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Thu, 6 Jun 2024 09:24:38 +0800 Message-ID: <9373adb8-29be-4354-9783-f16988afbce5@huawei.com> Date: Thu, 6 Jun 2024 09:24:37 +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: Jane Chu , , , Matthew Wilcox References: <20240603092439.3360652-1-wangkefeng.wang@huawei.com> <20240603092439.3360652-4-wangkefeng.wang@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: dggems703-chm.china.huawei.com (10.3.19.180) To dggpemm100001.china.huawei.com (7.185.36.93) X-Rspamd-Queue-Id: 66687C0010 X-Stat-Signature: r15m748dteayseyxf6mdzp5bbo69uxsw X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1717637083-918728 X-HE-Meta: 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 EsO2az3r zUMHJwaux7J3romaWjXJ3OvKrz7IhEqNdeVhcGPIZFv05BppoHowrZS6djle8AOMfS4SeoOi86VXC8pB9HtyCaLYGmT8vITlZHHor3YhxyGkvJgpSEqQiiMVn4l0Spsctk8FXBjPzDMERqJNJ747kjUCVP4AeKz1mCj8lBEVjFAZ/w7wGXqEwq1Yk1YoHdpHTT4WRAgGmYsNIXjOeSwN310W0Xg== 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 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. > > The ordering change was introduced by commit > > 89eb946a7432b "(mm: Convert page migration to XArray)" > > Matthew, please correct me if I'm missing something. > > thanks, > > -jane >