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[2003:cb:c704:6300:1fe0:42e1:62c5:91b6]) by smtp.gmail.com with ESMTPSA id h17-20020a05600c2cb100b003a5ca627333sm467212wmc.8.2022.09.09.04.28.41 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 09 Sep 2022 04:28:41 -0700 (PDT) Message-ID: <77c1ccc6-9125-ea91-45d8-7e087b38e196@redhat.com> Date: Fri, 9 Sep 2022 13:28:40 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.2.0 Subject: Re: [PATCH 06/16] mm/page_alloc: fix freeing static percpu memory Content-Language: en-US To: Miaohe Lin , akpm@linux-foundation.org Cc: osalvador@suse.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20220909092451.24883-1-linmiaohe@huawei.com> <20220909092451.24883-7-linmiaohe@huawei.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20220909092451.24883-7-linmiaohe@huawei.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09.09.22 11:24, Miaohe Lin wrote: > 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. > > Fixes: 28f836b6777b ("mm/page_alloc: split per cpu page lists and zone stats") > Signed-off-by: Miaohe Lin > --- > 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 3497919f4ef5..a35ef385d906 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -9510,9 +9510,11 @@ 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; > + } > } > } > Reviewed-by: David Hildenbrand -- Thanks, David / dhildenb