"Rafael J. Wysocki" <raf...@kernel.org> writes: > On Thu, Mar 23, 2017 at 4:22 PM, Vaidyanathan Srinivasan > <sva...@linux.vnet.ibm.com> wrote: >> 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 <sva...@linux.vnet.ibm.com> > > That needs to be ACKed by someone familiar with powernv.
Acked-by: Michael Ellerman <m...@ellerman.id.au> cheers