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[209.132.183.28]) by mx.google.com with ESMTPS id z40si435780qtz.287.2019.03.28.18.43.03 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 28 Mar 2019 18:43:03 -0700 (PDT) Received-SPF: pass (google.com: domain of jglisse@redhat.com designates 209.132.183.28 as permitted sender) client-ip=209.132.183.28; Authentication-Results: mx.google.com; spf=pass (google.com: domain of jglisse@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=jglisse@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 735573082E1E; Fri, 29 Mar 2019 01:43:02 +0000 (UTC) Received: from redhat.com (ovpn-121-118.rdu2.redhat.com [10.10.121.118]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 787981001E6E; Fri, 29 Mar 2019 01:43:01 +0000 (UTC) Date: Thu, 28 Mar 2019 21:42:59 -0400 From: Jerome Glisse To: John Hubbard Cc: Ira Weiny , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Dan Williams Subject: Re: [PATCH v2 07/11] mm/hmm: add default fault flags to avoid the need to pre-fill pfns arrays. Message-ID: <20190329014259.GD16680@redhat.com> References: <2f790427-ea87-b41e-b386-820ccdb7dd38@nvidia.com> <20190328221203.GF13560@redhat.com> <555ad864-d1f9-f513-9666-0d3d05dbb85d@nvidia.com> <20190328223153.GG13560@redhat.com> <768f56f5-8019-06df-2c5a-b4187deaac59@nvidia.com> <20190328232125.GJ13560@redhat.com> <20190328164231.GF31324@iweiny-DESK2.sc.intel.com> <20190329011727.GC16680@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/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Fri, 29 Mar 2019 01:43:02 +0000 (UTC) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Mar 28, 2019 at 06:30:26PM -0700, John Hubbard wrote: > On 3/28/19 6:17 PM, Jerome Glisse wrote: > > On Thu, Mar 28, 2019 at 09:42:31AM -0700, Ira Weiny wrote: > >> On Thu, Mar 28, 2019 at 04:28:47PM -0700, John Hubbard wrote: > >>> On 3/28/19 4:21 PM, Jerome Glisse wrote: > >>>> On Thu, Mar 28, 2019 at 03:40:42PM -0700, John Hubbard wrote: > >>>>> On 3/28/19 3:31 PM, Jerome Glisse wrote: > >>>>>> On Thu, Mar 28, 2019 at 03:19:06PM -0700, John Hubbard wrote: > >>>>>>> On 3/28/19 3:12 PM, Jerome Glisse wrote: > >>>>>>>> On Thu, Mar 28, 2019 at 02:59:50PM -0700, John Hubbard wrote: > >>>>>>>>> On 3/25/19 7:40 AM, jglisse@redhat.com wrote: > >>>>>>>>>> From: Jérôme Glisse > >>> [...] > >> Indeed I did not realize there is an hmm "pfn" until I saw this function: > >> > >> /* > >> * hmm_pfn_from_pfn() - create a valid HMM pfn value from pfn > >> * @range: range use to encode HMM pfn value > >> * @pfn: pfn value for which to create the HMM pfn > >> * Returns: valid HMM pfn for the pfn > >> */ > >> static inline uint64_t hmm_pfn_from_pfn(const struct hmm_range *range, > >> unsigned long pfn) > >> > >> So should this patch contain some sort of helper like this... maybe? > >> > >> I'm assuming the "hmm_pfn" being returned above is the device pfn being > >> discussed here? > >> > >> I'm also thinking calling it pfn is confusing. I'm not advocating a new type > >> but calling the "device pfn's" "hmm_pfn" or "device_pfn" seems like it would > >> have shortened the discussion here. > >> > > > > That helper is also use today by nouveau so changing that name is not that > > easy it does require the multi-release dance. So i am not sure how much > > value there is in a name change. > > > > Once the dust settles, I would expect that a name change for this could go > via Andrew's tree, right? It seems incredible to claim that we've built something > that effectively does not allow any minor changes! > > I do think it's worth some *minor* trouble to improve the name, assuming that we > can do it in a simple patch, rather than some huge maintainer-level effort. Change to nouveau have to go through nouveau tree so changing name means: - release N add function with new name, maybe make the old function just a wrapper to the new function - release N+1 update user to use the new name - release N+2 remove the old name So it is do-able but it is painful so i rather do that one latter that now as i am sure people will then complain again about some little thing and it will post pone this whole patchset on that new bit. To avoid post-poning RDMA and bunch of other patchset that build on top of that i rather get this patchset in and then do more changes in the next cycle. This is just a capacity thing. Cheers, Jérôme