bisecting fixing commit since c636eef2ee3696f261a35f34989842701a107895 building syzkaller on bb3e5fe608aa1d99df8f41cee2dcc33fdef06123 testing commit c636eef2ee3696f261a35f34989842701a107895 with gcc (GCC) 8.1.0 kernel signature: 72960483226801fb68b814ee5e015ddf29dd2ace33dcf8af5448787e660b3629 run #0: crashed: INFO: rcu detected stall in do_idle run #1: crashed: INFO: rcu detected stall in sys_clock_settime run #2: crashed: INFO: rcu detected stall in do_idle run #3: crashed: INFO: rcu detected stall in smp_call_function run #4: crashed: INFO: rcu detected stall in sys_clock_settime run #5: crashed: INFO: rcu detected stall in sys_clock_settime run #6: crashed: INFO: rcu detected stall in sys_clock_settime run #7: crashed: INFO: rcu detected stall in sys_clock_settime run #8: crashed: INFO: rcu detected stall in sys_clock_settime run #9: crashed: INFO: rcu detected stall in linkwatch_event testing current HEAD f5e6c330254ae691f6d7befe61c786eb5056007e testing commit f5e6c330254ae691f6d7befe61c786eb5056007e with gcc (GCC) 8.1.0 kernel signature: f4ffebbd959139681dbfba5a8e50f1406c7568180ecc4fd39236851d280579ff run #0: crashed: INFO: rcu detected stall in smp_call_function run #1: crashed: INFO: rcu detected stall in smp_call_function run #2: crashed: INFO: rcu detected stall in smp_call_function run #3: crashed: BUG: soft lockup in smp_call_function run #4: crashed: BUG: soft lockup in smp_call_function run #5: crashed: BUG: soft lockup in smp_call_function run #6: crashed: BUG: soft lockup in smp_call_function run #7: crashed: INFO: rcu detected stall in sys_clock_settime run #8: crashed: INFO: rcu detected stall in sys_clock_settime run #9: crashed: INFO: rcu detected stall in sys_clock_settime revisions tested: 2, total time: 21m1.004652615s (build: 9m36.978804333s, test: 10m43.802934142s) the crash still happens on HEAD commit msg: Merge tag 'spi-fix-v5.11-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi crash: INFO: rcu detected stall in sys_clock_settime rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 1-...!: (1 GPs behind) idle=dca/1/0x4000000000000000 softirq=9022/9026 fqs=0 (t=19022 jiffies g=3457 q=811) rcu: rcu_preempt kthread starved for 19022 jiffies! g3457 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior. rcu: RCU grace-period kthread stack dump: task:rcu_preempt state:I stack:14648 pid: 12 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4313 [inline] __schedule+0x420/0x900 kernel/sched/core.c:5064 schedule+0x38/0xe0 kernel/sched/core.c:5143 schedule_timeout+0x1be/0x2e0 kernel/time/timer.c:1878 rcu_gp_fqs_loop kernel/rcu/tree.c:1940 [inline] rcu_gp_kthread+0x758/0xcc0 kernel/rcu/tree.c:2113 kthread+0x145/0x170 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 NMI backtrace for cpu 1 CPU: 1 PID: 7458 Comm: syz-executor.2 Not tainted 5.11.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0xa3/0xc8 lib/dump_stack.c:120 nmi_cpu_backtrace.cold.8+0x53/0x6d lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0xd5/0xf0 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0xa2/0xce kernel/rcu/tree_stall.h:337 print_cpu_stall kernel/rcu/tree_stall.h:569 [inline] check_cpu_stall kernel/rcu/tree_stall.h:643 [inline] rcu_pending kernel/rcu/tree.c:3751 [inline] rcu_sched_clock_irq.cold.97+0x61/0x5eb kernel/rcu/tree.c:2580 update_process_times+0x8e/0xc0 kernel/time/timer.c:1782 tick_sched_handle.isra.21+0x1a/0x50 kernel/time/tick-sched.c:226 tick_sched_timer+0x6a/0x80 kernel/time/tick-sched.c:1369 __run_hrtimer kernel/time/hrtimer.c:1519 [inline] __hrtimer_run_queues+0x1e3/0x4f0 kernel/time/hrtimer.c:1583 hrtimer_interrupt+0xf9/0x210 kernel/time/hrtimer.c:1645 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1085 [inline] __sysvec_apic_timer_interrupt+0x8e/0x290 arch/x86/kernel/apic/apic.c:1102 asm_call_irq_on_stack+0xf/0x20 __run_sysvec_on_irqstack arch/x86/include/asm/irq_stack.h:37 [inline] run_sysvec_on_irqstack_cond arch/x86/include/asm/irq_stack.h:89 [inline] sysvec_apic_timer_interrupt+0xcc/0xf0 arch/x86/kernel/apic/apic.c:1096 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:628 RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:653 [inline] RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0x32/0x70 kernel/locking/spinlock.c:191 Code: 53 48 89 f3 48 8b 74 24 10 e8 3a cf 10 fe 48 89 ef e8 d2 12 11 fe f6 c7 02 75 2c 48 83 3d ad f2 39 01 00 74 31 48 89 df 57 9d <0f> 1f 44 00 00 bf 01 00 00 00 e8 0f 55 0d fe 65 8b 05 08 96 ee 7c RSP: 0018:ffffc9000025fe70 EFLAGS: 00000286 RAX: 000000000000001b RBX: 0000000000000286 RCX: ffffc9000025fe34 RDX: 0000000000000000 RSI: ffffffff83f40fb3 RDI: 0000000000000286 RBP: ffff8881164af688 R08: 0000000000000001 R09: 0000000000000001 R10: 000000000053ccf7 R11: 000000000000a400 R12: 0000000000000286 R13: 1bc16d5cbd7aaeed R14: 7fffffffffffffff R15: ffff8881164af688 spin_unlock_irqrestore include/linux/spinlock.h:409 [inline] timerfd_clock_was_set+0xc8/0x180 fs/timerfd.c:113 do_settimeofday64+0x179/0x210 kernel/time/timekeeping.c:1327 __do_sys_clock_settime kernel/time/posix-timers.c:1079 [inline] __se_sys_clock_settime kernel/time/posix-timers.c:1067 [inline] __x64_sys_clock_settime+0x64/0xb0 kernel/time/posix-timers.c:1067 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45ce69 Code: 2d b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 fb b5 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fb54b91ac78 EFLAGS: 00000246 ORIG_RAX: 00000000000000e3 RAX: ffffffffffffffda RBX: 0000000000001f00 RCX: 000000000045ce69 RDX: 0000000000000000 RSI: 0000000020000400 RDI: 0000000000000000 RBP: 000000000118c098 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118c06c R13: 00007ffd6835177f R14: 00007fb54b91b9c0 R15: 000000000118c06c