From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750983AbdCaEEm (ORCPT ); Fri, 31 Mar 2017 00:04:42 -0400 Received: from mail-pg0-f66.google.com ([74.125.83.66]:35781 "EHLO mail-pg0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750748AbdCaEEk (ORCPT ); Fri, 31 Mar 2017 00:04:40 -0400 Date: Fri, 31 Mar 2017 13:04:38 +0900 From: Sergey Senozhatsky To: kernel test robot Cc: Sergey Senozhatsky , Steven Rostedt , Petr Mladek , Jan Kara , Andrew Morton , Linus Torvalds , Peter Zijlstra , "Rafael J . Wysocki" , Eric Biederman , Greg Kroah-Hartman , Jiri Slaby , Pavel Machek , Len Brown , linux-kernel@vger.kernel.org, lkp@01.org, Sergey Senozhatsky Subject: Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Message-ID: <20170331040438.GA366@jagdpanzerIV.localdomain> References: <20170329092511.3958-9-sergey.senozhatsky@gmail.com> <20170330213829.GA21476@inn.lkp.intel.com> <20170331023506.GB3493@jagdpanzerIV.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170331023506.GB3493@jagdpanzerIV.localdomain> User-Agent: Mutt/1.8.0 (2017-02-23) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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'? does this patch make it any better? --- drivers/tty/sysrq.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c index 817dfb69914d..069f5540be36 100644 --- a/drivers/tty/sysrq.c +++ b/drivers/tty/sysrq.c @@ -240,7 +240,6 @@ static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus); static void sysrq_handle_showallcpus(int key) { - printk_emergency_begin(); /* * Fall back to the workqueue based printing if the * backtrace printing did not succeed or the @@ -255,7 +254,6 @@ static void sysrq_handle_showallcpus(int key) } schedule_work(&sysrq_showallcpus); } - printk_emergency_end(); } static struct sysrq_key_op sysrq_showallcpus_op = { @@ -282,10 +280,8 @@ static struct sysrq_key_op sysrq_showregs_op = { static void sysrq_handle_showstate(int key) { - printk_emergency_begin(); show_state(); show_workqueue_state(); - printk_emergency_end(); } static struct sysrq_key_op sysrq_showstate_op = { .handler = sysrq_handle_showstate, @@ -296,9 +292,7 @@ static struct sysrq_key_op sysrq_showstate_op = { static void sysrq_handle_showstate_blocked(int key) { - printk_emergency_begin(); show_state_filter(TASK_UNINTERRUPTIBLE); - printk_emergency_end(); } static struct sysrq_key_op sysrq_showstate_blocked_op = { .handler = sysrq_handle_showstate_blocked, @@ -537,6 +531,7 @@ void __handle_sysrq(int key, bool check_mask) int orig_log_level; int i; + printk_emergency_begin(); rcu_sysrq_start(); rcu_read_lock(); /* @@ -582,6 +577,7 @@ void __handle_sysrq(int key, bool check_mask) } rcu_read_unlock(); rcu_sysrq_end(); + printk_emergency_end(); } void handle_sysrq(int key) -- 2.12.2