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=-1.4 required=3.0 tests=DATE_IN_PAST_06_12, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 B0776C43381 for ; Fri, 29 Mar 2019 00:58:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 86AF12183E for ; Fri, 29 Mar 2019 00:58:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728594AbfC2A6R (ORCPT ); Thu, 28 Mar 2019 20:58:17 -0400 Received: from mga14.intel.com ([192.55.52.115]:36071 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727948AbfC2A6Q (ORCPT ); Thu, 28 Mar 2019 20:58:16 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 28 Mar 2019 17:58:16 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,282,1549958400"; d="scan'208";a="135750908" Received: from iweiny-desk2.sc.intel.com ([10.3.52.157]) by fmsmga008.fm.intel.com with ESMTP; 28 Mar 2019 17:58:16 -0700 Date: Thu, 28 Mar 2019 09:57:09 -0700 From: Ira Weiny To: John Hubbard Cc: Jerome Glisse , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Dan Williams Subject: Re: [PATCH v2 02/11] mm/hmm: use reference counting for HMM struct v2 Message-ID: <20190328165708.GH31324@iweiny-DESK2.sc.intel.com> References: <20190325144011.10560-1-jglisse@redhat.com> <20190325144011.10560-3-jglisse@redhat.com> <20190328110719.GA31324@iweiny-DESK2.sc.intel.com> <20190328191122.GA5740@redhat.com> <20190328212145.GA13560@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.11.1 (2018-12-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 28, 2019 at 05:39:26PM -0700, John Hubbard wrote: > On 3/28/19 2:21 PM, Jerome Glisse wrote: > > On Thu, Mar 28, 2019 at 01:43:13PM -0700, John Hubbard wrote: > >> On 3/28/19 12:11 PM, Jerome Glisse wrote: > >>> On Thu, Mar 28, 2019 at 04:07:20AM -0700, Ira Weiny wrote: > >>>> On Mon, Mar 25, 2019 at 10:40:02AM -0400, Jerome Glisse wrote: > >>>>> From: Jérôme Glisse > [...] > >>>>> @@ -67,14 +78,9 @@ struct hmm { > >>>>> */ > >>>>> static struct hmm *hmm_register(struct mm_struct *mm) > >>>>> { > >>>>> - struct hmm *hmm = READ_ONCE(mm->hmm); > >>>>> + struct hmm *hmm = mm_get_hmm(mm); > >>>> > >>>> FWIW: having hmm_register == "hmm get" is a bit confusing... > >>> > >>> The thing is that you want only one hmm struct per process and thus > >>> if there is already one and it is not being destroy then you want to > >>> reuse it. > >>> > >>> Also this is all internal to HMM code and so it should not confuse > >>> anyone. > >>> > >> > >> Well, it has repeatedly come up, and I'd claim that it is quite > >> counter-intuitive. So if there is an easy way to make this internal > >> HMM code clearer or better named, I would really love that to happen. > >> > >> And we shouldn't ever dismiss feedback based on "this is just internal > >> xxx subsystem code, no need for it to be as clear as other parts of the > >> kernel", right? > > > > Yes but i have not seen any better alternative that present code. If > > there is please submit patch. > > > > Ira, do you have any patch you're working on, or a more detailed suggestion there? > If not, then I might (later, as it's not urgent) propose a small cleanup patch > I had in mind for the hmm_register code. But I don't want to duplicate effort > if you're already thinking about it. No I don't have anything. I was just really digging into these this time around and I was about to comment on the lack of "get's" for some "puts" when I realized that "hmm_register" _was_ the get... :-( Ira > > > thanks, > -- > John Hubbard > NVIDIA > >