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mm/page_alloc: fix freeing static percpu memory

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The size of struct per_cpu_zonestat can be 0 on !SMP && !NUMA.  In that
case, zone->per_cpu_zonestats will always equal to boot_zonestats.  But in
zone_pcp_reset(), zone->per_cpu_zonestats is freed via free_percpu()
directly without checking against boot_zonestats first.  boot_zonestats
will be released by free_percpu() unexpectedly.

Link: https://lkml.kernel.org/r/20220916072257.9639-7-linmiaohe@huawei.com
Fixes: 28f836b6777b ("mm/page_alloc: split per cpu page lists and zone stats")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Miaohe Lin 2022-09-16 15:22:47 +08:00 committed by Andrew Morton
parent 5749fcc5f0
commit 022e7fa0f7
1 changed files with 4 additions and 2 deletions
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6
mm/page_alloc.c
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@ -9513,9 +9513,11 @@ void zone_pcp_reset(struct zone *zone)
drain_zonestat(zone, pzstats);
}
free_percpu(zone->per_cpu_pageset);
free_percpu(zone->per_cpu_zonestats);
zone->per_cpu_pageset = &boot_pageset;
zone->per_cpu_zonestats = &boot_zonestats;
if (zone->per_cpu_zonestats != &boot_zonestats) {
free_percpu(zone->per_cpu_zonestats);
zone->per_cpu_zonestats = &boot_zonestats;
}
}
}