FYI, we noticed the following commit: https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git sched/rt commit 5c19b8321d53e04f697008ec5de862bf583da646 ("sched/rtmutex: Refactor rt_mutex_setprio()") on test machine: vm-kbuild-yocto-x86_64: 1 threads qemu-system-x86_64 -enable-kvm -cpu SandyBridge with 320M memory caused below changes: +-----------------------------------------------------------+------------+------------+ | | 053205581a | 5c19b8321d | +-----------------------------------------------------------+------------+------------+ | boot_successes | 73 | 5 | | boot_failures | 40 | 26 | | BUG:kernel_test_crashed | 11 | 1 | | Mem-Info | 2 | | | Out_of_memory:Kill_process | 2 | | | backtrace:__vmalloc | 2 | | | backtrace:SYSC_init_module | 2 | | | backtrace:SyS_init_module | 2 | | | Kernel_panic-not_syncing:Attempted_to_kill_init!exitcode= | 27 | 5 | | BUG:unable_to_handle_kernel | 0 | 20 | | Oops | 0 | 20 | | RIP:rt_mutex_adjust_prio | 0 | 20 | | Kernel_panic-not_syncing:Fatal_exception | 0 | 20 | | backtrace:rt_mutex_lock | 0 | 20 | +-----------------------------------------------------------+------------+------------+ [ 5.908894] Duration of test: 773542794 ns [ 5.910036] Average test time: 780690536 [ 5.910665] Testing concurrent rhashtable access from 10 threads [ 12.633256] BUG: unable to handle kernel NULL pointer dereference at 0000000000000018 [ 12.637603] IP: [<ffffffff8110058e>] rt_mutex_adjust_prio+0x7e/0xb0 [ 12.638792] PGD 0 [ 12.639222] Oops: 0000 [#1] PREEMPT [ 12.639866] Modules linked in: [ 12.640473] CPU: 0 PID: 11 Comm: rcub/0 Not tainted 4.7.0-rc2-00012-g5c19b83 #1 [ 12.641764] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014 [ 12.643331] task: ffff8800120ca400 ti: ffff8800120d0000 task.ti: ffff8800120d0000 [ 12.644594] RIP: 0010:[<ffffffff8110058e>] [<ffffffff8110058e>] rt_mutex_adjust_prio+0x7e/0xb0 [ 12.646105] RSP: 0000:ffff8800120d3cd8 EFLAGS: 00010046 [ 12.647001] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000001 [ 12.648080] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff81edee78 [ 12.649155] RBP: ffff8800120d3cf0 R08: ffffffff827aca30 R09: 0000000000000243 [ 12.650431] R10: 0000000000000001 R11: ffffffff827aca30 R12: ffff8800120ca400 [ 12.651697] R13: 0000000000000001 R14: ffff88000f23c800 R15: ffff8800120caa78 [ 12.652966] FS: 0000000000000000(0000) GS:ffffffff81e31000(0000) knlGS:0000000000000000 [ 12.654205] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 12.655010] CR2: 0000000000000018 CR3: 0000000001e0c000 CR4: 00000000000406f0 [ 12.656026] Stack: [ 12.656406] ffffffff81e484e0 ffff8800120d3d68 ffff8800120ca400 ffff8800120d3d48 [ 12.657804] ffffffff81100e5a ffffffff811017d9 ffffffff81e484e0 0000000000000286 [ 12.659051] 0000000000000000 ffffffff81e484e0 ffff8800120ca400 0000000000000000 [ 12.660510] Call Trace: [ 12.660987] [<ffffffff81100e5a>] task_blocks_on_rt_mutex+0x4a/0x1e0 [ 12.662156] [<ffffffff811017d9>] ? do_raw_spin_lock+0xe9/0x170 [ 12.663209] [<ffffffff81892ae9>] rt_mutex_slowlock+0xf9/0x230 [ 12.664253] [<ffffffff8118944b>] ? ftrace_likely_update+0x1bb/0x1d0 [ 12.665391] [<ffffffff810e278c>] ? __might_sleep+0x6c/0xf0 [ 12.666427] [<ffffffff81117eda>] ? rcu_boost_kthread+0x20a/0x7d0 [ 12.667428] [<ffffffff81892c88>] rt_mutex_lock+0x68/0x70 [ 12.668338] [<ffffffff8111809b>] rcu_boost_kthread+0x3cb/0x7d0 [ 12.669204] [<ffffffff81117cd0>] ? cond_synchronize_sched+0x20/0x20 [ 12.670115] [<ffffffff810dab1a>] kthread+0x12a/0x140 [ 12.671020] [<ffffffff8138c268>] ? check_preemption_disabled+0xf8/0x110 [ 12.672206] [<ffffffff818955ef>] ret_from_fork+0x1f/0x40 [ 12.673168] [<ffffffff810da9f0>] ? kthread_create_on_node+0x280/0x280 [ 12.674250] Code: f9 ff fa ff 31 d2 89 de 48 c7 c7 78 ee ed 81 e8 19 8d 08 00 49 8b 84 24 b8 06 00 00 31 f6 48 85 c0 75 0c 49 8b 84 24 c0 06 00 00 <48> 8b 70 18 4c 89 e7 e8 26 60 fe ff 5b 41 5c 41 5d 5d c3 31 d2 [ 12.678661] RIP [<ffffffff8110058e>] rt_mutex_adjust_prio+0x7e/0xb0 [ 12.679814] RSP <ffff8800120d3cd8> [ 12.680459] CR2: 0000000000000018 [ 12.681069] ---[ end trace 12b64a8067a47d21 ]--- [ 12.681895] Kernel panic - not syncing: Fatal exception FYI, raw QEMU command line is: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -kernel /pkg/linux/x86_64-randconfig-s2-06072005/gcc-6/5c19b8321d53e04f697008ec5de862bf583da646/vmlinuz-4.7.0-rc2-00012-g5c19b83 -append 'root=/dev/ram0 user=lkp job=/lkp/scheduled/vm-kbuild-yocto-x86_64-43/bisect_boot-1-yocto-minimal-x86_64.cgz-x86_64-randconfig-s2-06072005-5c19b8321d53e04f697008ec5de862bf583da646-20160608-8029-1ij1fxu-0.yaml~ ARCH=x86_64 kconfig=x86_64-randconfig-s2-06072005 branch=linux-devel/devel-spot-201606072037 commit=5c19b8321d53e04f697008ec5de862bf583da646 BOOT_IMAGE=/pkg/linux/x86_64-randconfig-s2-06072005/gcc-6/5c19b8321d53e04f697008ec5de862bf583da646/vmlinuz-4.7.0-rc2-00012-g5c19b83 max_uptime=600 RESULT_ROOT=/result/boot/1/vm-kbuild-yocto-x86_64/yocto-minimal-x86_64.cgz/x86_64-randconfig-s2-06072005/gcc-6/5c19b8321d53e04f697008ec5de862bf583da646/0 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_64-43::dhcp drbd.minor_count=8' -initrd /fs/sde1/initrd-vm-kbuild-yocto-x86_64-43 -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_64-43,media=disk,if=virtio -pidfile /dev/shm/kboot/pid-vm-kbuild-yocto-x86_64-43 -serial file:/dev/shm/kboot/serial-vm-kbuild-yocto-x86_64-43 -daemonize -display none -monitor null Thanks, Xiaolong