rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 0-....: (1 GPs behind) idle=5c7/1/0x4000000000000000 softirq=173154/173155 fqs=5244 (t=10502 jiffies g=213701 q=1845) NMI backtrace for cpu 0 CPU: 0 PID: 1228 Comm: aoe_tx0 Not tainted 5.16.0-rc6-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:106 nmi_cpu_backtrace.cold+0x47/0x144 lib/nmi_backtrace.c:111 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:343 print_cpu_stall kernel/rcu/tree_stall.h:627 [inline] check_cpu_stall kernel/rcu/tree_stall.h:711 [inline] rcu_pending kernel/rcu/tree.c:3878 [inline] rcu_sched_clock_irq.cold+0x9d/0x746 kernel/rcu/tree.c:2597 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:1428 __run_hrtimer kernel/time/hrtimer.c:1685 [inline] __hrtimer_run_queues+0x1c0/0xe50 kernel/time/hrtimer.c:1749 hrtimer_interrupt+0x31c/0x790 kernel/time/hrtimer.c:1811 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1086 [inline] __sysvec_apic_timer_interrupt+0x146/0x530 arch/x86/kernel/apic/apic.c:1103 sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1097 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 RIP: 0010:arch_atomic_try_cmpxchg arch/x86/include/asm/atomic.h:202 [inline] RIP: 0010:arch_atomic_fetch_add_unless include/linux/atomic/atomic-arch-fallback.h:1163 [inline] RIP: 0010:arch_atomic_add_unless include/linux/atomic/atomic-arch-fallback.h:1183 [inline] RIP: 0010:atomic_add_unless include/linux/atomic/atomic-instrumented.h:571 [inline] RIP: 0010:uart_port_ref drivers/tty/serial/serial_core.c:60 [inline] RIP: 0010:uart_write+0xcb/0x570 drivers/tty/serial/serial_core.c:577 Code: 9d 98 03 00 00 e8 35 58 36 fd 31 ff 89 de e8 4c 5a 36 fd 85 db 0f 84 cc 02 00 00 e8 1f 58 36 fd 8d 53 01 89 d8 f0 41 0f b1 16 <41> 0f 94 c7 31 ff 89 c3 44 89 fe e8 e5 5b 36 fd 45 84 ff 74 c6 e8 RSP: 0018:ffffc9000533faa0 EFLAGS: 00000246 RAX: 0000000000000001 RBX: 0000000000000001 RCX: 0000000000000000 RDX: 0000000000000002 RSI: ffffffff84408071 RDI: 0000000000000003 RBP: ffff8881471c0be8 R08: 0000000000000000 R09: ffff8881471c0f83 R10: ffffffff84408064 R11: 0000000000000000 R12: 0000000000000020 R13: ffff88801599d0b0 R14: ffff8881471c0f80 R15: 0000000000000000 handle_tx+0x204/0x610 drivers/net/caif/caif_serial.c:236 __netdev_start_xmit include/linux/netdevice.h:4994 [inline] netdev_start_xmit include/linux/netdevice.h:5008 [inline] xmit_one net/core/dev.c:3590 [inline] dev_hard_start_xmit+0x1eb/0x920 net/core/dev.c:3606 __dev_queue_xmit+0x299a/0x3650 net/core/dev.c:4229 tx+0x68/0xb0 drivers/block/aoe/aoenet.c:63 kthread+0x1e7/0x3b0 drivers/block/aoe/aoecmd.c:1230 kthread+0x405/0x4f0 kernel/kthread.c:327 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 ---------------- Code disassembly (best guess): 0: 9d popfq 1: 98 cwtl 2: 03 00 add (%rax),%eax 4: 00 e8 add %ch,%al 6: 35 58 36 fd 31 xor $0x31fd3658,%eax b: ff 89 de e8 4c 5a decl 0x5a4ce8de(%rcx) 11: 36 fd ss std 13: 85 db test %ebx,%ebx 15: 0f 84 cc 02 00 00 je 0x2e7 1b: e8 1f 58 36 fd callq 0xfd36583f 20: 8d 53 01 lea 0x1(%rbx),%edx 23: 89 d8 mov %ebx,%eax 25: f0 41 0f b1 16 lock cmpxchg %edx,(%r14) * 2a: 41 0f 94 c7 sete %r15b <-- trapping instruction 2e: 31 ff xor %edi,%edi 30: 89 c3 mov %eax,%ebx 32: 44 89 fe mov %r15d,%esi 35: e8 e5 5b 36 fd callq 0xfd365c1f 3a: 45 84 ff test %r15b,%r15b 3d: 74 c6 je 0x5 3f: e8 .byte 0xe8