From patchwork Mon Feb 25 18:57:36 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dave Hansen X-Patchwork-Id: 10829029 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id F0B5B1390 for ; Mon, 25 Feb 2019 19:02:42 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id DF6252B7CC for ; Mon, 25 Feb 2019 19:02:42 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D3BCC2B7D5; Mon, 25 Feb 2019 19:02:42 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 63CD12B7CC for ; Mon, 25 Feb 2019 19:02:42 +0000 (UTC) Received: from [127.0.0.1] (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 5976A211CF36E; Mon, 25 Feb 2019 11:02:42 -0800 (PST) X-Original-To: linux-nvdimm@lists.01.org Delivered-To: linux-nvdimm@lists.01.org Received-SPF: None (no SPF record) identity=mailfrom; client-ip=134.134.136.31; helo=mga06.intel.com; envelope-from=dave.hansen@linux.intel.com; receiver=linux-nvdimm@lists.01.org Received: from mga06.intel.com (mga06.intel.com [134.134.136.31]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 001DA211CF36A for ; Mon, 25 Feb 2019 11:02:40 -0800 (PST) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 25 Feb 2019 11:02:40 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.58,412,1544515200"; d="scan'208";a="302443100" Received: from viggo.jf.intel.com (HELO localhost.localdomain) ([10.54.77.144]) by orsmga005.jf.intel.com with ESMTP; 25 Feb 2019 11:02:40 -0800 Subject: [PATCH 3/5] mm/memory-hotplug: allow memory resources to be children To: linux-kernel@vger.kernel.org From: Dave Hansen Date: Mon, 25 Feb 2019 10:57:36 -0800 References: <20190225185727.BCBD768C@viggo.jf.intel.com> In-Reply-To: <20190225185727.BCBD768C@viggo.jf.intel.com> Message-Id: <20190225185736.7B4711BC@viggo.jf.intel.com> X-BeenThere: linux-nvdimm@lists.01.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Linux-nvdimm developer list." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: thomas.lendacky@amd.com, mhocko@suse.com, linux-nvdimm@lists.01.org, tiwai@suse.de, Dave Hansen , ying.huang@intel.com, linux-mm@kvack.org, jglisse@redhat.com, bp@suse.de, baiyaowei@cmss.chinamobile.com, zwisler@kernel.org, bhelgaas@google.com, fengguang.wu@intel.com, akpm@linux-foundation.org MIME-Version: 1.0 Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" X-Virus-Scanned: ClamAV using ClamSMTP From: Dave Hansen The mm/resource.c code is used to manage the physical address space. The current resource configuration can be viewed in /proc/iomem. An example of this is at the bottom of this description. The nvdimm subsystem "owns" the physical address resources which map to persistent memory and has resources inserted for them as "Persistent Memory". The best way to repurpose this for volatile use is to leave the existing resource in place, but add a "System RAM" resource underneath it. This clearly communicates the ownership relationship of this memory. The request_resource_conflict() API only deals with the top-level resources. Replace it with __request_region() which will search for !IORESOURCE_BUSY areas lower in the resource tree than the top level. We *could* also simply truncate the existing top-level "Persistent Memory" resource and take over the released address space. But, this means that if we ever decide to hot-unplug the "RAM" and give it back, we need to recreate the original setup, which may mean going back to the BIOS tables. This should have no real effect on the existing collision detection because the areas that truly conflict should be marked IORESOURCE_BUSY. 00000000-00000fff : Reserved 00001000-0009fbff : System RAM 0009fc00-0009ffff : Reserved 000a0000-000bffff : PCI Bus 0000:00 000c0000-000c97ff : Video ROM 000c9800-000ca5ff : Adapter ROM 000f0000-000fffff : Reserved 000f0000-000fffff : System ROM 00100000-9fffffff : System RAM 01000000-01e071d0 : Kernel code 01e071d1-027dfdff : Kernel data 02dc6000-0305dfff : Kernel bss a0000000-afffffff : Persistent Memory (legacy) a0000000-a7ffffff : System RAM b0000000-bffdffff : System RAM bffe0000-bfffffff : Reserved c0000000-febfffff : PCI Bus 0000:00 Signed-off-by: Dave Hansen Reviewed-by: Dan Williams Reviewed-by: Vishal Verma Cc: Dave Jiang Cc: Ross Zwisler Cc: Vishal Verma Cc: Tom Lendacky Cc: Andrew Morton Cc: Michal Hocko Cc: linux-nvdimm@lists.01.org Cc: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org Cc: Huang Ying Cc: Fengguang Wu Cc: Borislav Petkov Cc: Bjorn Helgaas Cc: Yaowei Bai Cc: Takashi Iwai Cc: Jerome Glisse Cc: Keith Busch --- b/mm/memory_hotplug.c | 26 ++++++++++++++------------ 1 file changed, 14 insertions(+), 12 deletions(-) diff -puN mm/memory_hotplug.c~mm-memory-hotplug-allow-memory-resource-to-be-child mm/memory_hotplug.c --- a/mm/memory_hotplug.c~mm-memory-hotplug-allow-memory-resource-to-be-child 2019-02-25 10:56:49.707908029 -0800 +++ b/mm/memory_hotplug.c 2019-02-25 10:56:49.711908029 -0800 @@ -100,19 +100,21 @@ void mem_hotplug_done(void) /* add this memory to iomem resource */ static struct resource *register_memory_resource(u64 start, u64 size) { - struct resource *res, *conflict; - res = kzalloc(sizeof(struct resource), GFP_KERNEL); - if (!res) - return ERR_PTR(-ENOMEM); + struct resource *res; + unsigned long flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY; + char *resource_name = "System RAM"; - res->name = "System RAM"; - res->start = start; - res->end = start + size - 1; - res->flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY; - conflict = request_resource_conflict(&iomem_resource, res); - if (conflict) { - pr_debug("System RAM resource %pR cannot be added\n", res); - kfree(res); + /* + * Request ownership of the new memory range. This might be + * a child of an existing resource that was present but + * not marked as busy. + */ + res = __request_region(&iomem_resource, start, size, + resource_name, flags); + + if (!res) { + pr_debug("Unable to reserve System RAM region: %016llx->%016llx\n", + start, start + size); return ERR_PTR(-EEXIST); } return res;