linux-kernel - [RFC 3/5] mm, page_alloc(): remove setup

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Date:   Mon,  7 Sep 2020 18:36:26 +0200
From:   Vlastimil Babka <vbabka@...e.cz>
To:     linux-mm@...ck.org
Cc:     linux-kernel@...r.kernel.org, Michal Hocko <mhocko@...nel.org>,
        Pavel Tatashin <pasha.tatashin@...een.com>,
        David Hildenbrand <david@...hat.com>,
        Oscar Salvador <osalvador@...e.de>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Vlastimil Babka <vbabka@...e.cz>
Subject: [RFC 3/5] mm, page_alloc(): remove setup_pageset()

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 specific
values.

Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
---
 mm/page_alloc.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index f669a251f654..a0cab2c6055e 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5902,7 +5902,7 @@ 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();
@@ -6228,12 +6228,13 @@ 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. Proper pageset's
+	 * initialization will update them.
+	 */
+	pcp->high = 0;
+	pcp->batch  = 1;
 }
 
 static void zone_set_pageset_high_and_batch(struct zone *zone)
-- 
2.28.0