FYI, we noticed the following commit: https://github.com/0day-ci/linux Rhyland-Klein/power_supply-power_supply_read_temp-only-if-use_cnt-0/20160604-043353 commit 7f8d22d52dade417e135fd1c08ab9977882ff0b6 ("power_supply: power_supply_read_temp only if use_cnt > 0") on test machine: vm-kbuild-yocto-x86_64: 1 threads qemu-system-x86_64 -enable-kvm -cpu SandyBridge with 320M memory caused below changes: +----------------+------------+------------+ | | 4a99fa06a8 | 7f8d22d52d | +----------------+------------+------------+ | boot_successes | 4 | 0 | +----------------+------------+------------+ [ 2.427327] power_supply test_battery: uevent [ 2.427748] power_supply test_battery: POWER_SUPPLY_NAME=test_battery [ 2.428409] ------------[ cut here ]------------ [ 2.428895] WARNING: CPU: 0 PID: 1 at drivers/power/power_supply_core.c:569 power_supply_read_temp+0x87/0x90 [ 2.430001] CPU: 0 PID: 1 Comm: swapper Not tainted 4.6.0-rc2-00006-g7f8d22d #1 [ 2.430700] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014 [ 2.431570] 0000000000000000 ffff880012857cd0 ffffffff81493375 ffff880012857d10 [ 2.432524] ffffffff81082d09 0000023912857d18 ffff88000e8ad000 ffff880012857d84 [ 2.433723] ffff88000e8adbc0 ffffffff823f6ec0 ffff88000e8ad800 ffff880012857d20 [ 2.434597] Call Trace: [ 2.434843] [] dump_stack+0x19/0x24 [ 2.435341] [] __warn+0xb9/0xe0 [ 2.435799] [] warn_slowpath_null+0x18/0x20 [ 2.436358] [] power_supply_read_temp+0x87/0x90 [ 2.436939] [] thermal_zone_get_temp+0x4f/0x70 [ 2.437519] [] thermal_zone_device_update+0x17/0x110 [ 2.438214] [] ? debug_object_init+0x16/0x20 [ 2.438778] [] thermal_zone_device_register+0x834/0x920 [ 2.439431] [] __power_supply_register+0x242/0x500 [ 2.440041] [] power_supply_register+0xe/0x10 [ 2.440626] [] test_power_init+0x4b/0xb2 [ 2.441160] [] ? wm831x_backup_driver_init+0x14/0x14 [ 2.441799] [] do_one_initcall+0xf1/0x182 [ 2.442344] [] ? set_debug_rodata+0x12/0x12 [ 2.442896] [] kernel_init_freeable+0x11f/0x1a7 [ 2.443488] [] kernel_init+0x9/0xf0 [ 2.443995] [] ret_from_fork+0x22/0x40 [ 2.444522] [] ? rest_init+0x80/0x80 [ 2.445028] ---[ end trace cc5ecf4c9ffecec6 ]--- [ 2.445495] __power_supply_register: Expected proper parent device for 'test_usb' FYI, raw QEMU command line is: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -kernel /pkg/linux/x86_64-randconfig-s2-06040635/gcc-6/7f8d22d52dade417e135fd1c08ab9977882ff0b6/vmlinuz-4.6.0-rc2-00006-g7f8d22d -append 'root=/dev/ram0 user=lkp job=/lkp/scheduled/vm-kbuild-yocto-x86_64-6/bisect_boot-1-yocto-minimal-x86_64.cgz-x86_64-randconfig-s2-06040635-7f8d22d52dade417e135fd1c08ab9977882ff0b6-20160604-100904-1gq6z3z-1.yaml ARCH=x86_64 kconfig=x86_64-randconfig-s2-06040635 branch=linux-devel/devel-spot-201606040556 commit=7f8d22d52dade417e135fd1c08ab9977882ff0b6 BOOT_IMAGE=/pkg/linux/x86_64-randconfig-s2-06040635/gcc-6/7f8d22d52dade417e135fd1c08ab9977882ff0b6/vmlinuz-4.6.0-rc2-00006-g7f8d22d max_uptime=600 RESULT_ROOT=/result/boot/1/vm-kbuild-yocto-x86_64/yocto-minimal-x86_64.cgz/x86_64-randconfig-s2-06040635/gcc-6/7f8d22d52dade417e135fd1c08ab9977882ff0b6/0 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_64-6::dhcp drbd.minor_count=8' -initrd /fs/sdc1/initrd-vm-kbuild-yocto-x86_64-6 -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/sdc1/disk0-vm-kbuild-yocto-x86_64-6,media=disk,if=virtio -pidfile /dev/shm/kboot/pid-vm-kbuild-yocto-x86_64-6 -serial file:/dev/shm/kboot/serial-vm-kbuild-yocto-x86_64-6 -daemonize -display none -monitor null Thanks, Kernel Test Robot