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 1d3f9313c02f..8bfb97d07d10 100644 --- a/arch/powerpc/platforms/pseries/hotplug-cpu.c +++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c @@ -95,9 +95,6 @@ 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");