rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 1-...!: (1 GPs behind) idle=74a/1/0x4000000000000002 softirq=10522/10523 fqs=37 (t=10500 jiffies g=6113 q=98) rcu: rcu_preempt kthread starved for 10424 jiffies! g6113 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29032 10 2 0x80004000 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x9a0/0xcc0 kernel/sched/core.c:4081 schedule+0x181/0x210 kernel/sched/core.c:4155 schedule_timeout+0x14f/0x240 kernel/time/timer.c:1895 rcu_gp_fqs_loop kernel/rcu/tree.c:1661 [inline] rcu_gp_kthread+0xed8/0x1770 kernel/rcu/tree.c:1821 kthread+0x332/0x350 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 NMI backtrace for cpu 1 CPU: 1 PID: 8198 Comm: syz-executor.1 Not tainted 5.4.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1fb/0x318 lib/dump_stack.c:118 nmi_cpu_backtrace+0xaf/0x1a0 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x174/0x290 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x10/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0x15a/0x220 kernel/rcu/tree_stall.h:254 print_cpu_stall kernel/rcu/tree_stall.h:455 [inline] check_cpu_stall kernel/rcu/tree_stall.h:529 [inline] rcu_pending kernel/rcu/tree.c:2827 [inline] rcu_sched_clock_irq+0xe25/0x1ad0 kernel/rcu/tree.c:2271 update_process_times+0x12d/0x180 kernel/time/timer.c:1726 tick_sched_handle kernel/time/tick-sched.c:167 [inline] tick_sched_timer+0x263/0x420 kernel/time/tick-sched.c:1310 __run_hrtimer kernel/time/hrtimer.c:1514 [inline] __hrtimer_run_queues+0x403/0x840 kernel/time/hrtimer.c:1576 hrtimer_interrupt+0x38c/0xda0 kernel/time/hrtimer.c:1638 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline] smp_apic_timer_interrupt+0x109/0x280 arch/x86/kernel/apic/apic.c:1135 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 RIP: 0010:__sanitizer_cov_trace_pc+0x27/0x50 kernel/kcov.c:105 Code: 5d c3 cc 48 8b 04 24 65 48 8b 0c 25 c0 1d 02 00 65 8b 15 b8 81 8b 7e f7 c2 00 01 1f 00 75 2c 8b 91 80 13 00 00 83 fa 02 75 21 <48> 8b 91 88 13 00 00 48 8b 32 48 8d 7e 01 8b 89 84 13 00 00 48 39 RSP: 0018:ffffc900025d7400 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: ffffffff81486ea4 RBX: ffffea00025377c0 RCX: ffff88806c140040 RDX: 0000000000000002 RSI: 000000000003ffff RDI: 0000000000040000 RBP: ffffc900025d7440 R08: dffffc0000000000 R09: fffffbfff120248a R10: fffffbfff120248a R11: 0000000000000000 R12: ffff888092832d20 R13: dffffc0000000000 R14: 1ffff110125065a4 R15: ffff8880a7e7b7e8 release_task_stack kernel/fork.c:440 [inline] put_task_stack+0xa3/0x130 kernel/fork.c:451 finish_task_switch+0x3f1/0x550 kernel/sched/core.c:3256 context_switch kernel/sched/core.c:3388 [inline] __schedule+0x9a8/0xcc0 kernel/sched/core.c:4081 preempt_schedule_irq+0xc1/0x140 kernel/sched/core.c:4338 retint_kernel+0x1b/0x2b RIP: 0010:empty_bucket net/ipv4/tcp_ipv4.c:2197 [inline] RIP: 0010:established_get_first+0x181/0x410 net/ipv4/tcp_ipv4.c:2218 Code: 03 48 b9 00 00 00 00 00 fc ff df 80 3c 08 00 74 08 48 89 df e8 40 10 f2 fa 48 8b 1b 48 89 de 48 83 e6 01 31 ff e8 5f 9d b6 fa <48> 83 e3 01 0f 85 65 01 00 00 45 21 ee 49 6b c6 38 49 01 c4 4c 89 RSP: 0018:ffffc900025d7658 EFLAGS: 00000297 ORIG_RAX: ffffffffffffff02 RAX: 0000000000000002 RBX: 000000000000719b RCX: dffffc0000000000 RDX: ffff88806c140040 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc900025d76b0 R08: ffffffff86c002d1 R09: fffffbfff13c8d2d R10: fffffbfff13c8d2d R11: 0000000000000000 R12: ffff8880a5659c00 R13: 00000000000038cd R14: 0000000000000003 R15: ffff8880960d3798 established_get_idx net/ipv4/tcp_ipv4.c:2266 [inline] tcp_get_idx+0x181/0x2a0 net/ipv4/tcp_ipv4.c:2285 tcp_seq_next+0xb6/0x220 net/ipv4/tcp_ipv4.c:2353 seq_read+0x952/0xd70 fs/seq_file.c:258 proc_reg_read+0x1e2/0x2d0 fs/proc/inode.c:223 do_loop_readv_writev fs/read_write.c:714 [inline] do_iter_read+0x4b1/0x5b0 fs/read_write.c:935 vfs_readv+0xc2/0x120 fs/read_write.c:997 kernel_readv fs/splice.c:365 [inline] default_file_splice_read+0x559/0xa10 fs/splice.c:422 do_splice_to fs/splice.c:890 [inline] splice_direct_to_actor+0x3e2/0xb90 fs/splice.c:969 do_splice_direct+0x200/0x330 fs/splice.c:1078 do_sendfile+0x7e4/0xfd0 fs/read_write.c:1464 __do_sys_sendfile64 fs/read_write.c:1525 [inline] __se_sys_sendfile64 fs/read_write.c:1511 [inline] __x64_sys_sendfile64+0x176/0x1b0 fs/read_write.c:1511 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45a679 Code: ad 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 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f36e1cdbc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000045a679 RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000004 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 000000007ffff000 R11: 0000000000000246 R12: 00007f36e1cdc6d4 R13: 00000000004c8f16 R14: 00000000004e0a30 R15: 00000000ffffffff