From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5FEA3C433E0 for ; Fri, 22 May 2020 23:53:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2668320738 for ; Fri, 22 May 2020 23:53:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590191584; bh=HRrdOuGUdvjl0wXxA5ZTMAtvsW5wKqP1K72cTMtDBds=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=LUsfBN3rg7ffhfpPIBarysJtmP7wSG2W4cjLEkkJZQN46v6RE4GBwJl+n95NSrVPS hHpLDQVHY8Dvz1CpQjLbdiakW9o8ip/GQFXs4g8xO6na+CoCm1id6S37g4esgF4tCW AauqPb36NoYRXAwc/CXXQei2/MlnV91fyrafwBhw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387469AbgEVXxD (ORCPT ); Fri, 22 May 2020 19:53:03 -0400 Received: from mail.kernel.org ([198.145.29.99]:58798 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387437AbgEVXxD (ORCPT ); Fri, 22 May 2020 19:53:03 -0400 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E057B206BE; Fri, 22 May 2020 23:53:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590191582; bh=HRrdOuGUdvjl0wXxA5ZTMAtvsW5wKqP1K72cTMtDBds=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=1AlseEXERTVm6vSNK1ukfK+IKevlLvrv6Ut5WPfcaxPjEQDtTwQU1c78tP25poSPW Pkl8eSf9lB28MNNLVVALtVRBzSnpqvBMMBfnOi5Q3QgSu4rEMqixny1o33eD6zyvPb ZVWFPXMqETTQHAGv+cqRhqFBFl0fIYa3FdeSmo0I= Date: Fri, 22 May 2020 16:53:01 -0700 From: Andrew Morton To: Guoqing Jiang Cc: Dave Chinner , viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, hch@infradead.org, willy@infradead.org Subject: Re: [PATCH 10/10] mm/migrate.c: call detach_page_private to cleanup code Message-Id: <20200522165301.727977de1d39ac5bfb683ed0@linux-foundation.org> In-Reply-To: <906f7469-492d-febc-c7ed-b01830ae900d@cloud.ionos.com> References: <20200517214718.468-1-guoqing.jiang@cloud.ionos.com> <20200517214718.468-11-guoqing.jiang@cloud.ionos.com> <20200521225220.GV2005@dread.disaster.area> <906f7469-492d-febc-c7ed-b01830ae900d@cloud.ionos.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 22 May 2020 09:18:25 +0200 Guoqing Jiang wrote: > >> - ClearPagePrivate(page); > >> - set_page_private(newpage, page_private(page)); > >> - set_page_private(page, 0); > >> - put_page(page); > >> + set_page_private(newpage, detach_page_private(page)); > > attach_page_private(newpage, detach_page_private(page)); > > Mattew had suggested it as follows, but not sure if we can reorder of > the setup of > the bh and setting PagePrivate, so I didn't want to break the original > syntax. > > @@ -797,11 +797,7 @@ static int __buffer_migrate_page(struct address_space *mapping, > if (rc != MIGRATEPAGE_SUCCESS) > goto unlock_buffers; > > - ClearPagePrivate(page); > - set_page_private(newpage, page_private(page)); > - set_page_private(page, 0); > - put_page(page); > - get_page(newpage); > + attach_page_private(newpage, detach_page_private(page)); > > bh = head; > do { > @@ -810,8 +806,6 @@ static int __buffer_migrate_page(struct address_space *mapping, > > } while (bh != head); > > - SetPagePrivate(newpage); > - > if (mode != MIGRATE_SYNC_NO_COPY) This is OK - coherency between PG_private and the page's buffer ring is maintained by holding lock_page(). I have (effectively) applied the above change.