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Thu, 6 Jun 2024 10:24:26 +0800 Message-ID: <8bee214b-d660-4b07-9761-5bf89058f9d7@huawei.com> Date: Thu, 6 Jun 2024 10:24:26 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 3/6] mm: migrate: split folio_migrate_mapping() Content-Language: en-US To: Matthew Wilcox CC: Jane Chu , , References: <20240603092439.3360652-1-wangkefeng.wang@huawei.com> <20240603092439.3360652-4-wangkefeng.wang@huawei.com> <9373adb8-29be-4354-9783-f16988afbce5@huawei.com> From: Kefeng Wang In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To dggpemm100001.china.huawei.com (7.185.36.93) X-Stat-Signature: myxg98de3k3sm157br7qkh9aqx5ew99y X-Rspamd-Queue-Id: 77FE610000A X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1717640673-265571 X-HE-Meta: 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 CeGHZWgX aeRhFTS/P5qcIxAQzsZsr9c5lGTnjKe8yH3lOmcfHqDbNfrnMqYqwIzuFCGY02hlCJZViG60lqLw8GcZro0MAntKU5VgujDluAsk7zOIYvLC/26zoAQXN9/irXBJcg0iRkn6mGhxSRlYcQbEFtesag/ivtQICFF2w9ErbMRJMmQzMK5HyR4VXl5DkLD8XxSoaOm68Jwb3aa9lVVw9wKmV6a1YZw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2024/6/6 9:55, Matthew Wilcox wrote: > On Thu, Jun 06, 2024 at 09:24:37AM +0800, Kefeng Wang wrote: >> On 2024/6/6 8:54, Jane Chu wrote: >>> [..] >>>> -int folio_migrate_mapping(struct address_space *mapping, >>>> - struct folio *newfolio, struct folio *folio, int extra_count) >>>> +static void __folio_migrate_mapping(struct address_space *mapping, >>>> + struct folio *newfolio, struct folio *folio, int expected_cnt) >>>> { >>>> XA_STATE(xas, &mapping->i_pages, folio_index(folio)); >>>> struct zone *oldzone, *newzone; >>>> - int dirty; >>>> - int expected_count = folio_expected_refs(mapping, folio) + extra_count; >>>> long nr = folio_nr_pages(folio); >>>> long entries, i; >>>> + int dirty; >>>> if (!mapping) { >>>> - /* Anonymous page without mapping */ >>> >>> If 'mapping' was NULL, the first line would blow up while dereferencing >>> 'mapping->i_pages'. >> >> 0->i_pages is wrong, but &(0->i_pages) is legal, and then xas->xa = NULL. > > Uhh, it's not NULL, but it will be a small integer (offsetof(struct > address_space, i_pages)). Oh, indeed, forget the offset, thanks. >