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Groups > linux.kernel > #1614083

Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage

From Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Newsgroups linux.kernel
Subject Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage
Date 2017-03-31 16:50 +0200
Message-ID <tr62e-5Sb-13@gated-at.bofh.it> (permalink)
References <tqif8-4VF-31@gated-at.bofh.it> <tqQ77-42d-13@gated-at.bofh.it> <tqUDL-6Xi-1@gated-at.bofh.it> <tqW2S-7VW-19@gated-at.bofh.it> <tqYxH-10x-1@gated-at.bofh.it>
Organization linux.* mail to news gateway

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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 your binary.
> >> > [   21.148898] VFS: Warning: trinity-c0 using old stat() call. Recompile your binary.
> >> > [   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'?
> 
> Yes.
> 
> >
> >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
--- a/kernel/reboot.c
+++ b/kernel/reboot.c
@@ -60,6 +60,7 @@ void (*pm_power_off_prepare)(void);
  */
 void emergency_restart(void)
 {
+	pr_emerg("Emergency restart\n");
 	kmsg_dump(KMSG_DUMP_EMERG);
 	machine_emergency_restart();
 }

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Thread

[RFC][PATCHv2 0/8] printk: introduce printing kernel thread Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-03-29 11:30 +0200
  [RFC][PATCHv2 2/8] printk: introduce printing kernel thread Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-03-29 11:30 +0200
    Re: [RFC][PATCHv2 2/8] printk: introduce printing kernel thread Petr Mladek <pmladek@suse.com> - 2017-04-04 11:10 +0200
      Re: [RFC][PATCHv2 2/8] printk: introduce printing kernel thread Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-04 11:40 +0200
    Re: [RFC][PATCHv2 2/8] printk: introduce printing kernel thread Pavel Machek <pavel@ucw.cz> - 2017-04-06 19:20 +0200
      Re: [RFC][PATCHv2 2/8] printk: introduce printing kernel thread Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-07 07:20 +0200
        Re: [RFC][PATCHv2 2/8] printk: introduce printing kernel thread Pavel Machek <pavel@ucw.cz> - 2017-04-07 09:30 +0200
          Re: [RFC][PATCHv2 2/8] printk: introduce printing kernel thread Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-07 10:20 +0200
            Re: [RFC][PATCHv2 2/8] printk: introduce printing kernel thread Pavel Machek <pavel@ucw.cz> - 2017-04-07 14:10 +0200
  [RFC][PATCHv2 5/8] sysrq: switch to printk.emergency mode in unsafe places Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-03-29 11:30 +0200
    Re: [RFC][PATCHv2 5/8] sysrq: switch to printk.emergency mode in  unsafe places Petr Mladek <pmladek@suse.com> - 2017-03-31 17:40 +0200
      Re: [RFC][PATCHv2 5/8] sysrq: switch to printk.emergency mode in  unsafe places Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-04-01 02:10 +0200
  [RFC][PATCHv2 1/8] printk: move printk_pending out of per-cpu Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-03-29 11:40 +0200
    Re: [RFC][PATCHv2 1/8] printk: move printk_pending out of per-cpu Petr Mladek <pmladek@suse.com> - 2017-03-31 15:20 +0200
      Re: [RFC][PATCHv2 1/8] printk: move printk_pending out of per-cpu Peter Zijlstra <peterz@infradead.org> - 2017-03-31 15:40 +0200
        Re: [RFC][PATCHv2 1/8] printk: move printk_pending out of per-cpu Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-03 13:30 +0200
          Re: [RFC][PATCHv2 1/8] printk: move printk_pending out of per-cpu Petr Mladek <pmladek@suse.com> - 2017-04-03 14:50 +0200
  [RFC][PATCHv2 6/8] kexec: switch to printk.emergency mode in unsafe places Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-03-29 11:40 +0200
    Re: [RFC][PATCHv2 6/8] kexec: switch to printk.emergency mode in  unsafe places Petr Mladek <pmladek@suse.com> - 2017-03-31 17:40 +0200
  [RFC][PATCHv2 8/8] printk: enable printk offloading Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-03-29 11:40 +0200
    Re: [printk]  fbc14616f4:  BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-03-31 04:40 +0200
      Re: [printk]  fbc14616f4:  BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-03-31 06:10 +0200
        Re: [printk]  fbc14616f4:  BUG:kernel_reboot-without-warning_in_test_stage Ye Xiaolong <xiaolong.ye@intel.com> - 2017-03-31 08:50 +0200
          Re: [printk]  fbc14616f4:  BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-03-31 16:50 +0200
            Re: [printk]  fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage ebiederm@xmission.com (Eric W. Biederman) - 2017-03-31 17:40 +0200
              Re: [printk]  fbc14616f4:  BUG:kernel_reboot-without-warning_in_test_stage Jan Kara <jack@suse.cz> - 2017-04-03 11:40 +0200
                Re: [printk]  fbc14616f4:  BUG:kernel_reboot-without-warning_in_test_stage Petr Mladek <pmladek@suse.com> - 2017-04-03 12:10 +0200
                Re: [printk]  fbc14616f4:  BUG:kernel_reboot-without-warning_in_test_stage Pavel Machek <pavel@ucw.cz> - 2017-04-06 19:40 +0200
                Re: [printk]  fbc14616f4:  BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-07 06:50 +0200
                Re: [printk]  fbc14616f4:  BUG:kernel_reboot-without-warning_in_test_stage Pavel Machek <pavel@ucw.cz> - 2017-04-07 09:20 +0200
                Re: [printk]  fbc14616f4:  BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-07 09:50 +0200
                Re: [printk]  fbc14616f4:  BUG:kernel_reboot-without-warning_in_test_stage Pavel Machek <pavel@ucw.cz> - 2017-04-07 10:20 +0200
                Re: [printk]  fbc14616f4:  BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-07 14:20 +0200
                Re: [printk]  fbc14616f4:  BUG:kernel_reboot-without-warning_in_test_stage Pavel Machek <pavel@ucw.cz> - 2017-04-07 14:50 +0200
                Re: [printk]  fbc14616f4:  BUG:kernel_reboot-without-warning_in_test_stage Steven Rostedt <rostedt@goodmis.org> - 2017-04-07 16:50 +0200
                Re: [printk]  fbc14616f4:  BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-04-07 17:20 +0200
                Re: [printk]  fbc14616f4:  BUG:kernel_reboot-without-warning_in_test_stage Peter Zijlstra <peterz@infradead.org> - 2017-04-07 17:30 +0200
                Re: [printk]  fbc14616f4:  BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-04-07 17:50 +0200
                Re: [printk]  fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage ebiederm@xmission.com (Eric W. Biederman) - 2017-04-09 20:30 +0200
                Re: [printk]  fbc14616f4:  BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-10 06:50 +0200
                Re: [printk]  fbc14616f4:  BUG:kernel_reboot-without-warning_in_test_stage Pavel Machek <pavel@ucw.cz> - 2017-04-09 12:20 +0200
                Re: [printk]  fbc14616f4:  BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-10 07:00 +0200
                Re: [printk]  fbc14616f4:  BUG:kernel_reboot-without-warning_in_test_stage Petr Mladek <pmladek@suse.com> - 2017-04-10 14:00 +0200
                Re: [printk]  fbc14616f4:  BUG:kernel_reboot-without-warning_in_test_stage Steven Rostedt <rostedt@goodmis.org> - 2017-04-07 16:40 +0200
                Re: [printk]  fbc14616f4:  BUG:kernel_reboot-without-warning_in_test_stage Pavel Machek <pavel@ucw.cz> - 2017-04-09 12:00 +0200
              Re: [printk]  fbc14616f4:  BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-03 13:00 +0200
          Re: [printk]  fbc14616f4:  BUG:kernel_reboot-without-warning_in_test_stage Ye Xiaolong <xiaolong.ye@intel.com> - 2017-04-05 09:40 +0200
            Re: [printk]  fbc14616f4:  BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-05 10:50 +0200
    Re: [RFC][PATCHv2 8/8] printk: enable printk offloading Petr Mladek <pmladek@suse.com> - 2017-04-03 17:50 +0200
      Re: [RFC][PATCHv2 8/8] printk: enable printk offloading Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-04-04 14:30 +0200
  [RFC][PATCHv2 4/8] pm: switch to printk.emergency mode in unsafe places Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-03-29 11:40 +0200
    Re: [RFC][PATCHv2 4/8] pm: switch to printk.emergency mode in unsafe  places Petr Mladek <pmladek@suse.com> - 2017-03-31 17:10 +0200
    Re: [RFC][PATCHv2 4/8] pm: switch to printk.emergency mode in unsafe  places Pavel Machek <pavel@ucw.cz> - 2017-04-06 19:30 +0200
      Re: [RFC][PATCHv2 4/8] pm: switch to printk.emergency mode in unsafe  places Andreas Mohr <andi@lisas.de> - 2017-04-09 13:00 +0200
        Re: [RFC][PATCHv2 4/8] pm: switch to printk.emergency mode in unsafe  places Petr Mladek <pmladek@suse.com> - 2017-04-10 14:30 +0200
          Re: [RFC][PATCHv2 4/8] pm: switch to printk.emergency mode in unsafe  places Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-04-10 16:40 +0200
  [RFC][PATCHv2 7/8] printk: add printk emergency_mode parameter Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-03-29 11:40 +0200
    Re: [RFC][PATCHv2 7/8] printk: add printk emergency_mode parameter Petr Mladek <pmladek@suse.com> - 2017-04-03 17:30 +0200
      Re: [RFC][PATCHv2 7/8] printk: add printk emergency_mode parameter Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-04 10:30 +0200

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