Hi Andrew, Thanks for the review!
On Thu, Feb 28, 2019 at 12:00:14PM -0800, Andrew Morton wrote: > On Fri, 22 Feb 2019 14:09:59 +0800 Feng Tang <feng.t...@intel.com> wrote: > > > When kernel panic happens, it will first print the panic call stack, > > then the ending msg like: > > > > [ 35.743249] ---[ end Kernel panic - not syncing: Fatal exception > > [ 35.749975] ------------[ cut here ]------------ > > > > The above message are very useful for debugging. > > > > But if system is configured to not reboot on panic, say the "panic_timeout" > > parameter equals 0, it will likely print out many noisy message like > > WARN() call stack for each and every CPU except the panic one, messages > > like below: > > > > WARNING: CPU: 1 PID: 280 at kernel/sched/core.c:1198 > > set_task_cpu+0x183/0x190 > > Call Trace: > > <IRQ> > > try_to_wake_up > > default_wake_function > > autoremove_wake_function > > __wake_up_common > > __wake_up_common_lock > > __wake_up > > wake_up_klogd_work_func > > irq_work_run_list > > irq_work_tick > > update_process_times > > tick_sched_timer > > __hrtimer_run_queues > > hrtimer_interrupt > > smp_apic_timer_interrupt > > apic_timer_interrupt > > It's a fairly ugly-looking patch but I am inclined to agree. Yes, it's ugly :) we've changed 3 methods to tackle this. > The panicing CPU is spinning and blinking a LED and all CPUs have > interrupts enabled and the system is known to be in a messed up state. > All sorts of kernel code could emit all sorts of output in such > circumstances. So a global printk-killing knob seems appropriate. > > Thoughts: > > - why do the suppression in vprintk_emit()? Doing it right at entry > to printk() seems cleaner, more explicit? Yes, I put it in printk() in one earlier post, and Petr suggested to put it into vprintk_emit so that it works for all printk() interfaces, like the devkmsg_write -> printk_emit -> vprintk_emit path. > > - Other code sites may wish to suppress all printks. Perhaps > `panic_suppress_printk' should just be called `suppress_printk'? Ok, then I'll move the definition from panic.c to printk code. Thanks, Feng
