From: Vlastimil Babka <vbabka@suse.cz>
To: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org, Michal Hocko <mhocko@kernel.org>,
Pavel Tatashin <pasha.tatashin@soleen.com>,
David Hildenbrand <david@redhat.com>,
Oscar Salvador <osalvador@suse.de>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Vlastimil Babka <vbabka@suse.cz>
Subject: [PATCH 5/9] mm, page_alloc: make per_cpu_pageset accessible only after init
Date: Tue, 22 Sep 2020 16:37:08 +0200 [thread overview]
Message-ID: <20200922143712.12048-6-vbabka@suse.cz> (raw)
In-Reply-To: <20200922143712.12048-1-vbabka@suse.cz>
setup_zone_pageset() replaces the boot_pageset by allocating and initializing a
proper percpu one. Currently it assigns zone->pageset with the newly allocated
one before initializing it. That's currently not an issue, because the zone
should not be in any zonelist, thus not visible to allocators at this point.
Memory ordering between the pcplist contents and its visibility is also not
guaranteed here, but that also shouldn't be an issue because online_pages()
does a spin_unlock(pgdat->node_size_lock) before building the zonelists.
However it's best that we don't silently rely on operations that can be changed
in the future. Make sure only properly initialized pcplists are visible, using
smp_store_release(). The read side has a data dependency via the zone->pageset
pointer instead of an explicit read barrier.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
mm/page_alloc.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 99b74c1c2b0a..de3b48bda45c 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6246,15 +6246,17 @@ static void zone_set_pageset_high_and_batch(struct zone *zone)
void __meminit setup_zone_pageset(struct zone *zone)
{
+ struct per_cpu_pageset __percpu * new_pageset;
struct per_cpu_pageset *p;
int cpu;
- zone->pageset = alloc_percpu(struct per_cpu_pageset);
+ new_pageset = alloc_percpu(struct per_cpu_pageset);
for_each_possible_cpu(cpu) {
- p = per_cpu_ptr(zone->pageset, cpu);
+ p = per_cpu_ptr(new_pageset, cpu);
pageset_init(p);
}
+ smp_store_release(&zone->pageset, new_pageset);
zone_set_pageset_high_and_batch(zone);
}
--
2.28.0
next prev parent reply other threads:[~2020-09-22 14:37 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-22 14:37 [PATCH 0/9] disable pcplists during memory offline Vlastimil Babka
2020-09-22 14:37 ` [PATCH 1/9] mm, page_alloc: clean up pageset high and batch update Vlastimil Babka
2020-09-25 10:18 ` David Hildenbrand
2020-10-05 12:03 ` Michal Hocko
2020-09-22 14:37 ` [PATCH 2/9] mm, page_alloc: calculate pageset high and batch once per zone Vlastimil Babka
2020-10-05 12:52 ` Michal Hocko
2020-10-06 22:04 ` Vlastimil Babka
2020-09-22 14:37 ` [PATCH 3/9] mm, page_alloc: remove setup_pageset() Vlastimil Babka
2020-09-25 10:19 ` David Hildenbrand
2020-10-05 12:59 ` Michal Hocko
2020-10-06 22:11 ` Vlastimil Babka
2020-09-22 14:37 ` [PATCH 4/9] mm, page_alloc: simplify pageset_update() Vlastimil Babka
2020-09-25 10:23 ` David Hildenbrand
2020-10-05 13:20 ` Michal Hocko
2020-09-22 14:37 ` Vlastimil Babka [this message]
2020-09-25 10:25 ` [PATCH 5/9] mm, page_alloc: make per_cpu_pageset accessible only after init David Hildenbrand
2020-10-05 13:24 ` Michal Hocko
2020-10-06 22:28 ` Vlastimil Babka
2020-09-22 14:37 ` [PATCH 6/9] mm, page_alloc: cache pageset high and batch in struct zone Vlastimil Babka
2020-09-25 10:34 ` David Hildenbrand
2020-10-06 22:31 ` Vlastimil Babka
2020-10-05 13:28 ` Michal Hocko
2020-10-06 22:34 ` Vlastimil Babka
2020-09-22 14:37 ` [PATCH 7/9] mm, page_alloc: move draining pcplists to page isolation users Vlastimil Babka
2020-09-25 10:39 ` David Hildenbrand
2020-10-05 13:57 ` Michal Hocko
2020-09-22 14:37 ` [PATCH 8/9] mm, page_alloc: drain all pcplists during memory offline Vlastimil Babka
2020-09-25 10:46 ` David Hildenbrand
2020-10-05 14:03 ` Michal Hocko
2020-09-22 14:37 ` [PATCH 9/9] mm, page_alloc: optionally disable pcplists during page isolation Vlastimil Babka
2020-09-25 10:53 ` David Hildenbrand
2020-09-25 10:54 ` David Hildenbrand
2020-09-25 11:10 ` Vlastimil Babka
2020-10-01 8:47 ` David Hildenbrand
2020-10-05 14:05 ` Michal Hocko
2020-10-05 14:22 ` Vlastimil Babka
2020-10-05 16:56 ` Michal Hocko
2020-10-06 8:34 ` Michal Hocko
2020-10-06 8:40 ` David Hildenbrand
2020-10-06 10:05 ` Michal Hocko
2020-09-22 17:15 ` [PATCH 0/9] disable pcplists during memory offline David Hildenbrand
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