From patchwork Wed Jan 6 22:30:00 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Allen X-Patchwork-Id: 564123 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 82807140213 for ; Thu, 7 Jan 2016 09:31:31 +1100 (AEDT) Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 6B2B11A15DF for ; Thu, 7 Jan 2016 09:31:31 +1100 (AEDT) X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Received: from e32.co.us.ibm.com (e32.co.us.ibm.com [32.97.110.150]) (using TLSv1 with cipher CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4F6471A029B for ; Thu, 7 Jan 2016 09:30:35 +1100 (AEDT) Received: from localhost by e32.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 6 Jan 2016 15:30:31 -0700 Received: from d03dlp02.boulder.ibm.com (9.17.202.178) by e32.co.us.ibm.com (192.168.1.132) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; Wed, 6 Jan 2016 15:30:05 -0700 X-IBM-Helo: d03dlp02.boulder.ibm.com X-IBM-MailFrom: jallen@linux.vnet.ibm.com X-IBM-RcptTo: linuxppc-dev@lists.ozlabs.org Received: from b01cxnp23032.gho.pok.ibm.com (b01cxnp23032.gho.pok.ibm.com [9.57.198.27]) by d03dlp02.boulder.ibm.com (Postfix) with ESMTP id 7773C3E40044 for ; Wed, 6 Jan 2016 15:30:04 -0700 (MST) Received: from d01av01.pok.ibm.com (d01av01.pok.ibm.com [9.56.224.215]) by b01cxnp23032.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u06MU4KH25493504 for ; Wed, 6 Jan 2016 22:30:04 GMT Received: from d01av01.pok.ibm.com (localhost [127.0.0.1]) by d01av01.pok.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u06MU3gj025322 for ; Wed, 6 Jan 2016 17:30:03 -0500 Received: from [9.80.33.232] ([9.80.33.232]) by d01av01.pok.ibm.com (8.14.4/8.14.4/NCO v10.0 AVin) with ESMTP id u06MU0Ro024923; Wed, 6 Jan 2016 17:30:01 -0500 From: John Allen Subject: [PATCH v4] memory-hotplug: Fix kernel warning during memory hotplug on ppc64 To: gregkh@linuxfoundation.org Message-ID: <568D9568.1010808@linux.vnet.ibm.com> Date: Wed, 6 Jan 2016 16:30:00 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16010622-0005-0000-0000-00001B3229B7 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Nathan Fontenot , akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" This patch fixes a bug where a kernel warning is triggered when performing a memory hotplug on ppc64. This warning may also occur on any architecture that uses the memory_probe_store interface. WARNING: at drivers/base/memory.c:200 CPU: 9 PID: 13042 Comm: systemd-udevd Not tainted 4.4.0-rc4-00113-g0bd0f1e-dirty #7 NIP [c00000000055e034] pages_correctly_reserved+0x134/0x1b0 LR [c00000000055e7f8] memory_subsys_online+0x68/0x140 Call Trace: [c0000000fa9e7b50] [c0000000fa9e7b90] 0xc0000000fa9e7b90 (unreliable) [c0000000fa9e7bb0] [c00000000055e7f8] memory_subsys_online+0x68/0x140 [c0000000fa9e7bf0] [c000000000540064] device_online+0xb4/0x120 [c0000000fa9e7c30] [c00000000055e6c0] store_mem_state+0xb0/0x180 [c0000000fa9e7c70] [c00000000053c5e4] dev_attr_store+0x34/0x60 [c0000000fa9e7c90] [c0000000002db0a4] sysfs_kf_write+0x64/0xa0 [c0000000fa9e7cb0] [c0000000002da0cc] kernfs_fop_write+0x17c/0x1e0 [c0000000fa9e7d00] [c0000000002481b0] __vfs_write+0x40/0x160 [c0000000fa9e7d90] [c000000000248ce8] vfs_write+0xb8/0x200 [c0000000fa9e7de0] [c000000000249b40] SyS_write+0x60/0x110 [c0000000fa9e7e30] [c000000000009260] system_call+0x38/0xd0 The warning is triggered because there is a udev rule that automatically tries to online memory after it has been added. The udev rule varies from distro to distro, but will generally look something like: SUBSYSTEM=="memory", ACTION=="add", ATTR{state}=="offline", ATTR{state}="online" On any architecture that uses memory_probe_store to reserve memory, the udev rule will be triggered after the first section of the block is reserved and will subsequently attempt to online the entire block, interrupting the memory reservation process and causing the warning. This patch modifies memory_probe_store to add a block of memory with a single call to add_memory as opposed to looping through and adding each section individually. A single call to add_memory is protected by the mem_hotplug mutex which will prevent the udev rule from onlining memory until the reservation of the entire block is complete. Signed-off-by: John Allen Acked-by: Dave Hansen --- v2: -Move call to unlock_device_hotplug under "out" label v3: -Update changelog with trimmed traces from newer kernel -After further testing and reviewing the original purpose of the lock_device_hotplug_sysfs mutex, modified solution to fix the issue by replacing loop that adds memory section by section with a single call to add_memory. v4: -Remove unused variable 'i' diff --git a/drivers/base/memory.c b/drivers/base/memory.c index 25425d3..e5c6ff0 100644 --- a/drivers/base/memory.c +++ b/drivers/base/memory.c @@ -450,8 +450,7 @@ memory_probe_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { u64 phys_addr; - int nid; - int i, ret; + int nid, ret; unsigned long pages_per_block = PAGES_PER_SECTION * sections_per_block; ret = kstrtoull(buf, 0, &phys_addr); @@ -461,15 +460,12 @@ memory_probe_store(struct device *dev, struct device_attribute *attr, if (phys_addr & ((pages_per_block << PAGE_SHIFT) - 1)) return -EINVAL; - for (i = 0; i < sections_per_block; i++) { - nid = memory_add_physaddr_to_nid(phys_addr); - ret = add_memory(nid, phys_addr, - PAGES_PER_SECTION << PAGE_SHIFT); - if (ret) - goto out; + nid = memory_add_physaddr_to_nid(phys_addr); + ret = add_memory(nid, phys_addr, + MIN_MEMORY_BLOCK_SIZE * sections_per_block); - phys_addr += MIN_MEMORY_BLOCK_SIZE; - } + if (ret) + goto out; ret = count; out: