FYI, we noticed the following commit:

https://github.com/0day-ci/linux Paolo-Bonzini/x86-kvm-use-kvmclock-to-compute-TSC-deadline-value/20160706-013826
commit 0ef38569aa3ebd09e0233c9d34a71d666478eafe ("x86, kvm: use kvmclock to compute TSC deadline value")

in testcase: boot

on test machine: 2 threads qemu-system-x86_64 -enable-kvm -cpu Haswell,+smep,+smap with 360M memory

caused below changes:


+------------------------------------------------------------------+------------+------------+
|                                                                  | 1b74dde7c4 | 0ef38569aa |
+------------------------------------------------------------------+------------+------------+
| boot_successes                                                   | 8          | 2          |
| boot_failures                                                    | 0          | 12         |
| WARNING:at_kernel/time/clockevents.c:#clockevents_switch_state() | 0          | 12         |
| RIP:arch_local_irq_enable                                        | 0          | 4          |
| Kernel_panic-not_syncing:softlockup:hung_tasks                   | 0          | 4          |
| backtrace:native_smp_prepare_cpus                                | 0          | 12         |
| backtrace:kernel_init_freeable                                   | 0          | 12         |
| backtrace:cpu_startup_entry                                      | 0          | 3          |
| backtrace:vfs_writev                                             | 0          | 1          |
| backtrace:SyS_writev                                             | 0          | 1          |
+------------------------------------------------------------------+------------+------------+



[    5.763520] ..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1
[    5.772441] TSC deadline timer enabled
[    5.785628] ------------[ cut here ]------------
[    5.803804] WARNING: CPU: 0 PID: 1 at kernel/time/clockevents.c:169 clockevents_switch_state+0xe2/0xe7()
[    5.807759] Modules linked in:
[    5.808914] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.5.0-rc2-00003-g0ef3856 #1
[    5.817803] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014
[    5.833446]  0000000000000000 ffff880032963d20 ffffffff81762032 0000000000000000
[    5.845736]  ffff880032963d58 ffffffff810de181 ffffffff8114999b ffff88003460d8c0
[    5.849386]  0000000000000003 ffffffff84008288 0000000000000000 ffff880032963d68
[    5.852248] Call Trace:
[    5.853094]  [<ffffffff81762032>] dump_stack+0x4b/0x63
[    5.855622]  [<ffffffff810de181>] warn_slowpath_common+0x99/0xb2
[    5.865993]  [<ffffffff8114999b>] ? clockevents_switch_state+0xe2/0xe7
[    5.877079]  [<ffffffff810de24d>] warn_slowpath_null+0x1a/0x1c
[    5.887160]  [<ffffffff8114999b>] clockevents_switch_state+0xe2/0xe7
[    5.897985]  [<ffffffff8114a361>] tick_setup_periodic+0xdd/0x102
[    5.908321]  [<ffffffff8114a07d>] ? tick_periodic+0xac/0xac
[    5.916472]  [<ffffffff8114a441>] tick_setup_device+0xbb/0xd8
[    5.919136]  [<ffffffff8114a5be>] tick_check_new_device+0xb4/0xd2
[    5.921421]  [<ffffffff811496ef>] clockevents_register_device+0xb0/0x10a
[    5.923539]  [<ffffffff8108abbf>] setup_APIC_timer+0x85/0x88
[    5.926847]  [<ffffffff8463304f>] setup_boot_APIC_clock+0x4b4/0x4c3
[    5.939872]  [<ffffffff8108ff0c>] ? native_apic_msr_read+0x1f/0x25
[    5.954592]  [<ffffffff8463347f>] apic_bsp_setup+0x94/0x99
[    5.961707]  [<ffffffff84631390>] native_smp_prepare_cpus+0x238/0x2b1
[    5.965000]  [<ffffffff8461a072>] kernel_init_freeable+0xfd/0x24e
[    5.967597]  [<ffffffff82ea6859>] ? rest_init+0x140/0x140
[    5.976939]  [<ffffffff82ea6867>] kernel_init+0xe/0xde
[    5.989976]  [<ffffffff82eb2edf>] ret_from_fork+0x3f/0x70
[    6.003575]  [<ffffffff82ea6859>] ? rest_init+0x140/0x140
[    6.007376] ---[ end trace dae74bcedd07403f ]---
[    6.901932] smpboot: CPU0: Intel Core Processor (Haswell) (family: 0x6, model: 0x3c, stepping: 0x1)


FYI, raw QEMU command line is:

	qemu-system-x86_64 -enable-kvm -cpu Haswell,+smep,+smap -kernel /pkg/linux/x86_64-allyesdebian/gcc-6/0ef38569aa3ebd09e0233c9d34a71d666478eafe/vmlinuz-4.5.0-rc2-00003-g0ef3856 -append 'root=/dev/ram0 user=lkp job=/lkp/scheduled/vm-lkp-wsx03-quantal-x86_64-6/rand_boot-1-quantal-core-x86_64.cgz-x86_64-allyesdebian-0ef38569aa3ebd09e0233c9d34a71d666478eafe-20160706-124362-1gcvh1x-0.yaml ARCH=x86_64 kconfig=x86_64-allyesdebian branch=linux-devel/devel-catchup-201607060215 commit=0ef38569aa3ebd09e0233c9d34a71d666478eafe BOOT_IMAGE=/pkg/linux/x86_64-allyesdebian/gcc-6/0ef38569aa3ebd09e0233c9d34a71d666478eafe/vmlinuz-4.5.0-rc2-00003-g0ef3856 max_uptime=600 RESULT_ROOT=/result/boot/1/vm-lkp-wsx03-quantal-x86_64/quantal-core-x86_64.cgz/x86_64-allyesdebian/gcc-6/0ef38569aa3ebd09e0233c9d34a71d666478eafe/0 LKP_SERVER=inn earlyprintk=ttyS0,115200 systemd.log_level=err debug apic=debug sysrq_always_enabled rcupdate.rcu_cpu_stall_timeout=100 panic=-1 softlockup_panic=1 nmi_watchdog=panic oops=panic load_ramdisk=2 prompt_ramdisk=0 console=ttyS0,115200 console=tty0 vga=normal rw ip=::::vm-lkp-wsx03-quantal-x86_64-6::dhcp drbd.minor_count=8'  -initrd /fs/sdc1/initrd-vm-lkp-wsx03-quantal-x86_64-6 -m 872 -smp 2 -device e1000,netdev=net0 -netdev user,id=net0 -boot order=nc -no-reboot -watchdog i6300esb -rtc base=localtime -pidfile /dev/shm/kboot/pid-vm-lkp-wsx03-quantal-x86_64-6 -serial file:/dev/shm/kboot/serial-vm-lkp-wsx03-quantal-x86_64-6 -daemonize -display none -monitor null 





Thanks,
Kernel Test Robot