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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 90163C432C1 for ; Tue, 24 Sep 2019 23:51:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 626E020640 for ; Tue, 24 Sep 2019 23:51:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="GCETbZPj" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2442120AbfIXXvU (ORCPT ); Tue, 24 Sep 2019 19:51:20 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:53224 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388576AbfIXXvU (ORCPT ); Tue, 24 Sep 2019 19:51:20 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=JhS/TGKOzXU3CFQB0XmpkctpJKKTRR5z1RS468Kk/tA=; b=GCETbZPjSdLLgOtfHcPdgmq7X M+Hf7VG4uECOVG7OAk0iIlKl0KdyoM+Vpg70Ja2WtAFj0IG7tvplbCMoTnjYJhX6Qudcux37S/Of+ agGauGSk+wbXDgkXAs/r1v2jZFRlype9ioRHm5O2dun6SpGk9C3wijqjnVCKC2ol46OPN0d5k8b5C /J6bWaXyW3EIgxs5q48q0ELjn4Q0bJPD9iYR1CLXdF/pm/QEaF/xOw2xR83cQz6KNOWInx5MGeTji Zh61xl7xuXrQbUbIx8g37qsZyNNU3DkGbaOpljGgQ9oPkJVrqiKasmJ21rNJc6EL+LU6Bf02Mc1dU ahkFrFXEA==; Received: from willy by bombadil.infradead.org with local (Exim 4.92.2 #3 (Red Hat Linux)) id 1iCuZo-00066p-ST; Tue, 24 Sep 2019 23:50:36 +0000 Date: Tue, 24 Sep 2019 16:50:36 -0700 From: Matthew Wilcox To: Yu Zhao Cc: Andrew Morton , Michal Hocko , "Kirill A . Shutemov" , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Vlastimil Babka , Hugh Dickins , =?iso-8859-1?B?Suly9G1l?= Glisse , Andrea Arcangeli , "Aneesh Kumar K . V" , David Rientjes , Lance Roy , Ralph Campbell , Jason Gunthorpe , Dave Airlie , Thomas Hellstrom , Souptick Joarder , Mel Gorman , Jan Kara , Mike Kravetz , Huang Ying , Aaron Lu , Omar Sandoval , Thomas Gleixner , Vineeth Remanan Pillai , Daniel Jordan , Mike Rapoport , Joel Fernandes , Mark Rutland , Alexander Duyck , Pavel Tatashin , David Hildenbrand , Juergen Gross , Anthony Yznaga , Johannes Weiner , "Darrick J . Wong" , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v3 4/4] mm: remove unnecessary smp_wmb() in __SetPageUptodate() Message-ID: <20190924235036.GA24516@bombadil.infradead.org> References: <20190914070518.112954-1-yuzhao@google.com> <20190924232459.214097-1-yuzhao@google.com> <20190924232459.214097-4-yuzhao@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190924232459.214097-4-yuzhao@google.com> User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 24, 2019 at 05:24:59PM -0600, Yu Zhao wrote: > +/* > + * Only use this function when there is a following write barrier, e.g., > + * an explicit smp_wmb() and/or the page will be added to page or swap > + * cache locked. > + */ > static __always_inline void __SetPageUptodate(struct page *page) > { > VM_BUG_ON_PAGE(PageTail(page), page); > - smp_wmb(); > __set_bit(PG_uptodate, &page->flags); > } Isn't this now the same as __SETPAGEFLAG(uptodate, Uptodate, PF_NO_TAIL)?