FYI, we noticed the following commit (built with gcc-7): commit: ba26c41d985d7c66c6198e0e22cd287434d83a3e ("rcutorture: Fix stutter_wait() return value and freelist checks") https://git.kernel.org/cgit/linux/kernel/git/paulmck/linux-rcu.git dev.2019.04.28a in testcase: rcutorture with following parameters: runtime: 300s test: default torture_type: srcu test-description: rcutorture is rcutorture kernel module load/unload test. test-url: https://www.kernel.org/doc/Documentation/RCU/torture.txt on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 4G caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): +--------------------------------------------------------------------+------------+------------+ | | fe661764bc | ba26c41d98 | +--------------------------------------------------------------------+------------+------------+ | boot_successes | 314 | 278 | | boot_failures | 18 | 38 | | BUG:kernel_reboot-without-warning_in_test_stage | 5 | 12 | | WARNING:at_net/sched/sch_generic.c:#dev_watchdog | 13 | 12 | | RIP:dev_watchdog | 13 | 12 | | RIP:ring_buffer_lock_reserve | 1 | | | WARNING:at_kernel/rcu/rcutorture.c:#rcu_torture_writer[rcutorture] | 0 | 14 | | RIP:rcu_torture_writer[rcutorture] | 0 | 14 | | calltrace:irq_exit | 0 | 8 | | calltrace:rcu_torture_free | 0 | 1 | | RIP:__rb_reserve_next | 0 | 1 | | RIP:lock_release | 0 | 1 | +--------------------------------------------------------------------+------------+------------+ If you fix the issue, kindly add following tag Reported-by: kernel test robot <rong.a.chen(a)intel.com&gt; [ 348.855994] WARNING: CPU: 1 PID: 605 at kernel/rcu/rcutorture.c:1019 rcu_torture_writer+0x5e5/0x820 [rcutorture] [ 348.858990] Modules linked in: rcutorture(-) torture ppdev parport_pc crct10dif_pclmul crc32c_intel parport rtc_cmos qemu_fw_cfg [ 348.862052] CPU: 1 PID: 605 Comm: rcu_torture_wri Not tainted 5.1.0-rc1-00106-gba26c41 #1 [ 348.864209] RIP: 0010:rcu_torture_writer+0x5e5/0x820 [rcutorture] [ 348.866629] Code: 08 a0 49 8b 06 49 39 c6 75 22 48 8b 55 00 49 8d 46 e8 48 39 c2 74 15 41 8b 56 f8 4c 89 ee 48 c7 c7 d1 83 05 a0 e8 cb 11 0c e1 <0f> 0b 49 83 c6 30 4c 39 f3 75 cd e8 9b 68 ff ff 84 c0 0f 84 97 fc [ 348.871198] RSP: 0018:ffff8881185c3eb8 EFLAGS: 00010296 [ 348.872442] RAX: 0000000000000027 RBX: ffffffffa0085f78 RCX: 0000000000000006 [ 348.874957] RDX: 0000000000000007 RSI: 0000000000000006 RDI: ffff88813bbd1880 [ 348.876675] RBP: ffffffffa0085f68 R08: 0000005dd95e1368 R09: 0000000000000000 [ 348.878449] R10: 0000000000000000 R11: 0000000000000000 R12: ffffffffa005a670 [ 348.880333] R13: ffffffffa0058800 R14: ffffffffa0084dd8 R15: ffffffffa0085750 [ 348.882924] FS: 0000000000000000(0000) GS:ffff88813ba00000(0000) knlGS:0000000000000000 [ 348.885859] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 348.887797] CR2: 00007f89476dc030 CR3: 000000011d91e000 CR4: 00000000000406a0 [ 348.889811] Call Trace: [ 348.890529] ? rcu_torture_pipe_update+0x100/0x100 [rcutorture] [ 348.892393] kthread+0x11c/0x130 [ 348.893012] ? kthread_stop+0x210/0x210 [ 348.893792] ret_from_fork+0x24/0x30 [ 348.894627] irq event stamp: 570574 [ 348.895346] hardirqs last enabled at (570573): [<ffffffff8117d893>] console_unlock+0x533/0x5c0 [ 348.897770] hardirqs last disabled at (570574): [<ffffffff81003417>] trace_hardirqs_off_thunk+0x1a/0x1c [ 348.900200] softirqs last enabled at (570562): [<ffffffff81c00414>] __do_softirq+0x414/0x450 [ 348.902187] softirqs last disabled at (570549): [<ffffffff8111d557>] irq_exit+0x67/0xd0 [ 348.904076] ---[ end trace 497e668e1ed2342a ]--- To reproduce: # build kernel cd linux cp config-5.1.0-rc1-00106-gba26c41 .config make HOSTCC=gcc-7 CC=gcc-7 ARCH=x86_64 olddefconfig make HOSTCC=gcc-7 CC=gcc-7 ARCH=x86_64 prepare make HOSTCC=gcc-7 CC=gcc-7 ARCH=x86_64 modules_prepare make HOSTCC=gcc-7 CC=gcc-7 ARCH=x86_64 SHELL=/bin/bash make HOSTCC=gcc-7 CC=gcc-7 ARCH=x86_64 bzImage git clone https://github.com/intel/lkp-tests.git cd lkp-tests bin/lkp qemu -k <bzImage> job-script # job-script is attached in this email Thanks, Rong Chen