batch and high values safe for a boot pageset. A true percpu
    + * pageset's initialization will update them subsequently. Here we don't
    + * need to be as careful as pageset_update() as nobody can access the
    + * pageset yet.
    + */
    + pcp->high = 0;
    + pcp->batch = 1;
    }

    /*
    --
    2.29.1
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