FYI, we noticed the following commit (built with gcc-5):

commit: c5e4567adde451fa795a93138e2a073e1524c4c6 ("x86/paravirt: Convert natively patched pv ops to use paravirt alternatives")
https://git.kernel.org/cgit/linux/kernel/git/jpoimboe/linux.git paravirt-alternatives

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 -m 420M

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


+-----------------------------------------------+------------+------------+
|                                               | fbf1dda2cf | c5e4567add |
+-----------------------------------------------+------------+------------+
| boot_successes                                | 20         | 0          |
| boot_failures                                 | 0          | 38         |
| kernel_BUG_at_arch/x86/include/asm/paravirt.h | 0          | 38         |
| PANIC:early_exception                         | 0          | 38         |
| EIP:do_page_fault                             | 0          | 38         |
+-----------------------------------------------+------------+------------+



[    0.000000] kernel BUG at arch/x86/include/asm/paravirt.h:57!
PANIC: early exception 0x06 IP 60:410160a2 error 0 cr2 0x0
[    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.14.0-rc2-00013-gc5e4567 #1
[    0.000000] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
[    0.000000] task: 41b41580 task.stack: 41b36000
[    0.000000] EIP: do_page_fault+0x9/0x29
[    0.000000] EFLAGS: 00210046 CPU: 0
[    0.000000] EAX: 41b2e224 EBX: 41b41580 ECX: 0000007b EDX: 00000000
[    0.000000] ESI: 00000000 EDI: 41016099 EBP: 41b2e225 ESP: 41b2e220
[    0.000000]  DS: 007b ES: 007b FS: 0000 GS: 0000 SS: 0068

Elapsed time: 10
Linux version 4.14.0-rc2-00013-gc5e4567 #1
Command line: ip=::::vm-lkp-nhm-dp1-openwrt-ia32-8::dhcp root=/dev/ram0 user=lkp job=/lkp/scheduled/vm-lkp-nhm-dp1-openwrt-ia32-8/trinity-300s-openwrt-i386-2016-03-16.cgz-c5e4567adde451fa795a93138e2a073e1524c4c6-20171008-26079-1m7md6a-0.yaml ARCH=i386 kconfig=i386-randconfig-sb0-10051205 branch=linux-devel/devel-hourly-2017100504 commit=c5e4567adde451fa795a93138e2a073e1524c4c6 BOOT_IMAGE=/pkg/linux/i386-randconfig-sb0-10051205/gcc-5/c5e4567adde451fa795a93138e2a073e1524c4c6/vmlinuz-4.14.0-rc2-00013-gc5e4567 max_uptime=1500 RESULT_ROOT=/result/trinity/300s/vm-lkp-nhm-dp1-openwrt-ia32/openwrt-i386-2016-03-16.cgz/i386-randconfig-sb0-10051205/gcc-5/c5e4567adde451fa795a93138e2a073e1524c4c6/0 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

initrds=(
	/osimage/openwrt/openwrt-i386-2016-03-16.cgz
	/lkp/scheduled/vm-lkp-nhm-dp1-openwrt-ia32-8/trinity-300s-openwrt-i386-2016-03-16.cgz-c5e4567adde451fa795a93138e2a073e1524c4c6-20171008-26079-1m7md6a-0.cgz
	/lkp/lkp/lkp-i386.cgz
	/osimage/pkg/static/trinity-i386.cgz
)

cat "${initrds[@]}" > /fs/sda3/initrd-vm-lkp-nhm-dp1-openwrt-ia32-8

kvm=(
	qemu-system-x86_64
	-enable-kvm
	-kernel /pkg/linux/i386-randconfig-sb0-10051205/gcc-5/c5e4567adde451fa795a93138e2a073e1524c4c6/vmlinuz-4.14.0-rc2-00013-gc5e4567
	-initrd /fs/sda3/initrd-vm-lkp-nhm-dp1-openwrt-ia32-8
	-m 420
	-smp 1
	-device e1000,netdev=net0
	-netdev user,id=net0
	-boot order=nc
	-no-reboot
	-watchdog i6300esb
	-watchdog-action debug
	-rtc base=localtime
	-pidfile /dev/shm/kboot/pid-vm-lkp-nhm-dp1-openwrt-ia32-8
	-serial file:/dev/shm/kboot/vm-lkp-nhm-dp1-openwrt-ia32-8/serial
	-serial file:/dev/shm/kboot/vm-lkp-nhm-dp1-openwrt-ia32-8/kmsg
	-daemonize
	-display none
	-monitor null
)

append=(
	ip=::::vm-lkp-nhm-dp1-openwrt-ia32-8::dhcp
	root=/dev/ram0
	user=lkp
	job=/lkp/scheduled/vm-lkp-nhm-dp1-openwrt-ia32-8/trinity-300s-openwrt-i386-2016-03-16.cgz-c5e4567adde451fa795a93138e2a073e1524c4c6-20171008-26079-1m7md6a-0.yaml
	ARCH=i386
	kconfig=i386-randconfig-sb0-10051205
	branch=linux-devel/devel-hourly-2017100504
	commit=c5e4567adde451fa795a93138e2a073e1524c4c6
	BOOT_IMAGE=/pkg/linux/i386-randconfig-sb0-10051205/gcc-5/c5e4567adde451fa795a93138e2a073e1524c4c6/vmlinuz-4.14.0-rc2-00013-gc5e4567
	max_uptime=1500
	RESULT_ROOT=/result/trinity/300s/vm-lkp-nhm-dp1-openwrt-ia32/openwrt-i386-2016-03-16.cgz/i386-randconfig-sb0-10051205/gcc-5/c5e4567adde451fa795a93138e2a073e1524c4c6/0
	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
)

"${kvm[@]}" -append "${append[*]}"


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,
Xiaolong