Greeting, FYI, we noticed the following commit (built with gcc-9): commit: d5bff968ea9cc005e632d9369c26cbd8148c93d5 ("workqueue: break affinity initiatively") https://git.kernel.org/cgit/linux/kernel/git/paulmck/linux-rcu.git dev.2021.01.11b in testcase: rcutorture version: 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-i386 -enable-kvm -cpu SandyBridge -smp 2 -m 8G caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): +--------------------------------------------------+------------+------------+ | | 6211b34f6e | d5bff968ea | +--------------------------------------------------+------------+------------+ | boot_successes | 4 | 0 | | boot_failures | 0 | 12 | | WARNING:at_kernel/workqueue.c:#process_one_work | 0 | 12 | | EIP:process_one_work | 0 | 12 | | WARNING:at_kernel/kthread.c:#kthread_set_per_cpu | 0 | 4 | | EIP:kthread_set_per_cpu | 0 | 4 | +--------------------------------------------------+------------+------------+ If you fix the issue, kindly add following tag Reported-by: kernel test robot [ 73.794288] WARNING: CPU: 0 PID: 22 at kernel/workqueue.c:2192 process_one_work (kbuild/src/consumer/kernel/workqueue.c:2192) [ 73.795012] Modules linked in: rcutorture torture mousedev evbug input_leds led_class psmouse pcspkr tiny_power_button button [ 73.795949] CPU: 0 PID: 22 Comm: kworker/1:0 Not tainted 5.11.0-rc3-gd5bff968ea9c #2 [ 73.796592] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 [ 73.797280] Workqueue: 0x0 (rcu_gp) [ 73.797592] EIP: process_one_work (kbuild/src/consumer/kernel/workqueue.c:2192) [ 73.797980] Code: 37 64 a1 58 54 4c 43 39 45 24 74 2c 31 c9 ba 01 00 00 00 c7 04 24 01 00 00 00 b8 08 1d f5 42 e8 94 85 13 00 ff 05 b8 30 04 43 <0f> 0b ba 01 00 00 00 eb 22 8d 74 26 00 90 c7 04 24 01 00 00 00 31 All code ======== 0: 37 (bad) 1: 64 a1 58 54 4c 43 39 movabs %fs:0x74244539434c5458,%eax 8: 45 24 74 b: 2c 31 sub $0x31,%al d: c9 leaveq e: ba 01 00 00 00 mov $0x1,%edx 13: c7 04 24 01 00 00 00 movl $0x1,(%rsp) 1a: b8 08 1d f5 42 mov $0x42f51d08,%eax 1f: e8 94 85 13 00 callq 0x1385b8 24: ff 05 b8 30 04 43 incl 0x430430b8(%rip) # 0x430430e2 2a:* 0f 0b ud2 <-- trapping instruction 2c: ba 01 00 00 00 mov $0x1,%edx 31: eb 22 jmp 0x55 33: 8d 74 26 00 lea 0x0(%rsi,%riz,1),%esi 37: 90 nop 38: c7 04 24 01 00 00 00 movl $0x1,(%rsp) 3f: 31 .byte 0x31 Code starting with the faulting instruction =========================================== 0: 0f 0b ud2 2: ba 01 00 00 00 mov $0x1,%edx 7: eb 22 jmp 0x2b 9: 8d 74 26 00 lea 0x0(%rsi,%riz,1),%esi d: 90 nop e: c7 04 24 01 00 00 00 movl $0x1,(%rsp) 15: 31 .byte 0x31 [ 73.799597] EAX: 42f51d08 EBX: 00000000 ECX: 00000000 EDX: 00000001 [ 73.800143] ESI: 43c04720 EDI: df4140f4 EBP: de7f23c0 ESP: 43d7bf08 [ 73.800688] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 EFLAGS: 00010002 [ 73.801260] CR0: 80050033 CR2: 00aabcbc CR3: 7f9dc000 CR4: 000406d0 [ 73.801784] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000 [ 73.802305] DR6: fffe0ff0 DR7: 00000400 [ 73.802651] Call Trace: [ 73.802871] ? process_one_work (kbuild/src/consumer/kernel/workqueue.c:615 kbuild/src/consumer/kernel/workqueue.c:643 kbuild/src/consumer/kernel/workqueue.c:2248) [ 73.803232] ? worker_thread (kbuild/src/consumer/include/linux/list.h:282 (discriminator 1) kbuild/src/consumer/kernel/workqueue.c:2424 (discriminator 1)) [ 73.803567] ? kthread (kbuild/src/consumer/kernel/kthread.c:292 (discriminator 1)) [ 73.803859] ? create_worker (kbuild/src/consumer/kernel/workqueue.c:2366) [ 73.804192] ? kzalloc (kbuild/src/consumer/kernel/resource.c:166) [ 73.804554] ? ret_from_fork (kbuild/src/consumer/arch/x86/entry/entry_32.S:856) [ 73.804875] ---[ end trace 122a61cfdd814ce9 ]--- [ 73.805580] kvm-guest: stealtime: cpu 1, msr 9e7e6ec0 [ 73.883292] smpboot: CPU 1 is now offline [ 73.951310] x86: Booting SMP configuration: [ 73.951830] smpboot: Booting Node 0 Processor 1 APIC 0x1 [ 73.952546] kvm-clock: cpu 1, msr 34f6021, secondary cpu clock [ 73.952580] masked ExtINT on CPU#1 [ 73.989426] kvm-guest: stealtime: cpu 1, msr 9e7e6ec0 [ 74.164842] smpboot: CPU 1 is now offline [ 74.231330] x86: Booting SMP configuration: [ 74.231866] smpboot: Booting Node 0 Processor 1 APIC 0x1 [ 74.232581] kvm-clock: cpu 1, msr 34f6021, secondary cpu clock [ 74.232617] masked ExtINT on CPU#1 [ 74.262076] kvm-guest: stealtime: cpu 1, msr 9e7e6ec0 [ 74.433467] smpboot: CPU 1 is now offline [ 74.591312] x86: Booting SMP configuration: [ 74.591816] smpboot: Booting Node 0 Processor 1 APIC 0x1 [ 74.592510] kvm-clock: cpu 1, msr 34f6021, secondary cpu clock [ 74.592546] masked ExtINT on CPU#1 [ 74.641675] kvm-guest: stealtime: cpu 1, msr 9e7e6ec0 [ 74.803293] smpboot: CPU 1 is now offline [ 74.841947] x86: Booting SMP configuration: [ 74.842481] smpboot: Booting Node 0 Processor 1 APIC 0x1 [ 74.843206] kvm-clock: cpu 1, msr 34f6021, secondary cpu clock [ 74.843243] masked ExtINT on CPU#1 [ 74.891673] kvm-guest: stealtime: cpu 1, msr 9e7e6ec0 [ 74.973277] smpboot: CPU 1 is now offline [ 75.121309] x86: Booting SMP configuration: [ 75.121836] smpboot: Booting Node 0 Processor 1 APIC 0x1 [ 75.122539] kvm-clock: cpu 1, msr 34f6021, secondary cpu clock [ 75.122573] masked ExtINT on CPU#1 [ 75.171673] kvm-guest: stealtime: cpu 1, msr 9e7e6ec0 [ 75.303292] smpboot: CPU 1 is now offline [ 75.341537] x86: Booting SMP configuration: [ 75.342087] smpboot: Booting Node 0 Processor 1 APIC 0x1 [ 75.342822] kvm-clock: cpu 1, msr 34f6021, secondary cpu clock [ 75.342859] masked ExtINT on CPU#1 [ 75.401637] kvm-guest: stealtime: cpu 1, msr 9e7e6ec0 [ 75.523225] smpboot: CPU 1 is now offline [ 75.631293] x86: Booting SMP configuration: [ 75.631790] smpboot: Booting Node 0 Processor 1 APIC 0x1 [ 75.632512] kvm-clock: cpu 1, msr 34f6021, secondary cpu clock [ 75.632544] masked ExtINT on CPU#1 [ 75.681631] kvm-guest: stealtime: cpu 1, msr 9e7e6ec0 [ 75.813300] smpboot: CPU 1 is now offline [ 75.861498] x86: Booting SMP configuration: [ 75.862040] smpboot: Booting Node 0 Processor 1 APIC 0x1 [ 75.862763] kvm-clock: cpu 1, msr 34f6021, secondary cpu clock [ 75.862797] masked ExtINT on CPU#1 [ 75.911656] kvm-guest: stealtime: cpu 1, msr 9e7e6ec0 [ 76.043254] smpboot: CPU 1 is now offline [ 76.091495] x86: Booting SMP configuration: [ 76.092038] smpboot: Booting Node 0 Processor 1 APIC 0x1 [ 76.092726] kvm-clock: cpu 1, msr 34f6021, secondary cpu clock [ 76.092758] masked ExtINT on CPU#1 [ 76.141672] kvm-guest: stealtime: cpu 1, msr 9e7e6ec0 [ 76.273386] smpboot: CPU 1 is now offline [ 76.321583] x86: Booting SMP configuration: [ 76.322137] smpboot: Booting Node 0 Processor 1 APIC 0x1 [ 76.323186] kvm-clock: cpu 1, msr 34f6021, secondary cpu clock [ 76.323221] masked ExtINT on CPU#1 [ 76.361613] kvm-guest: stealtime: cpu 1, msr 9e7e6ec0 [ 76.453350] smpboot: CPU 1 is now offline [ 76.681296] x86: Booting SMP configuration: [ 76.681792] smpboot: Booting Node 0 Processor 1 APIC 0x1 [ 76.682448] kvm-clock: cpu 1, msr 34f6021, secondary cpu clock [ 76.682479] masked ExtINT on CPU#1 [ 76.731666] kvm-guest: stealtime: cpu 1, msr 9e7e6ec0 [ 76.883233] smpboot: CPU 1 is now offline [ 77.191301] x86: Booting SMP configuration: [ 77.191829] smpboot: Booting Node 0 Processor 1 APIC 0x1 [ 77.192554] kvm-clock: cpu 1, msr 34f6021, secondary cpu clock [ 77.192589] masked ExtINT on CPU#1 [ 77.241673] kvm-guest: stealtime: cpu 1, msr 9e7e6ec0 [ 77.323278] smpboot: CPU 1 is now offline [ 77.361452] x86: Booting SMP configuration: [ 77.361957] smpboot: Booting Node 0 Processor 1 APIC 0x1 [ 77.362632] kvm-clock: cpu 1, msr 34f6021, secondary cpu clock [ 77.362668] masked ExtINT on CPU#1 [ 77.411641] kvm-guest: stealtime: cpu 1, msr 9e7e6ec0 [ 77.583568] smpboot: CPU 1 is now offline [ 77.691303] x86: Booting SMP configuration: [ 77.691851] smpboot: Booting Node 0 Processor 1 APIC 0x1 [ 77.692549] kvm-clock: cpu 1, msr 34f6021, secondary cpu clock [ 77.692581] masked ExtINT on CPU#1 [ 77.751809] kvm-guest: stealtime: cpu 1, msr 9e7e6ec0 [ 78.032676] srcud-torture: rtc: (ptrval) ver: 922 tfle: 0 rta: 922 rtaf: 0 rtf: 913 rtmbe: 0 rtmbkf: 0/0 rtbe: 0 rtbke: 0 rtbre: 0 rtbf: 0 rtb: 0 nt: 552 onoff: 93/93:93/94 2,21:0,21 667:787 (HZ=100) barrier: 0/0:0 read-exits: 67 nocb-toggles: 0:0 [ 78.035048] srcud-torture: Reader Pipe: 12631032 44 0 0 0 0 0 0 0 0 0 [ 78.035759] srcud-torture: Reader Batch: 12630957 119 0 0 0 0 0 0 0 0 0 [ 78.036507] srcud-torture: Free-Block Circulation: 921 921 920 919 918 917 916 915 914 913 0 [ 78.037407] rcu: srcud-torture: Tree SRCU g6668 per-CPU(idx=1): 0(17,12 .) 1(-17,-12 .) T(0,0) [ 78.055649] smpboot: CPU 1 is now offline [ 78.121332] x86: Booting SMP configuration: [ 78.121837] smpboot: Booting Node 0 Processor 1 APIC 0x1 [ 78.150644] kvm-clock: cpu 1, msr 34f6021, secondary cpu clock [ 78.150702] masked ExtINT on CPU#1 [ 78.172354] kvm-guest: stealtime: cpu 1, msr 9e7e6ec0 [ 78.343316] smpboot: CPU 1 is now offline [ 78.411398] x86: Booting SMP configuration: [ 78.411921] smpboot: Booting Node 0 Processor 1 APIC 0x1 [ 78.412640] kvm-clock: cpu 1, msr 34f6021, secondary cpu clock [ 78.412675] masked ExtINT on CPU#1 [ 78.437957] kvm-guest: stealtime: cpu 1, msr 9e7e6ec0 To reproduce: # build kernel cd linux cp config-5.11.0-rc3-gd5bff968ea9c .config make HOSTCC=gcc-9 CC=gcc-9 ARCH=i386 olddefconfig prepare modules_prepare bzImage git clone https://github.com/intel/lkp-tests.git cd lkp-tests bin/lkp qemu -k job-script # job-script is attached in this email Thanks, Oliver Sang