Commit 022e7fa0 authored by Miaohe Lin's avatar Miaohe Lin Committed by Andrew Morton
Browse files

mm/page_alloc: fix freeing static percpu memory 

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: 28f836b6 ("mm/page_alloc: split per cpu page lists and zone stats")
Signed-off-by: default avatarMiaohe Lin <linmiaohe@huawei.com>
Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
Reviewed-by: default avatarOscar Salvador <osalvador@suse.de>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 5749fcc5

mm/page_alloc.c

+4 −2
Original line number Diff line number Diff line
@@ -9513,11 +9513,13 @@ 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;

		if (zone->per_cpu_zonestats != &boot_zonestats) {

			free_percpu(zone->per_cpu_zonestats);

			zone->per_cpu_zonestats = &boot_zonestats;

		}

	}

}



#ifdef CONFIG_MEMORY_HOTREMOVE

/*