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 71B52C433DF for ; Tue, 19 May 2020 05:12:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 417512075F for ; Tue, 19 May 2020 05:12:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589865158; bh=qrHKafA0ZTttPnEqF3hkLOvbCl6Fprw9RuG7qytReC8=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=Ly9I0IyDmBoaVeChcu4jB+dfgyB4H2LWKeVtTSMennyQ+PtWfuJ0nXCc9DFFJG9hL z7737W+DkoZyOuyrbLJ5dWJSiuTMI90FZiWT1DksQxmlvPbaznJQHnXevv7klQHAWl SVBTq1YOjTJZV/lIGAx0eKFvYwzKAGdbm7PStEgc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727044AbgESFMh (ORCPT ); Tue, 19 May 2020 01:12:37 -0400 Received: from mail.kernel.org ([198.145.29.99]:33988 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726323AbgESFMh (ORCPT ); Tue, 19 May 2020 01:12:37 -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 3B93020758; Tue, 19 May 2020 05:12:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589865156; bh=qrHKafA0ZTttPnEqF3hkLOvbCl6Fprw9RuG7qytReC8=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=nlbIrf8Fy8HDlKACQi91AHg9NqzN0RQ0bvP2OUb2TFrW0wClvkadR8udy9FhxT6j0 QUNapjpdTE6IrfWtYzBdLzBnAHKQj3h7a4JlCowDPcDkGEKeDdsS/iNy8dk528O4qg nbm9Y07gMePXo5wP9r4/4P2ShQhKEdTZ2+DDbmOc= Date: Mon, 18 May 2020 22:12:35 -0700 From: Andrew Morton To: Guoqing Jiang Cc: viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, david@fromorbit.com, hch@infradead.org, willy@infradead.org Subject: Re: [PATCH 10/10] mm/migrate.c: call detach_page_private to cleanup code Message-Id: <20200518221235.1fa32c38e5766113f78e3f0d@linux-foundation.org> In-Reply-To: <20200517214718.468-11-guoqing.jiang@cloud.ionos.com> References: <20200517214718.468-1-guoqing.jiang@cloud.ionos.com> <20200517214718.468-11-guoqing.jiang@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 Sun, 17 May 2020 23:47:18 +0200 Guoqing Jiang wrote: > We can cleanup code a little by call detach_page_private here. > > ... > > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -804,10 +804,7 @@ 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); > + set_page_private(newpage, detach_page_private(page)); > get_page(newpage); > > bh = head; mm/migrate.c: In function '__buffer_migrate_page': ./include/linux/mm_types.h:243:52: warning: assignment makes integer from pointer without a cast [-Wint-conversion] #define set_page_private(page, v) ((page)->private = (v)) ^ mm/migrate.c:800:2: note: in expansion of macro 'set_page_private' set_page_private(newpage, detach_page_private(page)); ^~~~~~~~~~~~~~~~ The fact that set_page_private(detach_page_private()) generates a type mismatch warning seems deeply wrong, surely. Please let's get the types sorted out - either unsigned long or void *, not half-one and half-the other. Whatever needs the least typecasting at callsites, I suggest. And can we please implement set_page_private() and page_private() with inlined C code? There is no need for these to be macros.