From: Feng Tang <feng.tang@intel.com>
To: Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org
Cc: Feng Tang <feng.tang@intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Kees Cook <keescook@chromium.org>, Borislav Petkov <bp@suse.de>,
stable@kernel.org
Subject: [PATCH v3] panic: Avoid the extra noise dmesg
Date: Tue, 4 Dec 2018 13:43:48 +0800 [thread overview]
Message-ID: <1543902228-23834-1-git-send-email-feng.tang@intel.com> (raw)
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
For people working in console mode, the screen will first show the panic
call stack, but immediately overridded by these noisy extra messages, which
makes debugging much more difficult, as the original context gets lost on
screen.
Also these noisy messages will confuse some users, as I have seen many bug
reporters posted the noisy message into bugzilla, instead of the real panic
call stack and context.
Removing the "local_irq_enable" will avoid the noisy message.
The justification for the removing is: when code runs to this point, it
means user has chosed to not reboot, or do any special handling by using
the panic notifier method, no much point in re-enabling the interrupt.
Signed-off-by: Feng Tang <feng.tang@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: stable@kernel.org
---
kernel/panic.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/kernel/panic.c b/kernel/panic.c
index f6d549a..a616e55 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -295,7 +295,6 @@ void panic(const char *fmt, ...)
}
#endif
pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf);
- local_irq_enable();
for (i = 0; ; i += PANIC_TIMER_STEP) {
touch_softlockup_watchdog();
if (i >= i_next) {
--
2.7.4
next reply other threads:[~2018-12-04 5:42 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-04 5:43 Feng Tang [this message]
2018-12-04 16:13 ` [PATCH v3] panic: Avoid the extra noise dmesg Kees Cook
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1543902228-23834-1-git-send-email-feng.tang@intel.com \
--to=feng.tang@intel.com \
--cc=akpm@linux-foundation.org \
--cc=bp@suse.de \
--cc=keescook@chromium.org \
--cc=linux-kernel@vger.kernel.org \
--cc=stable@kernel.org \
--cc=tglx@linutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).