linux-kernel - [PATCH v3 3/7] mm, page_alloc: remove setup

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 11 Nov 2020 10:28:08 +0100
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-mm@...ck.org, 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>,
        Michal Hocko <mhocko@...e.com>
Subject: [PATCH v3 3/7] 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 the proper
values.

No functional change.

Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
Reviewed-by: David Hildenbrand <david@...hat.com>
Reviewed-by: Oscar Salvador <osalvador@...e.de>
Acked-by: Michal Hocko <mhocko@...e.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