On (03/31/17 14:39), Ye Xiaolong wrote:
On 03/31, Sergey Senozhatsky wrote:
>On (03/31/17 11:35), Sergey Senozhatsky wrote:
>> > [ 21.009531] VFS: Warning: trinity-c2 using old stat() call. Recompile
>> > [ 21.148898] VFS: Warning: trinity-c0 using old stat() call. Recompile
>> > [ 22.298208] warning: process `trinity-c2' used the deprecated sysctl
system call with
>> > Elapsed time: 310
>> > BUG: kernel reboot-without-warning in test stage
>> so as far as I understand, this is the "missing kernel messages"
>> type of bug report. a worst case scenario.
>panic() should have called console_flush_on_panic(), which sould have
>flushed the messages regardless the printk_kthread state. so it probably
>was not panic() that rebooted the kernel. (probably).
>kernel_restart() and kernel_halt() have pr_emerg() messages, printk switches
>to printk_emergency mode the first time it sees EMERG level message. (may be
>we switch to late).
>on the other hand, there is a emergency_restart(), where we don't switch
>to printk_emergency mode and don't flush the existing kernel messages.
>there is a bunch of places that call emergency_restart(), including sysrq.
>may I ask you, how do you usually restart the vm after the test?
>`echo X > /proc/sysrq-trigger'?
>does this patch make it any better?
I am trying it and will post the result once I get it.
... I'd also probably add pr_emerg() print-out to emergency_restart(),
the same way kernel_restart()/kernel_halt()/kernel_power_off() do.
for those cases when emergency_restart() is called with printk in
kthreaded mode, not in emergency mode.
diff --git a/kernel/reboot.c b/kernel/reboot.c
index e4ced883d8de..5bce29da913b 100644
@@ -60,6 +60,7 @@ void (*pm_power_off_prepare)(void);
+ pr_emerg("Emergency restart\n");