FYI, we noticed the following commit (built with gcc-6):

commit: fae9e65dbd140889bb2a825868cc8a8e01217481 ("[RESEND PATCH v5 2/6] perf/core: Use ioctl to communicate driver configuration to kernel")
url: https://github.com/0day-ci/linux/commits/Mathieu-Poirier/perf-Add-ioctl-for-PMU-driver-configuration/20181218-061024


in testcase: trinity
with following parameters:

	runtime: 300s

test-description: Trinity is a linux system call fuzz tester.
test-url: http://codemonkey.org.uk/projects/trinity/


on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 768M

caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):


+-----------------------------------------------------------------------------------------------+------------+------------+
|                                                                                               | 85f047901c | fae9e65dbd |
+-----------------------------------------------------------------------------------------------+------------+------------+
| boot_successes                                                                                | 16         | 0          |
| boot_failures                                                                                 | 8          | 22         |
| BUG:kernel_hang_in_boot-around-mounting-root_stage                                            | 8          |            |
| BUG:kernel_reboot-without-warning_in_early-boot_stage,last_printk:early_console_in_setup_code | 0          | 22         |
+-----------------------------------------------------------------------------------------------+------------+------------+



early console in setup code
BUG: kernel reboot-without-warning in early-boot stage, last printk: early console in setup code
Linux version 4.20.0-rc7-00038-gfae9e65 #2
Command line: ip=::::vm-snb-quantal-ia32-3::dhcp root=/dev/ram0 user=lkp job=/lkp/jobs/scheduled/vm-snb-quantal-ia32-3/trinity-300s-quantal-core-i386-2018-11-09.cgz-fae9e65dbd140889bb2a825868cc8a8e01217481-20181223-42449-1gtqgwd-3.yaml ARCH=x86_64 kconfig=x86_64-randconfig-s2-12220223 branch=linux-devel/devel-hourly-2018122104 commit=fae9e65dbd140889bb2a825868cc8a8e01217481 BOOT_IMAGE=/pkg/linux/x86_64-randconfig-s2-12220223/gcc-6/fae9e65dbd140889bb2a825868cc8a8e01217481/vmlinuz-4.20.0-rc7-00038-gfae9e65 max_uptime=1500 RESULT_ROOT=/result/trinity/300s/vm-snb-quantal-ia32/quantal-core-i386-2018-11-09.cgz/x86_64-randconfig-s2-12220223/gcc-6/fae9e65dbd140889bb2a825868cc8a8e01217481/3 LKP_SERVER=inn debug apic=debug sysrq_always_enabled rcupdate.rcu_cpu_stall_timeout=100 net.ifnames=0 printk.devkmsg=on panic=-1 softlockup_panic=1 nmi_watchdog=panic oops=panic load_ramdisk=2 prompt_ramdisk=0 drbd.minor_count=8 systemd.log_level=err ignore_loglevel console=tty0 earlyprintk=ttyS0,115200 console=ttyS0,115200 vga=normal rw drbd.minor_count=8 rcuperf.shutdown=0

Elapsed time: 10


To reproduce:

        git clone https://github.com/intel/lkp-tests.git
        cd lkp-tests
        bin/lkp qemu -k <bzImage> job-script # job-script is attached in this email



Thanks,
lkp