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[192.55.52.43]) by mx.google.com with ESMTPS id q24si23382216pls.325.2019.01.24.15.21.53 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 24 Jan 2019 15:21:54 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of dave.hansen@linux.intel.com designates 192.55.52.43 as permitted sender) client-ip=192.55.52.43; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of dave.hansen@linux.intel.com designates 192.55.52.43 as permitted sender) smtp.mailfrom=dave.hansen@linux.intel.com; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=intel.com X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 24 Jan 2019 15:21:53 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,518,1539673200"; d="scan'208";a="294207413" Received: from viggo.jf.intel.com (HELO localhost.localdomain) ([10.54.77.144]) by orsmga005.jf.intel.com with ESMTP; 24 Jan 2019 15:21:53 -0800 Subject: [PATCH 2/5] mm/resource: move HMM pr_debug() deeper into resource code To: linux-kernel@vger.kernel.org Cc: Dave Hansen ,dan.j.williams@intel.com,dave.jiang@intel.com,zwisler@kernel.org,vishal.l.verma@intel.com,thomas.lendacky@amd.com,akpm@linux-foundation.org,mhocko@suse.com,linux-nvdimm@lists.01.org,linux-mm@kvack.org,ying.huang@intel.com,fengguang.wu@intel.com,jglisse@redhat.com From: Dave Hansen Date: Thu, 24 Jan 2019 15:14:44 -0800 References: <20190124231441.37A4A305@viggo.jf.intel.com> In-Reply-To: <20190124231441.37A4A305@viggo.jf.intel.com> Message-Id: <20190124231444.38182DD8@viggo.jf.intel.com> 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: X-Virus-Scanned: ClamAV using ClamSMTP From: Dave Hansen HMM consumes physical address space for its own use, even though nothing is mapped or accessible there. It uses a special resource description (IORES_DESC_DEVICE_PRIVATE_MEMORY) to uniquely identify these areas. When HMM consumes address space, it makes a best guess about what to consume. However, it is possible that a future memory or device hotplug can collide with the reserved area. In the case of these conflicts, there is an error message in register_memory_resource(). Later patches in this series move register_memory_resource() from using request_resource_conflict() to __request_region(). Unfortunately, __request_region() does not return the conflict like the previous function did, which makes it impossible to check for IORES_DESC_DEVICE_PRIVATE_MEMORY in a conflicting resource. Instead of warning in register_memory_resource(), move the check into the core resource code itself (__request_region()) where the conflicting resource _is_ available. This has the added bonus of producing a warning in case of HMM conflicts with devices *or* RAM address space, as opposed to the RAM- only warnings that were there previously. Signed-off-by: Dave Hansen Cc: Dan Williams 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: Jerome Glisse Reviewed-by: Jerome Glisse --- b/kernel/resource.c | 10 ++++++++++ b/mm/memory_hotplug.c | 5 ----- 2 files changed, 10 insertions(+), 5 deletions(-) diff -puN kernel/resource.c~move-request_region-check kernel/resource.c --- a/kernel/resource.c~move-request_region-check 2019-01-24 15:13:14.453199539 -0800 +++ b/kernel/resource.c 2019-01-24 15:13:14.458199539 -0800 @@ -1123,6 +1123,16 @@ struct resource * __request_region(struc conflict = __request_resource(parent, res); if (!conflict) break; + /* + * mm/hmm.c reserves physical addresses which then + * become unavailable to other users. Conflicts are + * not expected. Be verbose if one is encountered. + */ + if (conflict->desc == IORES_DESC_DEVICE_PRIVATE_MEMORY) { + pr_debug("Resource conflict with unaddressable " + "device memory at %#010llx !\n", + (unsigned long long)start); + } if (conflict != parent) { if (!(conflict->flags & IORESOURCE_BUSY)) { parent = conflict; diff -puN mm/memory_hotplug.c~move-request_region-check mm/memory_hotplug.c --- a/mm/memory_hotplug.c~move-request_region-check 2019-01-24 15:13:14.455199539 -0800 +++ b/mm/memory_hotplug.c 2019-01-24 15:13:14.459199539 -0800 @@ -109,11 +109,6 @@ static struct resource *register_memory_ res->flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY; conflict = request_resource_conflict(&iomem_resource, res); if (conflict) { - if (conflict->desc == IORES_DESC_DEVICE_PRIVATE_MEMORY) { - pr_debug("Device unaddressable memory block " - "memory hotplug at %#010llx !\n", - (unsigned long long)start); - } pr_debug("System RAM resource %pR cannot be added\n", res); kfree(res); return ERR_PTR(-EEXIST);