| From 324bd482deb5d1614d6967a71a279b9985533507 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Sun, 18 Apr 2021 23:54:13 +1000 |
| Subject: powerpc/pseries: Stop calling printk in rtas_stop_self() |
| |
| From: Michael Ellerman <mpe@ellerman.id.au> |
| |
| [ Upstream commit ed8029d7b472369a010a1901358567ca3b6dbb0d ] |
| |
| RCU complains about us calling printk() from an offline CPU: |
| |
| ============================= |
| WARNING: suspicious RCU usage |
| 5.12.0-rc7-02874-g7cf90e481cb8 #1 Not tainted |
| ----------------------------- |
| kernel/locking/lockdep.c:3568 RCU-list traversed in non-reader section!! |
| |
| other info that might help us debug this: |
| |
| RCU used illegally from offline CPU! |
| rcu_scheduler_active = 2, debug_locks = 1 |
| no locks held by swapper/0/0. |
| |
| stack backtrace: |
| CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.12.0-rc7-02874-g7cf90e481cb8 #1 |
| Call Trace: |
| dump_stack+0xec/0x144 (unreliable) |
| lockdep_rcu_suspicious+0x124/0x144 |
| __lock_acquire+0x1098/0x28b0 |
| lock_acquire+0x128/0x600 |
| _raw_spin_lock_irqsave+0x6c/0xc0 |
| down_trylock+0x2c/0x70 |
| __down_trylock_console_sem+0x60/0x140 |
| vprintk_emit+0x1a8/0x4b0 |
| vprintk_func+0xcc/0x200 |
| printk+0x40/0x54 |
| pseries_cpu_offline_self+0xc0/0x120 |
| arch_cpu_idle_dead+0x54/0x70 |
| do_idle+0x174/0x4a0 |
| cpu_startup_entry+0x38/0x40 |
| rest_init+0x268/0x388 |
| start_kernel+0x748/0x790 |
| start_here_common+0x1c/0x614 |
| |
| Which happens because by the time we get to rtas_stop_self() we are |
| already offline. In addition the message can be spammy, and is not that |
| helpful for users, so remove it. |
| |
| Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> |
| Link: https://lore.kernel.org/r/20210418135413.1204031-1-mpe@ellerman.id.au |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| arch/powerpc/platforms/pseries/hotplug-cpu.c | 3 --- |
| 1 file changed, 3 deletions(-) |
| |
| diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c |
| index 12cbffd3c2e3..325f3b220f36 100644 |
| --- a/arch/powerpc/platforms/pseries/hotplug-cpu.c |
| +++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c |
| @@ -47,9 +47,6 @@ static void rtas_stop_self(void) |
| |
| BUG_ON(rtas_stop_self_token == RTAS_UNKNOWN_SERVICE); |
| |
| - printk("cpu %u (hwid %u) Ready to die...\n", |
| - smp_processor_id(), hard_smp_processor_id()); |
| - |
| rtas_call_unlocked(&args, rtas_stop_self_token, 0, 1, NULL); |
| |
| panic("Alas, I survived.\n"); |
| -- |
| 2.30.2 |
| |
