rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 1-...!: (10501 ticks this GP) idle=7a6/1/0x4000000000000004 softirq=115887/115887 fqs=0 (t=10502 jiffies g=168885 q=1124) rcu: rcu_preempt kthread starved for 10503 jiffies! g168885 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1 rcu: RCU grace-period kthread stack dump: rcu_preempt I29112 10 2 0x80004000 Call Trace: context_switch kernel/sched/core.c:3254 [inline] __schedule+0x755/0x1580 kernel/sched/core.c:3880 schedule+0xd9/0x260 kernel/sched/core.c:3947 schedule_timeout+0x486/0xc50 kernel/time/timer.c:1807 rcu_gp_fqs_loop kernel/rcu/tree.c:1611 [inline] rcu_gp_kthread+0x9b2/0x18c0 kernel/rcu/tree.c:1768 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 NMI backtrace for cpu 1 CPU: 1 PID: 10880 Comm: syz-executor.4 Not tainted 5.3.0-rc8+ #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+0x172/0x1f0 lib/dump_stack.c:113 nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x23b/0x28b lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0x183/0x1cf 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:2736 [inline] rcu_sched_clock_irq.cold+0x4dd/0xc13 kernel/rcu/tree.c:2183 update_process_times+0x32/0x80 kernel/time/timer.c:1639 tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:167 tick_sched_timer+0x53/0x140 kernel/time/tick-sched.c:1296 __run_hrtimer kernel/time/hrtimer.c:1389 [inline] __hrtimer_run_queues+0x364/0xe40 kernel/time/hrtimer.c:1451 hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1509 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1106 [inline] smp_apic_timer_interrupt+0x160/0x610 arch/x86/kernel/apic/apic.c:1131 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830 RIP: 0010:__sanitizer_cov_trace_pc+0x4b/0x50 kernel/kcov.c:112 Code: 90 f0 12 00 00 83 fa 02 75 20 48 8b 88 f8 12 00 00 8b 80 f4 12 00 00 48 8b 11 48 83 c2 01 48 39 d0 76 07 48 89 34 d1 48 89 11 <5d> c3 0f 1f 00 65 4c 8b 04 25 40 fe 01 00 65 8b 05 b8 88 8f 7e a9 RSP: 0018:ffff8880ae908e88 EFLAGS: 00000206 ORIG_RAX: ffffffffffffff13 RAX: ffff888059cd8700 RBX: ffff88809350fdf8 RCX: ffffffff85c660f9 RDX: 0000000000000100 RSI: ffffffff85c65ad1 RDI: ffff88809350fe00 RBP: ffff8880ae908e88 R08: ffff888059cd8700 R09: 0000000000000000 R10: fffffbfff134afaf R11: ffff888059cd8700 R12: dffffc0000000000 R13: ffff88809350fb00 R14: ffff88809350fe98 R15: ffff88809350fe90 __read_once_size include/linux/compiler.h:199 [inline] list_empty include/linux/list.h:268 [inline] hhf_dequeue+0x51/0xa20 net/sched/sch_hhf.c:427 dequeue_skb net/sched/sch_generic.c:258 [inline] qdisc_restart net/sched/sch_generic.c:361 [inline] __qdisc_run+0x1e7/0x19d0 net/sched/sch_generic.c:379 __dev_xmit_skb net/core/dev.c:3533 [inline] __dev_queue_xmit+0x16f1/0x3650 net/core/dev.c:3838 dev_queue_xmit+0x18/0x20 net/core/dev.c:3902 br_dev_queue_push_xmit+0x3f3/0x5c0 net/bridge/br_forward.c:52 NF_HOOK include/linux/netfilter.h:305 [inline] NF_HOOK include/linux/netfilter.h:299 [inline] br_forward_finish+0xfa/0x400 net/bridge/br_forward.c:65 NF_HOOK include/linux/netfilter.h:305 [inline] NF_HOOK include/linux/netfilter.h:299 [inline] __br_forward+0x641/0xb00 net/bridge/br_forward.c:109 deliver_clone+0x61/0xc0 net/bridge/br_forward.c:125 maybe_deliver+0x2c7/0x390 net/bridge/br_forward.c:181 br_flood+0x13a/0x3d0 net/bridge/br_forward.c:223 br_dev_xmit+0x98c/0x15a0 net/bridge/br_device.c:100 __netdev_start_xmit include/linux/netdevice.h:4406 [inline] netdev_start_xmit include/linux/netdevice.h:4420 [inline] xmit_one net/core/dev.c:3280 [inline] dev_hard_start_xmit+0x1a3/0x9c0 net/core/dev.c:3296 __dev_queue_xmit+0x2b15/0x3650 net/core/dev.c:3869 dev_queue_xmit+0x18/0x20 net/core/dev.c:3902 neigh_resolve_output net/core/neighbour.c:1490 [inline] neigh_resolve_output+0x5a5/0x970 net/core/neighbour.c:1470 neigh_output include/net/neighbour.h:511 [inline] ip6_finish_output2+0x1034/0x2520 net/ipv6/ip6_output.c:116 __ip6_finish_output+0x444/0xa50 net/ipv6/ip6_output.c:142 ip6_finish_output+0x38/0x1f0 net/ipv6/ip6_output.c:152 NF_HOOK_COND include/linux/netfilter.h:294 [inline] ip6_output+0x235/0x7c0 net/ipv6/ip6_output.c:175 dst_output include/net/dst.h:436 [inline] NF_HOOK include/linux/netfilter.h:305 [inline] NF_HOOK include/linux/netfilter.h:299 [inline] mld_sendpack+0x9c7/0xea0 net/ipv6/mcast.c:1682 mld_send_cr net/ipv6/mcast.c:1978 [inline] mld_ifc_timer_expire+0x449/0x8a0 net/ipv6/mcast.c:2477 call_timer_fn+0x1ac/0x780 kernel/time/timer.c:1322 expire_timers kernel/time/timer.c:1366 [inline] __run_timers kernel/time/timer.c:1685 [inline] __run_timers kernel/time/timer.c:1653 [inline] run_timer_softirq+0x697/0x17a0 kernel/time/timer.c:1698 __do_softirq+0x262/0x98c kernel/softirq.c:292 invoke_softirq kernel/softirq.c:373 [inline] irq_exit+0x19b/0x1e0 kernel/softirq.c:413 exiting_irq arch/x86/include/asm/apic.h:537 [inline] smp_apic_timer_interrupt+0x1a3/0x610 arch/x86/kernel/apic/apic.c:1133 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830 RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:26 [inline] RIP: 0010:check_kcov_mode kernel/kcov.c:68 [inline] RIP: 0010:write_comp_data+0x9/0x70 kernel/kcov.c:123 Code: 12 00 00 8b 80 f4 12 00 00 48 8b 11 48 83 c2 01 48 39 d0 76 07 48 89 34 d1 48 89 11 5d c3 0f 1f 00 65 4c 8b 04 25 40 fe 01 00 <65> 8b 05 b8 88 8f 7e a9 00 01 1f 00 75 51 41 8b 80 f0 12 00 00 83 RSP: 0018:ffff88807912f310 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff81ff17f5 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000007 RBP: ffff88807912f318 R08: ffff888059cd8700 R09: fffffbfff134afb0 R10: fffffbfff134afaf R11: ffffffff89a57d7f R12: ffffea00014e3f88 R13: ffffea00014e3f80 R14: ffffea00014e3f48 R15: ffffea00014e3f80 compound_head include/linux/page-flags.h:176 [inline] PageLocked include/linux/page-flags.h:312 [inline] ext4_bio_write_page+0x125/0x1722 fs/ext4/page-io.c:418 mpage_submit_page+0x15a/0x270 fs/ext4/inode.c:2253 mpage_map_and_submit_buffers+0x52c/0x8a0 fs/ext4/inode.c:2450 mpage_map_and_submit_extent fs/ext4/inode.c:2584 [inline] ext4_writepages+0x1ada/0x2ec0 fs/ext4/inode.c:2897 do_writepages+0xfa/0x2a0 mm/page-writeback.c:2342 __filemap_fdatawrite_range+0x26d/0x340 mm/filemap.c:415 file_write_and_wait_range+0x9a/0x100 mm/filemap.c:773 __generic_file_fsync+0x79/0x200 fs/libfs.c:996 ext4_sync_file+0x89a/0x15c0 fs/ext4/fsync.c:120 vfs_fsync_range+0x141/0x230 fs/sync.c:197 generic_write_sync include/linux/fs.h:2799 [inline] ext4_file_write_iter+0x839/0x1430 fs/ext4/file.c:281 call_write_iter include/linux/fs.h:1870 [inline] new_sync_write+0x4d3/0x770 fs/read_write.c:483 __vfs_write+0xe1/0x110 fs/read_write.c:496 vfs_write+0x268/0x5d0 fs/read_write.c:558 ksys_write+0x14f/0x290 fs/read_write.c:611 __do_sys_write fs/read_write.c:623 [inline] __se_sys_write fs/read_write.c:620 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:620 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4598e9 Code: fd b7 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fa14d42cc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004598e9 RDX: 00000000ffffff05 RSI: 0000000020000240 RDI: 0000000000000003 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fa14d42d6d4 R13: 00000000004c9a89 R14: 00000000004e1190 R15: 00000000ffffffff