syzbot

INFO: task kworker/u8:2:42 blocked for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:2    state:D stack:21136 pid:42    tgid:42    ppid:2      task_flags:0x4208160 flags:0x00080000
Workqueue: events_unbound bpf_map_free_deferred
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x1553/0x5240 kernel/sched/core.c:6908
 __schedule_loop kernel/sched/core.c:6990 [inline]
 rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7286
 rt_mutex_slowlock_block+0x508/0x680 kernel/locking/rtmutex.c:1647
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1721 [inline]
 __rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1760 [inline]
 rt_mutex_slowlock+0x2dc/0x7b0 kernel/locking/rtmutex.c:1800
 __rt_mutex_lock kernel/locking/rtmutex.c:1815 [inline]
 __mutex_lock_common kernel/locking/rtmutex_api.c:534 [inline]
 mutex_lock_nested+0x168/0x1d0 kernel/locking/rtmutex_api.c:552
 rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
 dev_map_free+0x11f/0x6a0 kernel/bpf/devmap.c:216
 bpf_map_free kernel/bpf/syscall.c:892 [inline]
 bpf_map_free_deferred+0x217/0x460 kernel/bpf/syscall.c:919
 process_one_work kernel/workqueue.c:3275 [inline]
 process_scheduled_works+0xb02/0x1830 kernel/workqueue.c:3358
 worker_thread+0xa50/0xfc0 kernel/workqueue.c:3439
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Showing all locks held in the system:
3 locks held by kworker/0:0/9:
9 locks held by kworker/u8:0/12:
4 locks held by ksoftirqd/1/30:
1 lock held by khungtaskd/37:
 #0: ffffffff8ddcb880 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #0: ffffffff8ddcb880 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #0: ffffffff8ddcb880 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
3 locks held by kworker/u8:2/42:
 #0: ffff888019c44138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3250 [inline]
 #0: ffff888019c44138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x9ea/0x1830 kernel/workqueue.c:3358
 #1: ffffc90000b47c40 ((work_completion)(&map->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3251 [inline]
 #1: ffffc90000b47c40 ((work_completion)(&map->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa25/0x1830 kernel/workqueue.c:3358
 #2: ffffffff8ddd1af0 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
2 locks held by kworker/u8:6/160:
 #0: ffff88801c3e5938 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3250 [inline]
 #0: ffff88801c3e5938 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_scheduled_works+0x9ea/0x1830 kernel/workqueue.c:3358
 #1: ffffc90003b47c40 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3251 [inline]
 #1: ffffc90003b47c40 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_scheduled_works+0xa25/0x1830 kernel/workqueue.c:3358
5 locks held by kworker/u8:9/1169:
3 locks held by kworker/u8:13/3563:
 #0: ffff8880324ac938 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3250 [inline]
 #0: ffff8880324ac938 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x9ea/0x1830 kernel/workqueue.c:3358
 #1: ffffc9000eb87c40 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3251 [inline]
 #1: ffffc9000eb87c40 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa25/0x1830 kernel/workqueue.c:3358
 #2: ffffffff8f15a0f8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #2: ffffffff8f15a0f8 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_verify_work+0x19/0x30 net/ipv6/addrconf.c:4738
3 locks held by kworker/u8:14/3593:
 #0: ffff888019c44138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3250 [inline]
 #0: ffff888019c44138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x9ea/0x1830 kernel/workqueue.c:3358
 #1: ffffc9000ecd7c40 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3251 [inline]
 #1: ffffc9000ecd7c40 ((linkwatch_work).work){+.+.}-{0:0}, at: process_scheduled_works+0xa25/0x1830 kernel/workqueue.c:3358
 #2: ffffffff8f15a0f8 (rtnl_mutex){+.+.}-{4:4}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:313
2 locks held by getty/5553:
 #0: ffff88803758d0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90003e7e2e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x462/0x13c0 drivers/tty/n_tty.c:2211
1 lock held by syz.0.5852/18419:
 #0: ffffffff8ddd1af0 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
1 lock held by syz.2.5880/18480:
 #0: ffffffff8ddd1af0 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
1 lock held by syz-executor/18500:
 #0: ffffffff8ddd1af0 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
1 lock held by syz-executor/18535:
 #0: ffffffff8ddd1af0 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
2 locks held by kworker/u8:1/18576:
 #0: ffff88801c3e5938 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3250 [inline]
 #0: ffff88801c3e5938 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_scheduled_works+0x9ea/0x1830 kernel/workqueue.c:3358
 #1: ffffc9000eef7c40 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3251 [inline]
 #1: ffffc9000eef7c40 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_scheduled_works+0xa25/0x1830 kernel/workqueue.c:3358
1 lock held by syz-executor/18661:
 #0: ffffffff8ddd1af0 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
1 lock held by syz.4.5946/18662:
 #0: ffffffff8ddd1af0 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
2 locks held by syz-executor/18677:
 #0: ffffffff8f6c1430 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #0: ffffffff8f6c1430 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #0: ffffffff8f6c1430 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250 net/core/rtnetlink.c:570
 #1: ffffffff8ddd1af0 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
1 lock held by syz-executor/18686:
 #0: ffffffff8ddd1af0 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
1 lock held by syz-executor/18690:
 #0: ffffffff8f15a0f8 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:634 [inline]
 #0: ffffffff8f15a0f8 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x41/0x1c0 drivers/net/tun.c:3436
1 lock held by syz-executor/18744:
 #0: ffffffff8f15a0f8 (rtnl_mutex){+.+.}-{4:4}, at: __tun_chr_ioctl+0x3bf/0x1e10 drivers/net/tun.c:3078
2 locks held by syz-executor/18749:
 #0: ffffffff8f14b940 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x4f7/0x730 net/core/net_namespace.c:577
 #1: ffffffff8f15a0f8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock_killable include/linux/rtnetlink.h:145 [inline]
 #1: ffffffff8f15a0f8 (rtnl_mutex){+.+.}-{4:4}, at: register_netdev+0x18/0x60 net/core/dev.c:11537
2 locks held by syz-executor/18771:
 #0: ffffffff8f14b940 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x4f7/0x730 net/core/net_namespace.c:577
 #1: ffffffff8f15a0f8 (rtnl_mutex){+.+.}-{4:4}, at: ip_tunnel_init_net+0x2d7/0x840 net/ipv4/ip_tunnel.c:1146
2 locks held by syz-executor/18772:
 #0: ffffffff8f14b940 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x4f7/0x730 net/core/net_namespace.c:577
 #1: ffffffff8f15a0f8 (rtnl_mutex){+.+.}-{4:4}, at: ip_tunnel_init_net+0x2d7/0x840 net/ipv4/ip_tunnel.c:1146
1 lock held by syz.3.5981/18798:
 #0: ffffffff8f15a0f8 (rtnl_mutex){+.+.}-{4:4}, at: __tun_chr_ioctl+0x3bf/0x1e10 drivers/net/tun.c:3078
1 lock held by dhcpcd/18800:
 #0: ffff888062c86358 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1709 [inline]
 #0: ffff888062c86358 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x33/0xe10 net/packet/af_packet.c:3197
1 lock held by dhcpcd/18801:
 #0: ffff888028b94358 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1709 [inline]
 #0: ffff888028b94358 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x33/0xe10 net/packet/af_packet.c:3197

=============================================

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 37 Comm: khungtaskd Tainted: G             L      syzkaller #0 PREEMPT_{RT,(full)} 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/27/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:161 [inline]
 __sys_info lib/sys_info.c:157 [inline]
 sys_info+0x135/0x170 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline]
 watchdog+0xfd9/0x1030 kernel/hung_task.c:515
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 12 Comm: kworker/u8:0 Tainted: G             L      syzkaller #0 PREEMPT_{RT,(full)} 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/27/2026
Workqueue: events_unbound nsim_dev_trap_report_work
RIP: 0010:fib_lookup+0x0/0x440 include/net/ip_fib.h:376
Code: 89 f7 e8 33 39 a9 f8 e9 9c fb ff ff 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <55> 41 57 41 56 41 55 41 54 53 50 49 89 d6 49 89 f5 49 89 fc 49 bf
RSP: 0018:ffffc90000116898 EFLAGS: 00000202
RAX: ffffffff8981ba9c RBX: ffffc90000116980 RCX: ffff88801c6b0000
RDX: ffffc90000116980 RSI: ffffc90000116b20 RDI: ffff88803ab8aac0
RBP: 1ffff92000022d69 R08: 0000000000000000 R09: 0000000000000100
R10: ffffc90000116980 R11: fffff52000022d36 R12: ffffc90000116b4c
R13: ffff88803ab8aac0 R14: 0000000000000000 R15: 1ffff92000022d64
FS:  0000000000000000(0000) GS:ffff88812633f000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000560ce54d1168 CR3: 000000000dbba000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 ip_route_output_key_hash_rcu+0x32e/0x25d0 net/ipv4/route.c:2814
 ip_route_output_key_hash+0x18d/0x2a0 net/ipv4/route.c:2705
 __ip_route_output_key include/net/route.h:169 [inline]
 ip_route_output_flow+0x2a/0x150 net/ipv4/route.c:2932
 ip_route_output_key include/net/route.h:179 [inline]
 ip_route_me_harder+0x742/0xf90 net/ipv4/netfilter.c:53
 synproxy_send_tcp+0x34c/0x670 net/netfilter/nf_synproxy_core.c:432
 synproxy_send_client_synack+0x8c1/0xe30 net/netfilter/nf_synproxy_core.c:485
 nft_synproxy_eval_v4+0x34a/0x4e0 net/netfilter/nft_synproxy.c:60
 nft_synproxy_do_eval+0x305/0x580 net/netfilter/nft_synproxy.c:142
 expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline]
 nft_do_chain+0x45e/0x1990 net/netfilter/nf_tables_core.c:285
 nft_do_chain_inet+0x29d/0x380 net/netfilter/nft_chain_filter.c:161
 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
 nf_hook_slow+0xc5/0x220 net/netfilter/core.c:623
 nf_hook include/linux/netfilter.h:273 [inline]
 NF_HOOK+0x21f/0x3c0 include/linux/netfilter.h:316
 NF_HOOK+0x336/0x3c0 include/linux/netfilter.h:318
 __netif_receive_skb_one_core net/core/dev.c:6164 [inline]
 __netif_receive_skb net/core/dev.c:6277 [inline]
 process_backlog+0x569/0xc60 net/core/dev.c:6628
 __napi_poll+0xaf/0x580 net/core/dev.c:7692
 napi_poll net/core/dev.c:7755 [inline]
 net_rx_action+0x696/0xe00 net/core/dev.c:7912
 handle_softirqs+0x1de/0x6f0 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 __local_bh_enable_ip+0x170/0x2b0 kernel/softirq.c:302
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 __alloc_skb+0x1aa/0x7d0 net/core/skbuff.c:697
 alloc_skb include/linux/skbuff.h:1383 [inline]
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:819 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:876 [inline]
 nsim_dev_trap_report_work+0x29f/0xbc0 drivers/net/netdevsim/dev.c:922
 process_one_work kernel/workqueue.c:3275 [inline]
 process_scheduled_works+0xb02/0x1830 kernel/workqueue.c:3358
 worker_thread+0xa50/0xfc0 kernel/workqueue.c:3439
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>