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Date: Tue, 24 Apr 2018 10:11:46 +0530 From: Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com> To: rjw@...ysocki.net, viresh.kumar@...aro.org Cc: npiggin@...il.com, benh@...nel.crashing.org, mpe@...erman.id.au, linux-pm@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org, ppaidipe@...ux.vnet.ibm.com, svaidy@...ux.vnet.ibm.com, Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com> Subject: [PATCH] cpufreq: powernv: Fix the hardlockup by synchronus smp_call in timer interrupt 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 <npiggin@...il.com> Reported-by: Pridhiviraj Paidipeddi <ppaidipe@...ux.vnet.ibm.com> Signed-off-by: Shilpasri G Bhat <shilpa.bhat@...ux.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); } /* -- 1.8.3.1
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