FYI, we noticed the following commit (built with gcc-7): commit: 440391bb72aa95c102e3d9ef006ce1e313a89117 ("[PATCH v3] clocksource: Warn if too many missing ticks are detected") url: https://github.com/0day-ci/linux/commits/Waiman-Long/clocksource-Warn-if-too-many-missing-ticks-are-detected/20180925-150152 in testcase: autotest with following parameters: test: pi_tests test-description: Autotest is a framework for fully automated testing. It is designed primarily to test the Linux kernel, though it is useful for many other functions such as qualifying new hardware. test-url: https://github.com/autotest/autotest on test machine: qemu-system-x86_64 -enable-kvm -cpu qemu64,+ssse3 -smp 4 -m 8G caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): +------------------------------------------------------------+------------+------------+ | | 9ac669fc01 | 440391bb72 | +------------------------------------------------------------+------------+------------+ | boot_successes | 56 | 14 | | boot_failures | 1 | 4 | | BUG:kernel_hang_in_test_stage | 1 | | | WARNING:at_kernel/time/clocksource.c:#clocksource_watchdog | 0 | 4 | | RIP:clocksource_watchdog | 0 | 4 | +------------------------------------------------------------+------------+------------+ [ 315.330209] WARNING: CPU: 3 PID: 27 at kernel/time/clocksource.c:218 clocksource_watchdog+0x353/0x360 [ 315.333092] Modules linked in: sd_mod sg ata_generic pata_acpi ppdev snd_pcm virtio_scsi snd_timer snd soundcore pcspkr ata_piix serio_raw i2c_piix4 libata parport_pc parport floppy ip_tables [ 315.337348] CPU: 3 PID: 27 Comm: ksoftirqd/3 Not tainted 4.19.0-rc1-00018-g440391b #1 [ 315.339492] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 [ 315.341746] RIP: 0010:clocksource_watchdog+0x353/0x360 [ 315.343127] Code: 89 f9 4c 89 ea 48 c7 c7 40 6c 2d 82 e8 a4 d5 fd ff 48 89 df e8 5e fc ff ff e9 41 fd ff ff 48 c7 c7 40 6b 2d 82 e8 8b d5 fd ff <0f> 0b e9 fb fc ff ff 66 0f 1f 44 00 00 0f 1f 44 00 00 41 57 41 56 [ 315.347738] RSP: 0018:ffffc90000d3fd78 EFLAGS: 00010286 [ 315.349133] RAX: 000000000000002e RBX: 0000000000000100 RCX: 0000000000000000 [ 315.350939] RDX: 0000000000000000 RSI: ffff88023fd96898 RDI: ffff88023fd96898 [ 315.352728] RBP: ffff88023fd9ab00 R08: 0000000000000000 R09: 000000000000002e [ 315.354523] R10: ffffc90000d3fdf0 R11: ffffffff82f86fcd R12: ffffffff83098b40 [ 315.356317] R13: ffffffff811168e0 R14: ffffc90000d3fde0 R15: ffffffff810b578e [ 315.358114] FS: 0000000000000000(0000) GS:ffff88023fd80000(0000) knlGS:0000000000000000 [ 315.360301] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 315.361804] CR2: 00007f8a4ce35670 CR3: 000000000260a000 CR4: 00000000000006e0 [ 315.363605] Call Trace: [ 315.364430] ? __switch_to_asm+0x40/0x70 [ 315.365563] ? __clocksource_unstable+0x60/0x60 [ 315.366831] ? smpboot_thread_fn+0x14e/0x1e0 [ 315.368030] call_timer_fn+0x2b/0x140 [ 315.369102] run_timer_softirq+0x427/0x480 [ 315.370290] ? vfree_atomic+0x33/0x60 [ 315.371407] ? put_task_stack+0x75/0xf0 [ 315.372561] ? finish_task_switch+0x207/0x2a0 [ 315.373826] ? smpboot_thread_fn+0x14e/0x1e0 [ 315.375074] __do_softirq+0xe3/0x2d9 [ 315.376175] ? smpboot_thread_fn+0x2f/0x1e0 [ 315.377400] ? smpboot_thread_fn+0x74/0x1e0 [ 315.378636] ? smpboot_thread_fn+0x14e/0x1e0 [ 315.379880] run_ksoftirqd+0x26/0x50 [ 315.380973] smpboot_thread_fn+0x149/0x1e0 [ 315.382181] ? sort_range+0x20/0x20 [ 315.383259] kthread+0x11e/0x140 [ 315.384282] ? kthread_associate_blkcg+0xb0/0xb0 [ 315.385602] ret_from_fork+0x35/0x40 [ 315.386700] ---[ end trace fcc27924f4248295 ]--- To reproduce: git clone https://github.com/intel/lkp-tests.git cd lkp-tests bin/lkp qemu -k job-script # job-script is attached in this email Thanks, lkp