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[209.85.220.65]) by mx.google.com with SMTPS id i7sor9536872oto.26.2019.06.19.12.46.13 for (Google Transport Security); Wed, 19 Jun 2019 12:46:13 -0700 (PDT) Received-SPF: pass (google.com: domain of dan.j.williams@intel.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@intel-com.20150623.gappssmtp.com header.s=20150623 header.b=L+LW3co1; spf=pass (google.com: domain of dan.j.williams@intel.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=dan.j.williams@intel.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=AppOhepgnEe0jjnJnZQBJyzyqCwLm69rPfFkLY+t1bc=; b=L+LW3co1OBHWplV01UpK1fvt6NIcRF2qR2+gyrISeEZDbLPi91YZXqNIJExJQhxjVL 7NO7u5O4wqUQFCjZA8X/xN5IC6nTONNL0PLEmadz1t01bknVW+LPFjhIpUDlZICWj1OK Gog3pb+AQtERVqv6j7fTaoTVYFpk5W1Hfef0DgmAjMPes0MNZ9hclPMHOd3R6z/1niZy xhltfPQTbipOo4AOyWvfdtdcgObLiRuElMk7blxcxcA8+NrVrohUYIrXM1xWntr04dh1 fdyvcy8a9IUZO0qDkJUM7+nBLab/Ub+ZVWPgR39zFgOFrotnlWhaK61bEldeFuweA1TX hgpA== X-Google-Smtp-Source: APXvYqyF4/fQjVQSHjLx0TTlLSRvNfoC1XWgfZBLjCA5t1eNPRU75djqD3lZLhJzoRPj37ekmpc9LL5nqKSkBxWsIsE= X-Received: by 2002:a9d:470d:: with SMTP id a13mr36193657otf.126.1560973572970; Wed, 19 Jun 2019 12:46:12 -0700 (PDT) MIME-Version: 1.0 References: <20190613094326.24093-1-hch@lst.de> <20190613094326.24093-19-hch@lst.de> <20190613194430.GY22062@mellanox.com> <20190613195819.GA22062@mellanox.com> <20190614004314.GD783@iweiny-DESK2.sc.intel.com> <20190619192719.GO9374@mellanox.com> In-Reply-To: <20190619192719.GO9374@mellanox.com> From: Dan Williams Date: Wed, 19 Jun 2019 12:46:01 -0700 Message-ID: Subject: Re: [PATCH 18/22] mm: mark DEVICE_PUBLIC as broken To: Jason Gunthorpe Cc: John Hubbard , Ralph Campbell , "linux-nvdimm@lists.01.org" , "nouveau@lists.freedesktop.org" , "linux-kernel@vger.kernel.org" , "dri-devel@lists.freedesktop.org" , "linux-mm@kvack.org" , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Ben Skeggs , "linux-pci@vger.kernel.org" , Christoph Hellwig Content-Type: text/plain; charset="UTF-8" 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 Wed, Jun 19, 2019 at 12:42 PM Jason Gunthorpe wrote: > > On Thu, Jun 13, 2019 at 06:23:04PM -0700, John Hubbard wrote: > > On 6/13/19 5:43 PM, Ira Weiny wrote: > > > On Thu, Jun 13, 2019 at 07:58:29PM +0000, Jason Gunthorpe wrote: > > >> On Thu, Jun 13, 2019 at 12:53:02PM -0700, Ralph Campbell wrote: > > >>> > > ... > > >> Hum, so the only thing this config does is short circuit here: > > >> > > >> static inline bool is_device_public_page(const struct page *page) > > >> { > > >> return IS_ENABLED(CONFIG_DEV_PAGEMAP_OPS) && > > >> IS_ENABLED(CONFIG_DEVICE_PUBLIC) && > > >> is_zone_device_page(page) && > > >> page->pgmap->type == MEMORY_DEVICE_PUBLIC; > > >> } > > >> > > >> Which is called all over the place.. > > > > > > yes but the earlier patch: > > > > > > [PATCH 03/22] mm: remove hmm_devmem_add_resource > > > > > > Removes the only place type is set to MEMORY_DEVICE_PUBLIC. > > > > > > So I think it is ok. Frankly I was wondering if we should remove the public > > > type altogether but conceptually it seems ok. But I don't see any users of it > > > so... should we get rid of it in the code rather than turning the config off? > > > > > > Ira > > > > That seems reasonable. I recall that the hope was for those IBM Power 9 > > systems to use _PUBLIC, as they have hardware-based coherent device (GPU) > > memory, and so the memory really is visible to the CPU. And the IBM team > > was thinking of taking advantage of it. But I haven't seen anything on > > that front for a while. > > Does anyone know who those people are and can we encourage them to > send some patches? :) I expect marking it CONFIG_BROKEN with the threat of deleting it if no patches show up *is* the encouragement.