From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3vpr1f4rLxzDq5g for ; Fri, 24 Mar 2017 02:24:06 +1100 (AEDT) Received: from pps.filterd (m0098399.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v2NFNoYU042349 for ; Thu, 23 Mar 2017 11:24:01 -0400 Received: from e23smtp02.au.ibm.com (e23smtp02.au.ibm.com [202.81.31.144]) by mx0a-001b2d01.pphosted.com with ESMTP id 29c57ed2j4-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Thu, 23 Mar 2017 11:24:01 -0400 Received: from localhost by e23smtp02.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 24 Mar 2017 01:23:58 +1000 Received: from d23av02.au.ibm.com (d23av02.au.ibm.com [9.190.235.138]) by d23relay08.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v2NFNmF927721800 for ; Fri, 24 Mar 2017 02:23:56 +1100 Received: from d23av02.au.ibm.com (localhost [127.0.0.1]) by d23av02.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id v2NFNLRf015155 for ; Fri, 24 Mar 2017 02:23:22 +1100 From: Vaidyanathan Srinivasan To: Michael Neuling , Michael Ellerman , "Rafael J . Wysocki" , Daniel Lezcano Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org Subject: [PATCH v2 1/2] powerpc/powernv/cpuidle: Pass correct drv->cpumask for registration Date: Thu, 23 Mar 2017 20:52:46 +0530 In-Reply-To: <20170323152247.14733-1-svaidy@linux.vnet.ibm.com> References: <20170323152247.14733-1-svaidy@linux.vnet.ibm.com> Message-Id: <20170323152247.14733-2-svaidy@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , drv->cpumask defaults to cpu_possible_mask in __cpuidle_driver_init(). On PowerNV platform cpu_present could be less than cpu_possible in cases where firmware detects the cpu, but it is not available to the OS. When CONFIG_HOTPLUG_CPU=n, such cpus are not hotplugable at runtime and hence we skip creating cpu_device. This breaks cpuidle on powernv where register_cpu() is not called for cpus in cpu_possible_mask that cannot be hot-added at runtime. Trying cpuidle_register_device() on cpu without cpu_device will cause crash like this: cpu 0xf: Vector: 380 (Data SLB Access) at [c000000ff1503490] pc: c00000000022c8bc: string+0x34/0x60 lr: c00000000022ed78: vsnprintf+0x284/0x42c sp: c000000ff1503710 msr: 9000000000009033 dar: 6000000060000000 current = 0xc000000ff1480000 paca = 0xc00000000fe82d00 softe: 0 irq_happened: 0x01 pid = 1, comm = swapper/8 Linux version 4.11.0-rc2 (sv@sagarika) (gcc version 4.9.4 (Buildroot 2017.02-00004-gc28573e) ) #15 SMP Fri Mar 17 19:32:02 IST 2017 enter ? for help [link register ] c00000000022ed78 vsnprintf+0x284/0x42c [c000000ff1503710] c00000000022ebb8 vsnprintf+0xc4/0x42c (unreliable) [c000000ff1503800] c00000000022ef40 vscnprintf+0x20/0x44 [c000000ff1503830] c0000000000ab61c vprintk_emit+0x94/0x2cc [c000000ff15038a0] c0000000000acc9c vprintk_func+0x60/0x74 [c000000ff15038c0] c000000000619694 printk+0x38/0x4c [c000000ff15038e0] c000000000224950 kobject_get+0x40/0x60 [c000000ff1503950] c00000000022507c kobject_add_internal+0x60/0x2c4 [c000000ff15039e0] c000000000225350 kobject_init_and_add+0x70/0x78 [c000000ff1503a60] c00000000053c288 cpuidle_add_sysfs+0x9c/0xe0 [c000000ff1503ae0] c00000000053aeac cpuidle_register_device+0xd4/0x12c [c000000ff1503b30] c00000000053b108 cpuidle_register+0x98/0xcc [c000000ff1503bc0] c00000000085eaf0 powernv_processor_idle_init+0x140/0x1e0 [c000000ff1503c60] c00000000000cd60 do_one_initcall+0xc0/0x15c [c000000ff1503d20] c000000000833e84 kernel_init_freeable+0x1a0/0x25c [c000000ff1503dc0] c00000000000d478 kernel_init+0x24/0x12c [c000000ff1503e30] c00000000000b564 ret_from_kernel_thread+0x5c/0x78 This patch fixes the bug by passing correct cpumask from powernv-cpuidle driver. Signed-off-by: Vaidyanathan Srinivasan --- drivers/cpuidle/cpuidle-powernv.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/drivers/cpuidle/cpuidle-powernv.c b/drivers/cpuidle/cpuidle-powernv.c index a06df51..82f7b33 100644 --- a/drivers/cpuidle/cpuidle-powernv.c +++ b/drivers/cpuidle/cpuidle-powernv.c @@ -175,6 +175,24 @@ static int powernv_cpuidle_driver_init(void) drv->state_count += 1; } + /* + * On PowerNV platform cpu_present may be less that cpu_possible in + * cases where firmware detects the cpu, but it is not available to the + * OS. If CONFIG_HOTPLUG_CPU=n then such CPUs are not hotplugable at + * runtime and hence cpu_devices are not created for those cpus by + * generic topology_init(). + * + * drv->cpumask defaults to cpu_possible_mask in + * __cpuidle_driver_init(). This breaks cpuidle on powernv where + * cpu_devices are not created for cpus in cpu_possible_mask that + * cannot be hot-added later at runtime. + * + * Trying cpuidle_register_device() on a cpu without cpu_devices is + * incorrect. Hence pass correct cpu mask to generic cpuidle driver. + */ + + drv->cpumask = (struct cpumask *)cpu_present_mask; + return 0; } -- 2.9.3