Hi, On 04/24/2018 10:40 AM, Stewart Smith wrote: > Shilpasri G Bhat <shilpa.b...@linux.vnet.ibm.com> writes: >> gpstate_timer_handler() uses synchronous smp_call to set the pstate >> on the requested core. This causes the below hard lockup: >> >> [c000003fe566b320] [c0000000001d5340] smp_call_function_single+0x110/0x180 >> (unreliable) >> [c000003fe566b390] [c0000000001d55e0] smp_call_function_any+0x180/0x250 >> [c000003fe566b3f0] [c000000000acd3e8] gpstate_timer_handler+0x1e8/0x580 >> [c000003fe566b4a0] [c0000000001b46b0] call_timer_fn+0x50/0x1c0 >> [c000003fe566b520] [c0000000001b4958] expire_timers+0x138/0x1f0 >> [c000003fe566b590] [c0000000001b4bf8] run_timer_softirq+0x1e8/0x270 >> [c000003fe566b630] [c000000000d0d6c8] __do_softirq+0x158/0x3e4 >> [c000003fe566b710] [c000000000114be8] irq_exit+0xe8/0x120 >> [c000003fe566b730] [c000000000024d0c] timer_interrupt+0x9c/0xe0 >> [c000003fe566b760] [c000000000009014] decrementer_common+0x114/0x120 >> --- interrupt: 901 at doorbell_global_ipi+0x34/0x50 >> LR = arch_send_call_function_ipi_mask+0x120/0x130 >> [c000003fe566ba50] [c00000000004876c] >> arch_send_call_function_ipi_mask+0x4c/0x130 (unreliable) >> [c000003fe566ba90] [c0000000001d59f0] smp_call_function_many+0x340/0x450 >> [c000003fe566bb00] [c000000000075f18] pmdp_invalidate+0x98/0xe0 >> [c000003fe566bb30] [c0000000003a1120] change_huge_pmd+0xe0/0x270 >> [c000003fe566bba0] [c000000000349278] change_protection_range+0xb88/0xe40 >> [c000003fe566bcf0] [c0000000003496c0] mprotect_fixup+0x140/0x340 >> [c000003fe566bdb0] [c000000000349a74] SyS_mprotect+0x1b4/0x350 >> [c000003fe566be30] [c00000000000b184] system_call+0x58/0x6c >> >> Fix this by using the asynchronus smp_call in the timer interrupt handler. >> We don't have to wait in this handler until the pstates are changed on >> the core. This change will not have any impact on the global pstate >> ramp-down algorithm. >> >> Reported-by: Nicholas Piggin <npig...@gmail.com> >> Reported-by: Pridhiviraj Paidipeddi <ppaid...@linux.vnet.ibm.com> >> Signed-off-by: Shilpasri G Bhat <shilpa.b...@linux.vnet.ibm.com> >> --- >> drivers/cpufreq/powernv-cpufreq.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/cpufreq/powernv-cpufreq.c >> b/drivers/cpufreq/powernv-cpufreq.c >> index 0591874..7e0c752 100644 >> --- a/drivers/cpufreq/powernv-cpufreq.c >> +++ b/drivers/cpufreq/powernv-cpufreq.c >> @@ -721,7 +721,7 @@ void gpstate_timer_handler(struct timer_list *t) >> spin_unlock(&gpstates->gpstate_lock); >> >> /* Timer may get migrated to a different cpu on cpu hot unplug */ >> - smp_call_function_any(policy->cpus, set_pstate, &freq_data, 1); >> + smp_call_function_any(policy->cpus, set_pstate, &freq_data, 0); >> } > > Should this have: > Fixes: eaa2c3aeef83f > and CC stable v4.7+ ? >
Yeah this is required. Fixes: eaa2c3aeef83 (cpufreq: powernv: Ramp-down global pstate slower than local-pstate) Thanks and Regards, Shilpa
