| From foo@baz Thu Dec 21 09:02:40 CET 2017 |
| From: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> |
| Date: Thu, 23 Mar 2017 20:52:46 +0530 |
| Subject: cpuidle: powernv: Pass correct drv->cpumask for registration |
| |
| From: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> |
| |
| |
| [ 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 <svaidy@linux.vnet.ibm.com> |
| Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com> |
| Acked-by: Michael Ellerman <mpe@ellerman.id.au> |
| [ rjw: Comment massage ] |
| Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> |
| |
| Signed-off-by: Sasha Levin <alexander.levin@verizon.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| drivers/cpuidle/cpuidle-powernv.c | 18 ++++++++++++++++++ |
| 1 file changed, 18 insertions(+) |
| |
| --- a/drivers/cpuidle/cpuidle-powernv.c |
| +++ b/drivers/cpuidle/cpuidle-powernv.c |
| @@ -164,6 +164,24 @@ static int powernv_cpuidle_driver_init(v |
| 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; |
| } |
| |