syzbot


INFO: task hung in lock_sock_nested

Status: upstream: reported on 2026/03/09 17:42
Reported-by: syzbot+0bb1f3d36dfd646beeab@syzkaller.appspotmail.com
First crash: 17h44m, last: 17h44m
Similar bugs (18)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in lock_sock_nested (2) net virt kvm 1 C done 418 2194d 2207d 15/29 fixed on 2020/04/15 17:19
upstream INFO: task hung in lock_sock_nested kvm net virt 1 C 2593 2212d 3011d 0/29 closed as dup on 2017/12/23 20:15
android-44 INFO: task hung in lock_sock_nested (2) 1 4 2294d 2390d 0/2 auto-closed as invalid on 2020/03/27 01:37
linux-4.19 INFO: task hung in lock_sock_nested (3) 1 6 1141d 1355d 0/1 upstream: reported on 2022/06/23 22:52
upstream INFO: task hung in lock_sock_nested (3) net 1 C done 5 1983d 1984d 15/29 fixed on 2020/11/16 12:12
android-49 INFO: task hung in lock_sock_nested (2) 1 2 2372d 2491d 0/3 auto-closed as invalid on 2020/01/08 15:18
linux-4.14 INFO: task hung in lock_sock_nested 1 1 2314d 2314d 0/1 auto-closed as invalid on 2020/03/06 15:38
linux-4.14 INFO: task hung in lock_sock_nested (2) 1 1 2052d 2052d 0/1 auto-closed as invalid on 2020/11/24 03:07
android-44 INFO: task hung in lock_sock_nested 1 C 82 2932d 2934d 0/2 closed as invalid on 2019/03/08 00:11
upstream INFO: task can't die in __lock_sock bluetooth 1 C done error 1067 853d 1667d 0/29 auto-obsoleted due to no activity on 2024/01/16 13:36
upstream INFO: task hung in lock_sock_nested (5) mptcp tipc 1 C done 43 317d 439d 28/29 fixed on 2025/05/06 15:33
upstream INFO: task hung in lock_sock_nested (4) mptcp 1 C done 6 1877d 1924d 19/29 fixed on 2021/03/10 01:48
android-49 INFO: task hung in lock_sock_nested 1 C 101 2571d 2934d 0/3 closed as invalid on 2019/03/08 00:11
android-414 INFO: task hung in lock_sock_nested 1 65 2338d 2523d 0/1 auto-closed as invalid on 2020/02/12 04:11
linux-4.19 INFO: task hung in lock_sock_nested (2) 1 1 1551d 1551d 0/1 auto-closed as invalid on 2022/04/08 17:15
linux-5.15 INFO: task hung in lock_sock_nested 1 1 574d 574d 0/3 auto-obsoleted due to no activity on 2024/11/21 04:55
linux-4.19 INFO: task hung in lock_sock_nested 1 1 2131d 2131d 0/1 auto-closed as invalid on 2020/09/05 19:53
linux-6.6 INFO: task hung in lock_sock_nested 1 1 69d 69d 0/2 upstream: reported on 2025/12/31 07:35

Sample crash report:
INFO: task syz.0.420:6135 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.420       state:D stack:0     pid:6135  ppid:4325   flags:0x00000009
Call trace:
 __switch_to+0x2f4/0x550 arch/arm64/kernel/process.c:555
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0xdd0/0x1b0c kernel/sched/core.c:6562
 schedule+0xc4/0x170 kernel/sched/core.c:6638
 __lock_sock+0x10c/0x264 net/core/sock.c:2920
 lock_sock_nested+0xb8/0x130 net/core/sock.c:3501
 lock_sock include/net/sock.h:1805 [inline]
 tipc_send_group_bcast+0x464/0xacc net/tipc/socket.c:1100
 __tipc_sendmsg+0x2ac/0x28b8 net/tipc/socket.c:1436
 tipc_sendmsg+0x60/0x1bc net/tipc/socket.c:1403
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 sock_write_iter+0x268/0x360 net/socket.c:1143
 call_write_iter include/linux/fs.h:2265 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x3ec/0x7f0 fs/read_write.c:584
 ksys_write+0x12c/0x224 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __arm64_sys_write+0x7c/0x90 fs/read_write.c:646
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
 #0: ffff8000153e7c30 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x40/0xbb4 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffff8000153e8450 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x40/0xbb4 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/28:
 #0: ffff8000153e72c0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0xc/0x44 include/linux/rcupdate.h:349
2 locks held by kworker/1:2/112:
 #0: ffff0000c0021938 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x6b8/0x13a4 kernel/workqueue.c:2265
 #1: ffff8000205b7c20 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work+0x6fc/0x13a4 kernel/workqueue.c:2267
2 locks held by getty/4078:
 #0: ffff0000d656e098 (&tty->ldisc_sem){++++}-{0:0}, at: ldsem_down_read+0x3c/0x4c drivers/tty/tty_ldsem.c:340
 #1: ffff8000207eb2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x2ec/0xfa0 drivers/tty/n_tty.c:2198
3 locks held by kworker/1:11/5727:
 #0: ffff0000c0020938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x6b8/0x13a4 kernel/workqueue.c:2265
 #1: ffff800022477c20 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work+0x6fc/0x13a4 kernel/workqueue.c:2267
 #2: ffff0000cc19b240 (&data->fib_lock){+.+.}-{3:3}, at: nsim_fib_event_work+0x1d0/0x27cc drivers/net/netdevsim/fib.c:1491
2 locks held by kworker/u4:16/5872:
 #0: ffff0000c0029138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x6b8/0x13a4 kernel/workqueue.c:2265
 #1: ffff8000217b7c20 ((work_completion)(&map->work)){+.+.}-{0:0}, at: process_one_work+0x6fc/0x13a4 kernel/workqueue.c:2267
1 lock held by syz.0.420/6134:
1 lock held by syz.0.420/6135:
 #0: ffff0000d248dc30 (sk_lock-AF_TIPC){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1805 [inline]
 #0: ffff0000d248dc30 (sk_lock-AF_TIPC){+.+.}-{0:0}, at: tipc_send_group_bcast+0x464/0xacc net/tipc/socket.c:1100
1 lock held by syz-executor/6387:
 #0: ffff8000153ecf78 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:323 [inline]
 #0: ffff8000153ecf78 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x2b8/0x77c kernel/rcu/tree_exp.h:962
3 locks held by kworker/u4:20/8978:
1 lock held by syz.3.1159/9154:
1 lock held by syz.4.1161/9161:
 #0: ffff8000153ecf78 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:291 [inline]
 #0: ffff8000153ecf78 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3fc/0x77c kernel/rcu/tree_exp.h:962
2 locks held by syz.2.1163/9168:
 #0: ffff8000178db290 (cb_lock){++++}-{3:3}, at: genl_rcv+0x28/0x50 net/netlink/genetlink.c:860
 #1: ffff8000153ece40 (rcu_state.barrier_mutex){+.+.}-{3:3}, at: rcu_barrier+0x58/0x5d0 kernel/rcu/tree.c:4023

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


Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/09 17:42 linux-6.1.y f2ddafa93a25 176bead5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 INFO: task hung in lock_sock_nested
* Struck through repros no longer work on HEAD.