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Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1sF2LY-0000000EgCY-2vCl; Thu, 06 Jun 2024 01:55:20 +0000 Date: Thu, 6 Jun 2024 02:55:20 +0100 From: Matthew Wilcox To: Kefeng Wang Cc: Jane Chu , akpm@linux-foundation.org, linux-mm@kvack.org Subject: Re: [PATCH v4 3/6] mm: migrate: split folio_migrate_mapping() Message-ID: References: <20240603092439.3360652-1-wangkefeng.wang@huawei.com> <20240603092439.3360652-4-wangkefeng.wang@huawei.com> <9373adb8-29be-4354-9783-f16988afbce5@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9373adb8-29be-4354-9783-f16988afbce5@huawei.com> X-Rspam-User: X-Stat-Signature: jcko1xwztc8ws5fc68pmgfeaho8f5mte X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 79A21140004 X-HE-Tag: 1717638928-738759 X-HE-Meta: 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 qRYLBbsj CmSeOpJreixL0pV4AM4nUPe3C6eFVGxF0yxw0+hXfp8aUchRq8gv1mJw7ulR9k1UgjjojiFM+afsxt4SJTzM35qvVFgWk7NeDUTtTZwQ0NxUfEHTP0m2a5j3r+45FulnGqJlDTgd+8JvwLwSVsX2qIGlEKpkMcENUNfa++ydaz1CN/PKNbAoXs3XhGw== 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 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)).