FYI, we noticed the following commit (built with gcc-5): commit: 24c764abfd0d4b6e8e33c3818b668edbb4936d6f ("auxdisplay: deconfuse configuration") https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master in testcase: locktorture with following parameters: runtime: 300s test: default test-description: This torture test consists of creating a number of kernel threads which acquire the lock and hold it for specific amount of time, thus simulating different critical region behaviors. test-url: https://www.kernel.org/doc/Documentation/locking/locktorture.txt on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 2G caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): [ 10.294087 ] random: systemd: uninitialized urandom read (16 bytes read) [ 10.298543 ] random: systemd: uninitialized urandom read (16 bytes read) Mounting RPC Pipe File System... Mounting Debug File System... Starting Journal Service... Starting Load Kernel Modules... [ 10.503136 ] random: fast init done Starting Remount Root and Kernel File Systems... Mounting FUSE Control File System... Starting Apply Kernel Variables... Mounting Configuration File System... Starting Create Static Device Nodes in /dev... Starting Load/Save Random Seed... Starting udev Coldplug all Devices... Starting Preprocess NFS configuration... Starting Raise network interfaces... Starting udev Kernel Device Manager... Starting Flush Journal to Persistent Storage... Starting Create Volatile Files and Directories... Starting Network Time Synchronization... Starting RPC bind portmap service... Starting Update UTMP about System Boot/Shutdown... [ 11.126278 ] _warn_unseeded_randomness: 391 callbacks suppressed [ 11.126285 ] random: get_random_u64 called from arch_rnd+0x20/0x37 with crng_init=1 [ 11.127744 ] random: get_random_u64 called from load_elf_binary+0x330/0x13fa with crng_init=1 [ 11.128656 ] random: get_random_u64 called from arch_rnd+0x20/0x37 with crng_init=1 [ 12.271342 ] _warn_unseeded_randomness: 26 callbacks suppressed [ 12.271348 ] random: get_random_u64 called from arch_rnd+0x20/0x37 with crng_init=1 [ 12.272835 ] random: get_random_u64 called from load_elf_binary+0x330/0x13fa with crng_init=1 [ 12.272840 ] random: get_random_u32 called from arch_align_stack+0x28/0x3a with crng_init=1 Starting Permit User Sessions... [ 12.359892 ] parport_pc 00:04: reported by Plug and Play ACPI [ 12.361256 ] parport0: PC-style at 0x378, irq 7 [PCSPP(,...)] Starting LSB: Execute the kexec -e command to reboot system... Starting Login Service... ••••••••• [ 12.488387 ] rtc_cmos 00:00: alarms up to one day, y3k, 114 bytes nvram, hpet irqs Starting System Logging Service... Starting LKP bootstrap... Starting /etc/rc.local Compatibility... Starting OpenBSD Secure Shell server... Starting LSB: Start and stop bmc-watchdog... [ 12.475680 ] rc.local[353]: PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/lkp/lkp/src/bin [ 12.676342 ] parport0: cannot grant exclusive access for device pps_parport [ 12.677670 ] pps_parport: couldn't register with parport0 [ 12.684501 ] parport_pc parport_pc.956: Unable to set coherent dma mask: disabling DMA [ 12.705830 ] parport_pc parport_pc.888: Unable to set coherent dma mask: disabling DMA [ 12.744332 ] parport_pc parport_pc.632: Unable to set coherent dma mask: disabling DMA [ 12.769682 ] Linux agpgart interface v0.103 Starting LSB: Load kernel image with kexec... [ 13.224353 ] PCI Interrupt Link [LNKD] enabled at IRQ 10 [ 13.274820 ] _warn_unseeded_randomness: 338 callbacks suppressed [ 13.274827 ] random: get_random_u64 called from arch_rnd+0x20/0x37 with crng_init=1 [ 13.276289 ] random: get_random_u64 called from load_elf_binary+0x330/0x13fa with crng_init=1 [ 13.278156 ] random: get_random_u64 called from arch_rnd+0x20/0x37 with crng_init=1 [ 13.308315 ] [drm] Found bochs VGA, ID 0xb0c0. [ 13.308798 ] [drm] Framebuffer size 16384 kB @ 0xfd000000, mmio @ 0xfebf0000. [ 13.560302 ] AVX version of gcm_enc/dec engaged. [ 13.560812 ] AES CTR mode by8 optimization enabled To reproduce: # build kernel cd linux cp config-5.0.0-00006-g24c764a .config make HOSTCC=gcc-5 CC=gcc-5 ARCH=x86_64 olddefconfig make HOSTCC=gcc-5 CC=gcc-5 ARCH=x86_64 prepare make HOSTCC=gcc-5 CC=gcc-5 ARCH=x86_64 modules_prepare make HOSTCC=gcc-5 CC=gcc-5 ARCH=x86_64 SHELL=/bin/bash make HOSTCC=gcc-5 CC=gcc-5 ARCH=x86_64 bzImage git clone https://github.com/intel/lkp-tests.git cd lkp-tests find lib/ | cpio -o -H newc --quiet | gzip > modules.cgz bin/lkp qemu -k -m modules.cgz job-script # job-script is attached in this email Thanks, Rong Chen