syzbot


INFO: task hung in synchronize_rcu (3)

Status: upstream: reported C repro on 2024/07/26 03:55
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+e52148e52e5075da44cc@syzkaller.appspotmail.com
First crash: 577d, last: 2d11h
Bug presence (2)
Date Name Commit Repro Result
2026/02/10 linux-5.15.y (ToT) 7b232985052f C [report] INFO: task hung in synchronize_rcu
2026/02/10 upstream (ToT) 72c395024dac C Didn't crash
Similar bugs (15)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in synchronize_rcu (3) 1 C done done 374 1104d 2041d 22/29 fixed on 2023/02/24 13:50
linux-6.1 INFO: task hung in synchronize_rcu origin:lts-only 1 C unreliable 26 50d 1059d 0/3 upstream: reported C repro on 2023/04/01 04:49
android-49 INFO: task hung in synchronize_rcu 1 1 2278d 2277d 0/3 auto-closed as invalid on 2020/03/28 16:57
linux-4.14 INFO: task hung in synchronize_rcu vfs 1 C error 162 1118d 2300d 0/1 upstream: reported C repro on 2019/11/07 04:32
linux-4.19 INFO: task hung in synchronize_rcu 1 C error 70 1108d 2298d 0/1 upstream: reported C repro on 2019/11/08 21:27
linux-5.15 INFO: task hung in synchronize_rcu 1 1 1044d 1044d 0/3 auto-obsoleted due to no activity on 2023/08/14 02:05
android-6-12 INFO: task hung in synchronize_rcu 1 41 103d 226d 0/1 auto-obsoleted due to no activity on 2026/01/01 15:51
upstream INFO: task hung in synchronize_rcu 1 syz done 1206 2278d 2304d 14/29 fixed on 2019/11/29 15:48
upstream INFO: task hung in synchronize_rcu (4) net fs 1 C done error 2552 2d12h 1026d 0/29 upstream: reported C repro on 2023/05/04 02:01
linux-5.15 INFO: task hung in synchronize_rcu (2) 1 1 733d 733d 0/3 auto-obsoleted due to no activity on 2024/05/31 13:53
android-414 INFO: task hung in synchronize_rcu 1 1 2296d 2296d 0/1 auto-closed as invalid on 2020/03/10 10:42
upstream INFO: task hung in synchronize_rcu (2) trace 1 8 2277d 2277d 0/29 closed as invalid on 2019/11/30 16:54
linux-6.6 INFO: task hung in synchronize_rcu 1 4 38d 115d 0/2 upstream: reported on 2025/10/30 17:16
android-6-12 INFO: task hung in synchronize_rcu (2) 1 3 1d01h 8d23h 0/1 premoderation: reported on 2026/02/14 17:59
upstream INFO: task hung in rtnetlink_rcv_msg net 1 C inconclusive inconclusive 1970 594d 2558d 26/29 fixed on 2024/07/09 19:14
Last patch testing requests (8)
Created Duration User Patch Repo Result
2026/02/04 03:53 11m retest repro linux-5.15.y error
2026/02/04 03:53 46m retest repro linux-5.15.y report log
2025/12/23 02:34 15m retest repro linux-5.15.y report log
2025/12/23 02:34 14m retest repro linux-5.15.y report log
2025/11/25 20:29 14m retest repro linux-5.15.y report log
2025/11/25 20:29 13m retest repro linux-5.15.y report log
2025/10/13 12:47 14m retest repro linux-5.15.y report log
2025/10/13 12:47 18m retest repro linux-5.15.y report log
Fix bisection attempts (8)
Created Duration User Patch Repo Result
2026/02/11 22:21 6m fix candidate upstream error job log
2026/01/20 15:22 2m fix candidate upstream error job log
2025/12/12 00:00 1m fix candidate upstream error job log
2025/11/04 03:37 2m fix candidate upstream error job log
2025/07/26 19:38 6m fix candidate upstream error job log
2025/02/16 10:12 2m fix candidate upstream error job log
2024/10/15 06:09 0m fix candidate upstream error job log
2024/08/29 04:18 1m fix candidate upstream error job log

Sample crash report:
INFO: task syz-executor:4319 blocked for more than 148 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:22000 pid: 4319 ppid:     1 flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 exp_funnel_lock kernel/rcu/tree_exp.h:313 [inline]
 synchronize_rcu_expedited+0x680/0x750 kernel/rcu/tree_exp.h:845
 __tun_detach+0x81f/0x1500 drivers/net/tun.c:670
 tun_detach drivers/net/tun.c:702 [inline]
 tun_chr_close+0x109/0x1b0 drivers/net/tun.c:3440
 __fput+0x234/0x930 fs/file_table.c:311
 task_work_run+0x125/0x1a0 kernel/task_work.c:188
 exit_task_work include/linux/task_work.h:33 [inline]
 do_exit+0x626/0x20c0 kernel/exit.c:883
 do_group_exit+0x12e/0x300 kernel/exit.c:997
 get_signal+0x6ca/0x12c0 kernel/signal.c:2900
 arch_do_signal_or_restart+0xe7/0x12c0 arch/x86/kernel/signal.c:867
 handle_signal_work kernel/entry/common.c:154 [inline]
 exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:178
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f0ca3ee72bb
RSP: 002b:00007ffc346e8dd0 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffed RBX: 0000000000000005 RCX: 00007f0ca3ee72bb
RDX: 00007ffc346e8e30 RSI: 0000000000008933 RDI: 0000000000000005
RBP: 00007f0ca3f7e4d3 R08: 0000000000000000 R09: 00007ffc346e9150
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 00007f0ca4c8f620 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
INFO: task syz-executor:4431 blocked for more than 149 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:27152 pid: 4431 ppid:     1 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6537
 __mutex_lock_common+0xcfc/0x2400 kernel/locking/mutex.c:669
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 rtnl_lock net/core/rtnetlink.c:72 [inline]
 rtnetlink_rcv_msg+0x7ee/0xf30 net/core/rtnetlink.c:5681
 netlink_rcv_skb+0x1f5/0x440 net/netlink/af_netlink.c:2507
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x774/0x920 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x8ba/0xbe0 net/netlink/af_netlink.c:1918
 sock_sendmsg_nosec net/socket.c:706 [inline]
 __sock_sendmsg net/socket.c:718 [inline]
 __sys_sendto+0x46d/0x620 net/socket.c:2072
 __do_sys_sendto net/socket.c:2084 [inline]
 __se_sys_sendto net/socket.c:2080 [inline]
 __x64_sys_sendto+0xda/0xf0 net/socket.c:2080
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f891d78fece
RSP: 002b:00007ffce7767bf8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 000055555c70d500 RCX: 00007f891d78fece
RDX: 0000000000000028 RSI: 00007f891e577670 RDI: 0000000000000003
RBP: 0000000000000001 R08: 00007ffce7767c74 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f891e577670 R15: 0000000000000000
 </TASK>

Showing all locks held in the system:
2 locks held by kworker/0:0/7:
 #0: ffff888016c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc90000cc7d00 (free_ipc_work){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
3 locks held by kworker/1:0/21:
1 lock held by khungtaskd/27:
 #0: ffffffff8c31eaa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
3 locks held by kworker/u4:1/144:
 #0: ffff8880b903a358 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x26/0x140 kernel/sched/core.c:475
 #1: ffffc9000112fd00 ((work_completion)(&(&forw_packet_aggr->delayed_work)->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: ffff88802ba35fd8 (key#18){+...}-{2:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312
4 locks held by kworker/u4:3/155:
 #0: ffff888016dcd938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc90001ed7d00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: ffffffff8d430950 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x148/0xba0 net/core/net_namespace.c:589
 #3: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: cleanup_net+0x60e/0xba0 net/core/net_namespace.c:625
3 locks held by kworker/0:2/1108:
 #0: ffff88802acca538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc9000524fd00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_dad_work+0xca/0x1540 net/ipv6/addrconf.c:4110
2 locks held by getty/3944:
 #0: ffff88807f579098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc90002cf62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x5df/0x1a70 drivers/tty/n_tty.c:2158
3 locks held by kworker/1:3/4212:
 #0: ffff88802acca538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc90002e5fd00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_dad_work+0xca/0x1540 net/ipv6/addrconf.c:4110
4 locks held by kworker/u5:2/4215:
 #0: ffff88805d168938 ((wq_completion)hci14#2){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc90002f0fd00 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: ffff888075e34078 (&hdev->lock){+.+.}-{3:3}, at: le_conn_complete_evt+0xaf/0x15c0 net/bluetooth/hci_event.c:5326
 #3: ffffffff8d582a28 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_connect_cfm include/net/bluetooth/hci_core.h:1502 [inline]
 #3: ffffffff8d582a28 (hci_cb_list_lock){+.+.}-{3:3}, at: le_conn_complete_evt+0xcdf/0x15c0 net/bluetooth/hci_event.c:5459
3 locks held by kworker/0:7/4291:
 #0: ffff888016c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc9000300fd00 (deferred_process_work){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: switchdev_deferred_process_work+0xa/0x20 net/switchdev/switchdev.c:74
3 locks held by kworker/0:19/4303:
 #0: ffff888016c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc900030bfd00 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: ffff88807a010240 (&data->fib_lock){+.+.}-{3:3}, at: nsim_fib_event_work+0x26a/0x33e0 drivers/net/netdevsim/fib.c:1480
1 lock held by syz-executor/4313:
 #0: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: netdev_wait_allrefs net/core/dev.c:10587 [inline]
 #0: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: netdev_run_todo+0x59d/0xa70 net/core/dev.c:10694
3 locks held by syz-executor/4314:
 #0: ffff88802547cff0 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close+0x5f/0x1030 net/bluetooth/hci_core.c:1737
 #1: ffff88802547c078 (&hdev->lock){+.+.}-{3:3}, at: hci_dev_do_close+0x3f4/0x1030 net/bluetooth/hci_core.c:1782
 #2: ffffffff8d582a28 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:1517 [inline]
 #2: ffffffff8d582a28 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_hash_flush+0xa4/0x220 net/bluetooth/hci_conn.c:1622
2 locks held by syz-executor/4319:
 #0: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: tun_detach drivers/net/tun.c:699 [inline]
 #0: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: tun_chr_close+0x3d/0x1b0 drivers/net/tun.c:3440
 #1: ffffffff8c323528 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:322 [inline]
 #1: ffffffff8c323528 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3a5/0x750 kernel/rcu/tree_exp.h:845
3 locks held by syz-executor/4320:
 #0: ffff88807e3b0ff0 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close+0x5f/0x1030 net/bluetooth/hci_core.c:1737
 #1: ffff88807e3b0078 (&hdev->lock){+.+.}-{3:3}, at: hci_dev_do_close+0x3f4/0x1030 net/bluetooth/hci_core.c:1782
 #2: ffffffff8d582a28 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:1517 [inline]
 #2: ffffffff8d582a28 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_hash_flush+0xa4/0x220 net/bluetooth/hci_conn.c:1622
3 locks held by kworker/1:5/4351:
2 locks held by syz-executor/4376:
 #0: ffff88807e384ff0 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close+0x5f/0x1030 net/bluetooth/hci_core.c:1737
 #1: ffff88807e384078 (&hdev->lock){+.+.}-{3:3}, at: hci_dev_do_close+0x3f4/0x1030 net/bluetooth/hci_core.c:1782
3 locks held by kworker/1:8/4394:
 #0: ffff888016c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc9000355fd00 (reg_work){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: reg_todo+0x18/0x1aa0 net/wireless/reg.c:3165
3 locks held by kworker/u4:9/4401:
 #0: ffff888016c79138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
 #1: ffffc900034dfd00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
 #2: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xa/0x50 net/core/link_watch.c:251
3 locks held by syz-executor/4413:
 #0: ffff88801f714ff0 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close+0x5f/0x1030 net/bluetooth/hci_core.c:1737
 #1: ffff88801f714078 (&hdev->lock){+.+.}-{3:3}, at: hci_dev_do_close+0x3f4/0x1030 net/bluetooth/hci_core.c:1782
 #2: ffffffff8d582a28 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:1517 [inline]
 #2: ffffffff8d582a28 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_hash_flush+0xa4/0x220 net/bluetooth/hci_conn.c:1622
3 locks held by syz-executor/4423:
 #0: ffff888022b1cff0 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close+0x5f/0x1030 net/bluetooth/hci_core.c:1737
 #1: ffff888022b1c078 (&hdev->lock){+.+.}-{3:3}, at: hci_dev_do_close+0x3f4/0x1030 net/bluetooth/hci_core.c:1782
 #2: ffffffff8d582a28 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:1517 [inline]
 #2: ffffffff8d582a28 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_hash_flush+0xa4/0x220 net/bluetooth/hci_conn.c:1622
1 lock held by syz-executor/4431:
 #0: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ee/0xf30 net/core/rtnetlink.c:5681
1 lock held by syz-executor/4445:
 #0: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ee/0xf30 net/core/rtnetlink.c:5681
1 lock held by syz-executor/4450:
 #0: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ee/0xf30 net/core/rtnetlink.c:5681
1 lock held by syz-executor/4469:
 #0: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ee/0xf30 net/core/rtnetlink.c:5681
4 locks held by syz.0.74/4471:
 #0: ffff888075e30ff0 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close+0x5f/0x1030 net/bluetooth/hci_core.c:1737
 #1: ffff888075e30078 (&hdev->lock){+.+.}-{3:3}, at: hci_dev_do_close+0x3f4/0x1030 net/bluetooth/hci_core.c:1782
 #2: ffffffff8d582a28 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:1517 [inline]
 #2: ffffffff8d582a28 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_hash_flush+0xa4/0x220 net/bluetooth/hci_conn.c:1622
 #3: ffffffff8c323528 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:322 [inline]
 #3: ffffffff8c323528 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3a5/0x750 kernel/rcu/tree_exp.h:845
1 lock held by syz-executor/4488:
 #0: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ee/0xf30 net/core/rtnetlink.c:5681
1 lock held by syz-executor/4489:
 #0: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ee/0xf30 net/core/rtnetlink.c:5681
1 lock held by syz-executor/4490:
 #0: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ee/0xf30 net/core/rtnetlink.c:5681
1 lock held by syz-executor/4491:
 #0: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ee/0xf30 net/core/rtnetlink.c:5681
1 lock held by syz-executor/4492:
 #0: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d43c848 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ee/0xf30 net/core/rtnetlink.c:5681

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

NMI backtrace for cpu 1
CPU: 1 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline]
 watchdog+0xe0f/0xe50 kernel/hung_task.c:369
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4302 Comm: kworker/0:18 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Workqueue: events nsim_dev_trap_report_work
RIP: 0010:memset_erms+0xe/0x10 arch/x86/lib/memset_64.S:66
Code: b6 f6 48 b8 01 01 01 01 01 01 01 01 48 0f af c6 f3 48 ab 89 d1 f3 aa 4c 89 c8 c3 90 49 89 f9 40 88 f0 48 89 d1 f3 aa 4c 89 c8 <c3> 90 49 89 fa 40 0f b6 ce 48 b8 01 01 01 01 01 01 01 01 48 0f af
RSP: 0018:ffffc900030af6c0 EFLAGS: 00000202
RAX: ffffc900030af7d8 RBX: ffffc900030af788 RCX: 0000000000000000
RDX: 0000000000000010 RSI: 0000000000000000 RDI: ffffc900030af7e8
RBP: ffffc900030af7d0 R08: ffffc900030af7e7 R09: ffffc900030af7d8
R10: dffffc0000000000 R11: fffff52000615efd R12: 1ffffffff1c0983d
R13: dffffc0000000000 R14: ffffc900030af7d8 R15: ffffc900030af7bd
FS:  0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd010e42f8 CR3: 000000002adcd000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 unwind_next_frame+0xa3d/0x1d90 arch/x86/kernel/unwind_orc.c:547
 arch_stack_walk+0x10c/0x140 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xa6/0xf0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 ____kasan_kmalloc mm/kasan/common.c:513 [inline]
 __kasan_kmalloc+0xb5/0xf0 mm/kasan/common.c:522
 kmalloc_reserve net/core/skbuff.c:356 [inline]
 __alloc_skb+0x22c/0x750 net/core/skbuff.c:427
 alloc_skb include/linux/skbuff.h:1162 [inline]
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:664 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:721 [inline]
 nsim_dev_trap_report_work+0x2a1/0xb40 drivers/net/netdevsim/dev.c:762
 process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
 worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Crashes (18):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/21 05:47 linux-5.15.y 3330a8d33e08 6e7b5511 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in synchronize_rcu
2026/02/14 23:45 linux-5.15.y e45d5d41c134 1e62d198 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-5-15-kasan INFO: task hung in synchronize_rcu
2026/02/07 15:25 linux-5.15.y 7b232985052f f20fc9f9 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-5-15-kasan INFO: task hung in synchronize_rcu
2025/03/27 02:36 linux-5.15.y 0c935c049b5c 20510e88 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-5-15-kasan-arm64 INFO: task hung in synchronize_rcu
2025/03/15 15:16 linux-5.15.y 0c935c049b5c e2826670 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-5-15-kasan-arm64 INFO: task hung in synchronize_rcu
2025/02/28 01:48 linux-5.15.y c16c81c81336 6a8fcbc4 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-5-15-kasan-arm64 INFO: task hung in synchronize_rcu
2024/07/27 03:46 linux-5.15.y 7c6d66f0266f 46eb10b7 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-5-15-kasan-arm64 INFO: task hung in synchronize_rcu
2025/11/09 10:20 linux-5.15.y cc5ec8769306 4e1406b4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in synchronize_rcu
2025/07/14 07:27 linux-5.15.y 2f693b607545 3cda49cf .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in synchronize_rcu
2024/12/08 18:57 linux-5.15.y 0a51d2d4527b 9ac0fdc6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in synchronize_rcu
2024/11/05 22:10 linux-5.15.y 72244eab0dad da38b4c9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in synchronize_rcu
2024/09/28 21:35 linux-5.15.y 3a5928702e71 ba29ff75 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in synchronize_rcu
2024/09/13 20:26 linux-5.15.y 3a5928702e71 b58f933c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in synchronize_rcu
2024/09/11 03:53 linux-5.15.y 14e468424d3e 8ab55d0e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: task hung in synchronize_rcu
2024/08/02 15:21 linux-5.15.y 7e89efd3ae1c 1e9c4cf3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in synchronize_rcu
2024/07/26 03:55 linux-5.15.y 7c6d66f0266f 3f86dfed .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in synchronize_rcu
2024/08/30 07:35 linux-5.15.y fa93fa65db6e ee2602b8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: task hung in synchronize_rcu
2024/08/29 07:07 linux-5.15.y fa93fa65db6e ef3de9e8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: task hung in synchronize_rcu
* Struck through repros no longer work on HEAD.