rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 0-....: (1 GPs behind) idle=6e6/1/0x4000000000000000 softirq=40466/40467 fqs=1300 (t=10501 jiffies g=65477 q=34729) NMI backtrace for cpu 0 CPU: 0 PID: 8884 Comm: syz-executor.4 Not tainted 5.14.0-rc7-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105 nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0x25e/0x3f0 kernel/rcu/tree_stall.h:342 print_cpu_stall kernel/rcu/tree_stall.h:625 [inline] check_cpu_stall kernel/rcu/tree_stall.h:700 [inline] rcu_pending kernel/rcu/tree.c:3922 [inline] rcu_sched_clock_irq.cold+0x9f/0x747 kernel/rcu/tree.c:2641 update_process_times+0x16d/0x200 kernel/time/timer.c:1785 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:226 tick_sched_timer+0x1b0/0x2d0 kernel/time/tick-sched.c:1421 __run_hrtimer kernel/time/hrtimer.c:1537 [inline] __hrtimer_run_queues+0x1c0/0xe50 kernel/time/hrtimer.c:1601 hrtimer_interrupt+0x330/0xa00 kernel/time/hrtimer.c:1663 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1089 [inline] __sysvec_apic_timer_interrupt+0x146/0x530 arch/x86/kernel/apic/apic.c:1106 sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1100 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0x38/0x70 kernel/locking/spinlock.c:191 Code: 74 24 10 e8 5a fa 2d f8 48 89 ef e8 02 70 2e f8 81 e3 00 02 00 00 75 25 9c 58 f6 c4 02 75 2d 48 85 db 74 01 fb bf 01 00 00 00 c3 4d 22 f8 65 8b 05 bc c8 d4 76 85 c0 74 0a 5b 5d c3 e8 a0 aa RSP: 0000:ffffc900016bfa50 EFLAGS: 00000206 RAX: 0000000000000006 RBX: 0000000000000200 RCX: 1ffffffff1fa7b3a RDX: 0000000000000000 RSI: 0000000000000101 RDI: 0000000000000001 RBP: ffff88802102c000 R08: 0000000000000001 R09: ffffffff8fcd59f7 R10: 0000000000000001 R11: ffffc90010094000 R12: ffff8880ad4d5b08 R13: ffff888016ac2000 R14: dffffc0000000000 R15: ffff8880ad4d5b00 spin_unlock_irqrestore include/linux/spinlock.h:409 [inline] dummy_timer+0x12f6/0x32b0 drivers/usb/gadget/udc/dummy_hcd.c:2001 call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421 expire_timers kernel/time/timer.c:1466 [inline] __run_timers.part.0+0x675/0xa20 kernel/time/timer.c:1734 __run_timers kernel/time/timer.c:1715 [inline] run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1747 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558 invoke_softirq kernel/softirq.c:432 [inline] __irq_exit_rcu+0x16e/0x1c0 kernel/softirq.c:636 irq_exit_rcu+0x5/0x20 kernel/softirq.c:648 sysvec_apic_timer_interrupt+0x45/0xc0 arch/x86/kernel/apic/apic.c:1100 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 RIP: 0033:0x48a7c1 Code: 24 0c 89 3c 24 48 89 4c 24 18 e8 aa e7 ff ff 4c 8b 54 24 18 48 8b 54 24 10 41 89 c0 8b 74 24 0c 8b 3c 24 b8 e6 00 00 00 0f 05 <44> 89 c7 48 89 04 24 e8 e3 e7 ff ff 48 8b 04 24 eb 97 66 2e 0f 1f RSP: 002b:0000000000a9fd00 EFLAGS: 00000293 RAX: 0000000000000000 RBX: 0000000000000497 RCX: 000000000048a7c1 RDX: 0000000000a9fd40 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000a9fddc R08: 0000000000000000 R09: 00007fff43694080 R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000032 R13: 00000000000707f9 R14: 0000000000000002 R15: 0000000000a9fe40 ---------------- Code disassembly (best guess): 0: 74 24 je 0x26 2: 10 e8 adc %ch,%al 4: 5a pop %rdx 5: fa cli 6: 2d f8 48 89 ef sub $0xef8948f8,%eax b: e8 02 70 2e f8 callq 0xf82e7012 10: 81 e3 00 02 00 00 and $0x200,%ebx 16: 75 25 jne 0x3d 18: 9c pushfq 19: 58 pop %rax 1a: f6 c4 02 test $0x2,%ah 1d: 75 2d jne 0x4c 1f: 48 85 db test %rbx,%rbx 22: 74 01 je 0x25 24: fb sti 25: bf 01 00 00 00 mov $0x1,%edi * 2a: e8 c3 4d 22 f8 callq 0xf8224df2 <-- trapping instruction 2f: 65 8b 05 bc c8 d4 76 mov %gs:0x76d4c8bc(%rip),%eax # 0x76d4c8f2 36: 85 c0 test %eax,%eax 38: 74 0a je 0x44 3a: 5b pop %rbx 3b: 5d pop %rbp 3c: c3 retq 3d: e8 .byte 0xe8 3e: a0 .byte 0xa0 3f: aa stos %al,%es:(%rdi)