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=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_NEOMUTT autolearn=ham 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 22138C5CFE7 for ; Mon, 9 Jul 2018 16:12:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C1FC520779 for ; Mon, 9 Jul 2018 16:12:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C1FC520779 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754590AbeGIQL5 (ORCPT ); Mon, 9 Jul 2018 12:11:57 -0400 Received: from mx2.suse.de ([195.135.220.15]:51788 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754556AbeGIQL4 (ORCPT ); Mon, 9 Jul 2018 12:11:56 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id A6093AC8A; Mon, 9 Jul 2018 16:11:54 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id 32E431E0DD5; Mon, 9 Jul 2018 18:11:54 +0200 (CEST) Date: Mon, 9 Jul 2018 18:11:54 +0200 From: Jan Kara To: Jason Gunthorpe Cc: john.hubbard@gmail.com, Matthew Wilcox , Michal Hocko , Christopher Lameter , Dan Williams , Jan Kara , Al Viro , linux-mm@kvack.org, LKML , linux-rdma , linux-fsdevel@vger.kernel.org, John Hubbard Subject: Re: [PATCH 1/2] mm: introduce put_user_page(), placeholder version Message-ID: <20180709161154.46chzohwnzzbrtis@quack2.suse.cz> References: <20180709080554.21931-1-jhubbard@nvidia.com> <20180709080554.21931-2-jhubbard@nvidia.com> <20180709155357.GA13496@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180709155357.GA13496@ziepe.ca> User-Agent: NeoMutt/20170912 (1.9.0) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 09-07-18 09:53:57, Jason Gunthorpe wrote: > On Mon, Jul 09, 2018 at 01:05:53AM -0700, john.hubbard@gmail.com wrote: > > From: John Hubbard > > > > Introduces put_user_page(), which simply calls put_page(). > > This provides a safe way to update all get_user_pages*() callers, > > so that they call put_user_page(), instead of put_page(). > > > > Also adds release_user_pages(), a drop-in replacement for > > release_pages(). This is intended to be easily grep-able, > > for later performance improvements, since release_user_pages > > is not batched like release_pages is, and is significantly > > slower. > > > > Subsequent patches will add functionality to put_user_page(). > > > > Signed-off-by: John Hubbard > > include/linux/mm.h | 14 ++++++++++++++ > > 1 file changed, 14 insertions(+) > > > > diff --git a/include/linux/mm.h b/include/linux/mm.h > > index a0fbb9ffe380..db4a211aad79 100644 > > +++ b/include/linux/mm.h > > @@ -923,6 +923,20 @@ static inline void put_page(struct page *page) > > __put_page(page); > > } > > > > +/* Placeholder version, until all get_user_pages*() callers are updated. */ > > +static inline void put_user_page(struct page *page) > > +{ > > + put_page(page); > > +} > > + > > +/* A drop-in replacement for release_pages(): */ > > +static inline void release_user_pages(struct page **pages, > > + unsigned long npages) > > +{ > > + while (npages) > > + put_user_page(pages[--npages]); > > +} > > + > > #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP) > > #define SECTION_IN_PAGE_FLAGS > > #endif > > Just as question: Do you think it is worthwhile to have a > release_user_page_dirtied() helper as well? > > Ie to indicate that a pages that were grabbed under GUP FOLL_WRITE > were actually written too? > > Keeps more of these unimportant details out of the drivers.. Yeah, I think that would be nice as well. Honza -- Jan Kara SUSE Labs, CR