From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753494AbdLMCAL (ORCPT ); Tue, 12 Dec 2017 21:00:11 -0500 Received: from fldsmtpe03.verizon.com ([140.108.26.142]:46399 "EHLO fldsmtpe03.verizon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753308AbdLMB7F (ORCPT ); Tue, 12 Dec 2017 20:59:05 -0500 From: alexander.levin@verizon.com Cc: Vaidyanathan Srinivasan , "Rafael J . Wysocki" , alexander.levin@verizon.com X-Host: endeavour.tdc.vzwcorp.com To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" Subject: [PATCH AUTOSEL for 4.9 067/100] cpuidle: powernv: Pass correct drv->cpumask for registration Thread-Topic: [PATCH AUTOSEL for 4.9 067/100] cpuidle: powernv: Pass correct drv->cpumask for registration Thread-Index: AQHTc7XBC4MN7ph1jk+qNuBfc0E9Aw== Date: Wed, 13 Dec 2017 01:57:39 +0000 Message-ID: <20171213015722.6722-42-alexander.levin@verizon.com> References: <20171213015722.6722-1-alexander.levin@verizon.com> In-Reply-To: <20171213015722.6722-1-alexander.levin@verizon.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-messagesentrepresentingtype: 1 x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.144.60.250] Content-Type: text/plain; charset="iso-8859-1" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nfs id vBD20G6i015221 From: Vaidyanathan Srinivasan [ Upstream commit 293d264f13cbde328d5477f49e3103edbc1dc191 ] 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 Reviewed-by: Gautham R. Shenoy Acked-by: Michael Ellerman [ rjw: Comment massage ] Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin --- 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 7fe442ca38f4..854a56781100 100644 --- a/drivers/cpuidle/cpuidle-powernv.c +++ b/drivers/cpuidle/cpuidle-powernv.c @@ -164,6 +164,24 @@ static int powernv_cpuidle_driver_init(void) drv->state_count += 1; } + /* + * On the PowerNV platform cpu_present may be less than cpu_possible in + * cases when firmware detects the CPU, but it is not available to the + * OS. If CONFIG_HOTPLUG_CPU=n, then such CPUs are not hotplugable at + * run time and hence cpu_devices are not created for those CPUs by the + * 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 run time. + * + * Trying cpuidle_register_device() on a CPU without a cpu_device is + * incorrect, so pass a correct CPU mask to the generic cpuidle driver. + */ + + drv->cpumask = (struct cpumask *)cpu_present_mask; + return 0; } -- 2.11.0