FYI, we noticed the following commit: https://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux.git release commit b27ec289fd005833b27d694d9c2dbb716c5cdff7 ("x86 tsc: enumerate SKL cpu_khz and tsc_khz via CPUID") on test machine: vm-kbuild-yocto-x86_64: 1 threads qemu-system-x86_64 -enable-kvm -cpu SandyBridge with 320M memory caused below changes: +-----------------------------------------------------------+------------+------------+ | | a6b5c3ecd3 | b27ec289fd | +-----------------------------------------------------------+------------+------------+ | boot_successes | 8 | 0 | | boot_failures | 2 | 10 | | IP-Config:Auto-configuration_of_network_failed | 2 | 4 | | WARNING:at_arch/x86/mm/extable.c:#ex_handler_rdmsr_unsafe | 0 | 6 | | backtrace:native_calibrate_cpu | 0 | 6 | | backtrace:tsc_init | 0 | 6 | | backtrace:x86_late_time_init | 0 | 6 | +-----------------------------------------------------------+------------+------------+ [ 0.000000] hpet clockevent registered [ 0.000000] ------------[ cut here ]------------ [ 0.000000] ------------[ cut here ]------------ [ 0.000000] WARNING: CPU: 0 PID: 0 at arch/x86/mm/extable.c:50 ex_handler_rdmsr_unsafe+0x48/0x99 [ 0.000000] WARNING: CPU: 0 PID: 0 at arch/x86/mm/extable.c:50 ex_handler_rdmsr_unsafe+0x48/0x99 [ 0.000000] unchecked MSR access error: RDMSR from 0xce [ 0.000000] unchecked MSR access error: RDMSR from 0xce [ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.7.0-rc3-00009-gb27ec28 #1 [ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.7.0-rc3-00009-gb27ec28 #1 [ 0.000000] 0000000000000000 [ 0.000000] 0000000000000000 ffffffff8f207930 ffffffff8f207930 ffffffff8c510068 ffffffff8c510068 ffffffff8f207970 ffffffff8f207970 [ 0.000000] ffffffff8bef8b3d [ 0.000000] ffffffff8bef8b3d 0000003200000009 0000003200000009 fffffbfff1e40f30 fffffbfff1e40f30 ffffffff8f207ac8 ffffffff8f207ac8 [ 0.000000] ffffffff8deb5a80 [ 0.000000] ffffffff8deb5a80 ffffffff8deb5a80 ffffffff8deb5a80 00000000ffffffff 00000000ffffffff ffffffff8f207a20 ffffffff8f207a20 [ 0.000000] Call Trace: [ 0.000000] Call Trace: [ 0.000000] [<ffffffff8c510068>] dump_stack+0x19/0x1b [ 0.000000] [<ffffffff8c510068>] dump_stack+0x19/0x1b [ 0.000000] [<ffffffff8bef8b3d>] __warn+0xee/0x109 [ 0.000000] [<ffffffff8bef8b3d>] __warn+0xee/0x109 [ 0.000000] [<ffffffff8bef8bed>] warn_slowpath_fmt+0x95/0xae [ 0.000000] [<ffffffff8bef8bed>] warn_slowpath_fmt+0x95/0xae [ 0.000000] [<ffffffff8bef8b58>] ? __warn+0x109/0x109 [ 0.000000] [<ffffffff8bef8b58>] ? __warn+0x109/0x109 [ 0.000000] [<ffffffff8de7a0ff>] ? retint_kernel+0x2c/0x2c [ 0.000000] [<ffffffff8de7a0ff>] ? retint_kernel+0x2c/0x2c [ 0.000000] [<ffffffff8be6204d>] ex_handler_rdmsr_unsafe+0x48/0x99 [ 0.000000] [<ffffffff8be6204d>] ex_handler_rdmsr_unsafe+0x48/0x99 [ 0.000000] [<ffffffff8be62005>] ? ex_handler_ext+0x60/0x60 [ 0.000000] [<ffffffff8be62005>] ? ex_handler_ext+0x60/0x60 [ 0.000000] [<ffffffff8be62221>] fixup_exception+0x54/0x60 [ 0.000000] [<ffffffff8be62221>] fixup_exception+0x54/0x60 [ 0.000000] [<ffffffff8be25705>] do_general_protection+0x85/0x20e [ 0.000000] [<ffffffff8be25705>] do_general_protection+0x85/0x20e [ 0.000000] [<ffffffff8de7b098>] general_protection+0x28/0x30 [ 0.000000] [<ffffffff8de7b098>] general_protection+0x28/0x30 [ 0.000000] [<ffffffff8be584af>] ? native_read_msr+0x8/0x38 [ 0.000000] [<ffffffff8be584af>] ? native_read_msr+0x8/0x38 [ 0.000000] [<ffffffff8be2e54f>] ? cpu_khz_from_msr+0xd9/0x1c2 [ 0.000000] [<ffffffff8be2e54f>] ? cpu_khz_from_msr+0xd9/0x1c2 [ 0.000000] [<ffffffff8be2e567>] cpu_khz_from_msr+0xf1/0x1c2 [ 0.000000] [<ffffffff8be2e567>] cpu_khz_from_msr+0xf1/0x1c2 [ 0.000000] [<ffffffff8be2dbf5>] native_calibrate_cpu+0x169/0x762 [ 0.000000] [<ffffffff8be2dbf5>] native_calibrate_cpu+0x169/0x762 [ 0.000000] [<ffffffff8c516955>] ? __radix_tree_lookup+0x10b/0x180 [ 0.000000] [<ffffffff8c516955>] ? __radix_tree_lookup+0x10b/0x180 [ 0.000000] [<ffffffff8c51684a>] ? __radix_tree_insert+0x16f/0x16f [ 0.000000] [<ffffffff8c51684a>] ? __radix_tree_insert+0x16f/0x16f [ 0.000000] [<ffffffff8be2da8c>] ? native_calibrate_tsc+0x1a4/0x1a4 [ 0.000000] [<ffffffff8be2da8c>] ? native_calibrate_tsc+0x1a4/0x1a4 [ 0.000000] [<ffffffff8c51d8a7>] ? format_decode+0x9b/0x387 [ 0.000000] [<ffffffff8c51d8a7>] ? format_decode+0x9b/0x387 [ 0.000000] [<ffffffff8c516a55>] ? radix_tree_lookup+0xd/0xf [ 0.000000] [<ffffffff8c516a55>] ? radix_tree_lookup+0xd/0xf [ 0.000000] [<ffffffff8bf445ec>] ? irq_to_desc+0x17/0x19 [ 0.000000] [<ffffffff8bf445ec>] ? irq_to_desc+0x17/0x19 [ 0.000000] [<ffffffff8bf4d886>] ? register_handler_proc+0x96/0x230 [ 0.000000] [<ffffffff8bf4d886>] ? register_handler_proc+0x96/0x230 [ 0.000000] [<ffffffff8be0201a>] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 0.000000] [<ffffffff8be0201a>] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 0.000000] [<ffffffff8bf4d7f0>] ? irq_spurious_proc_show+0x8e/0x8e [ 0.000000] [<ffffffff8bf4d7f0>] ? irq_spurious_proc_show+0x8e/0x8e [ 0.000000] [<ffffffff8de7a0ff>] ? retint_kernel+0x2c/0x2c [ 0.000000] [<ffffffff8de7a0ff>] ? retint_kernel+0x2c/0x2c [ 0.000000] [<ffffffff8bf4da20>] ? register_handler_proc+0x230/0x230 [ 0.000000] [<ffffffff8bf4da20>] ? register_handler_proc+0x230/0x230 [ 0.000000] [<ffffffff8de791c8>] ? _raw_spin_unlock_irqrestore+0x52/0x84 [ 0.000000] [<ffffffff8de791c8>] ? _raw_spin_unlock_irqrestore+0x52/0x84 [ 0.000000] [<ffffffff8fec1668>] tsc_init+0xac/0x5c6 [ 0.000000] [<ffffffff8fec1668>] tsc_init+0xac/0x5c6 [ 0.000000] [<ffffffff8fec15bc>] ? init_tsc_clocksource+0xe4/0xe4 [ 0.000000] [<ffffffff8fec15bc>] ? init_tsc_clocksource+0xe4/0xe4 [ 0.000000] [<ffffffff8bf46db6>] ? __setup_irq+0x697/0x829 [ 0.000000] [<ffffffff8bf46db6>] ? __setup_irq+0x697/0x829 [ 0.000000] [<ffffffff8bf470ab>] ? setup_irq+0xa1/0xbe [ 0.000000] [<ffffffff8bf470ab>] ? setup_irq+0xa1/0xbe [ 0.000000] [<ffffffff8febb906>] x86_late_time_init+0x1b/0x1d [ 0.000000] [<ffffffff8febb906>] x86_late_time_init+0x1b/0x1d [ 0.000000] [<ffffffff8febb906>] ? x86_late_time_init+0x1b/0x1d [ 0.000000] [<ffffffff8febb906>] ? x86_late_time_init+0x1b/0x1d [ 0.000000] [<ffffffff8feb12dd>] start_kernel+0x499/0x535 [ 0.000000] [<ffffffff8feb12dd>] start_kernel+0x499/0x535 [ 0.000000] [<ffffffff8feb0e44>] ? thread_info_cache_init+0x6/0x6 [ 0.000000] [<ffffffff8feb0e44>] ? thread_info_cache_init+0x6/0x6 [ 0.000000] [<ffffffff8de71bb3>] ? memblock_reserve+0x4a/0x4f [ 0.000000] [<ffffffff8de71bb3>] ? memblock_reserve+0x4a/0x4f [ 0.000000] [<ffffffff8feb0120>] ? early_idt_handler_array+0x120/0x120 [ 0.000000] [<ffffffff8feb0120>] ? early_idt_handler_array+0x120/0x120 [ 0.000000] [<ffffffff8feb0120>] ? early_idt_handler_array+0x120/0x120 [ 0.000000] [<ffffffff8feb0120>] ? early_idt_handler_array+0x120/0x120 [ 0.000000] [<ffffffff8feb02ae>] x86_64_start_reservations+0x2f/0x31 [ 0.000000] [<ffffffff8feb02ae>] x86_64_start_reservations+0x2f/0x31 [ 0.000000] [<ffffffff8feb042e>] x86_64_start_kernel+0x17e/0x18d [ 0.000000] [<ffffffff8feb042e>] x86_64_start_kernel+0x17e/0x18d [ 0.000000] ---[ end trace d97b395864960a98 ]--- [ 0.000000] ---[ end trace d97b395864960a98 ]--- FYI, raw QEMU command line is: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -kernel /pkg/linux/x86_64-randconfig-s1-06180836/gcc-6/b27ec289fd005833b27d694d9c2dbb716c5cdff7/vmlinuz-4.7.0-rc3-00009-gb27ec28 -append 'root=/dev/ram0 user=lkp job=/lkp/scheduled/vm-kbuild-yocto-x86_64-29/bisect_boot-1-yocto-minimal-x86_64.cgz-x86_64-randconfig-s1-06180836-b27ec289fd005833b27d694d9c2dbb716c5cdff7-20160619-33752-1s8x56t-0.yaml~ ARCH=x86_64 kconfig=x86_64-randconfig-s1-06180836 branch=linux-devel/devel-hourly-2016061804 commit=b27ec289fd005833b27d694d9c2dbb716c5cdff7 BOOT_IMAGE=/pkg/linux/x86_64-randconfig-s1-06180836/gcc-6/b27ec289fd005833b27d694d9c2dbb716c5cdff7/vmlinuz-4.7.0-rc3-00009-gb27ec28 max_uptime=600 RESULT_ROOT=/result/boot/1/vm-kbuild-yocto-x86_64/yocto-minimal-x86_64.cgz/x86_64-randconfig-s1-06180836/gcc-6/b27ec289fd005833b27d694d9c2dbb716c5cdff7/0 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-kbuild-yocto-x86_64-29::dhcp drbd.minor_count=8' -initrd /fs/sde1/initrd-vm-kbuild-yocto-x86_64-29 -m 320 -smp 1 -device e1000,netdev=net0 -netdev user,id=net0 -boot order=nc -no-reboot -watchdog i6300esb -rtc base=localtime -drive file=/fs/sde1/disk0-vm-kbuild-yocto-x86_64-29,media=disk,if=virtio -pidfile /dev/shm/kboot/pid-vm-kbuild-yocto-x86_64-29 -serial file:/dev/shm/kboot/serial-vm-kbuild-yocto-x86_64-29 -daemonize -display none -monitor null Thanks, Kernel Test Robot