FYI, we noticed the following commit (built with gcc-7): commit: b7d48fb89aa672ee3acaac2864a3bfda81606ef1 ("sched: Add task_struct pointer to sched_class::set_curr_task") https://kernel.googlesource.com/pub/scm/linux/kernel/git/peterz/queue.git sched/core in testcase: rcutorture with following parameters: runtime: 300s test: cpuhotplug torture_type: srcud 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): +------------------------------------------------------+------------+------------+ | | 0f922d0d29 | b7d48fb89a | +------------------------------------------------------+------------+------------+ | boot_successes | 0 | 0 | | boot_failures | 8 | 8 | | BUG:kernel_reboot-without-warning_in_test_stage | 8 | | | WARNING:at_kernel/sched/sched.h:#pick_next_task_fair | 0 | 8 | | RIP:pick_next_task_fair | 0 | 8 | | WARNING:at_kernel/sched/sched.h:#sched_cpu_dying | 0 | 8 | | RIP:sched_cpu_dying | 0 | 8 | +------------------------------------------------------+------------+------------+ If you fix the issue, kindly add following tag Reported-by: kernel test robot <rong.a.chen(a)intel.com&gt; [ 38.967800] WARNING: CPU: 1 PID: 15 at kernel/sched/sched.h:1754 pick_next_task_fair+0x758/0x780 [ 38.971162] Modules linked in: rcutorture torture intel_rapl_msr intel_rapl_common crct10dif_pclmul crc32_pclmul crc32c_intel bochs_drm ghash_clmulni_intel drm_vram_helper ppdev ttm snd_pcm snd_timer snd drm_kms_helper soundcore pcspkr drm joydev serio_raw parport_pc floppy parport qemu_fw_cfg ata_generic i2c_piix4 pata_acpi [ 38.978871] CPU: 1 PID: 15 Comm: migration/1 Not tainted 5.3.0-rc1-00087-gb7d48fb89aa672 #1 [ 38.980246] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 [ 38.981631] RIP: 0010:pick_next_task_fair+0x758/0x780 [ 38.982468] Code: 48 0f af 85 18 01 00 00 48 83 c1 01 48 f7 f1 48 89 83 10 0a 00 00 e9 66 fa ff ff bf 02 00 00 00 e8 8d 3a ff ff e9 04 fa ff ff <0f> 0b e9 19 fb ff ff 80 3d 65 5e 61 01 00 0f 85 30 fc ff ff e8 bf [ 38.985513] RSP: 0000:ffffb98c8008bcf8 EFLAGS: 00010002 [ 38.986376] RAX: ffffffffa2011e00 RBX: ffff8b7ffbb2b3c0 RCX: ffffffffa264d540 [ 38.987544] RDX: ffffb98c8008bd80 RSI: 0000000000000001 RDI: ffff8b7ffbb2b3c0 [ 38.988728] RBP: ffffb98c8008bdc0 R08: 0000000912a90774 R09: 0000000000000004 [ 38.989913] R10: ffffb98c8008bd38 R11: 0000000000000003 R12: ffff8b7ffbb2b3c0 [ 38.991079] R13: ffffffffa264d540 R14: ffffb98c8008bd80 R15: 0000000000000000 [ 38.992251] FS: 0000000000000000(0000) GS:ffff8b7ffbb00000(0000) knlGS:0000000000000000 [ 38.993579] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 38.994522] CR2: 000000005788d734 CR3: 000000007e104000 CR4: 00000000000406e0 [ 38.995689] Call Trace: [ 38.996124] ? sched_cpu_starting+0xf0/0xf0 [ 38.996823] sched_cpu_dying+0x2a9/0x430 [ 38.997484] ? sched_cpu_starting+0xf0/0xf0 [ 38.998231] cpuhp_invoke_callback+0x86/0x5d0 [ 38.998957] ? cpu_disable_common+0x217/0x230 [ 38.999684] take_cpu_down+0x60/0xb0 [ 39.000283] multi_cpu_stop+0x6b/0x100 [ 39.000909] ? stop_machine_yield+0x10/0x10 [ 39.001612] cpu_stopper_thread+0x94/0x100 [ 39.002293] ? smpboot_thread_fn+0x2f/0x1e0 [ 39.002988] ? smpboot_thread_fn+0x74/0x1e0 [ 39.003683] ? smpboot_thread_fn+0x14e/0x1e0 [ 39.004393] smpboot_thread_fn+0x149/0x1e0 [ 39.005073] ? sort_range+0x20/0x20 [ 39.005662] kthread+0x11e/0x140 [ 39.006203] ? kthread_park+0xa0/0xa0 [ 39.006814] ret_from_fork+0x35/0x40 [ 39.007411] ---[ end trace baf171d5e73cc4a2 ]--- To reproduce: # build kernel cd linux cp config-5.3.0-rc1-00087-gb7d48fb89aa672 .config make HOSTCC=gcc-7 CC=gcc-7 ARCH=x86_64 olddefconfig prepare modules_prepare 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