syzbot


INFO: task hung in __netlink_dump_start (2)

Status: upstream: reported on 2026/04/18 21:40
Reported-by: syzbot+06a499b54796d6bfed75@syzkaller.appspotmail.com
First crash: 2d16h, last: 2d16h
Similar bugs (10)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in __netlink_dump_start (2) net 1 5 1563d 1645d 0/29 closed as invalid on 2022/02/07 19:19
linux-4.19 INFO: task hung in __netlink_dump_start 1 1 2145d 2145d 0/1 auto-closed as invalid on 2020/10/04 12:25
upstream INFO: task hung in __netlink_dump_start net 1 2 2013d 2028d 0/29 auto-closed as invalid on 2021/01/13 23:36
linux-5.15 INFO: task hung in __netlink_dump_start 1 20 529d 793d 0/3 auto-obsoleted due to no activity on 2025/02/16 07:38
linux-4.19 INFO: task hung in __netlink_dump_start (2) 1 1 1516d 1516d 0/1 auto-closed as invalid on 2022/06/25 14:03
upstream INFO: task hung in rtnetlink_rcv_msg net 1 C inconclusive inconclusive 1970 651d 2614d 26/29 fixed on 2024/07/09 19:14
upstream INFO: task hung in __netlink_dump_start (3) net 1 3 549d 575d 0/29 auto-obsoleted due to no activity on 2025/01/17 03:09
upstream INFO: task hung in __netlink_dump_start (4) net 1 1 369d 369d 0/29 auto-obsoleted due to no activity on 2025/07/16 06:45
linux-6.1 INFO: task hung in __netlink_dump_start 1 16 668d 813d 0/3 auto-obsoleted due to no activity on 2024/09/29 18:06
linux-6.1 INFO: task hung in __netlink_dump_start (2) origin:lts-only 1 syz inconclusive 12 264d 567d 0/3 upstream: reported syz repro on 2024/10/01 03:35

Sample crash report:
INFO: task dhcpcd:3855 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:dhcpcd          state:D stack:25744 pid: 3855 ppid:     1 flags:0x00004202
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
 __netlink_dump_start+0x11f/0x700 net/netlink/af_netlink.c:2352
 netlink_dump_start include/linux/netlink.h:258 [inline]
 rtnetlink_rcv_msg+0xdd9/0xf30 net/core/rtnetlink.c:5643
 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_sendmsg+0x5b7/0x8f0 net/socket.c:2445
 ___sys_sendmsg+0x236/0x2e0 net/socket.c:2499
 __sys_sendmsg net/socket.c:2528 [inline]
 __do_sys_sendmsg net/socket.c:2537 [inline]
 __se_sys_sendmsg+0x1af/0x290 net/socket.c:2535
 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: 0033:0x7faf01f6f407
RSP: 002b:00007fff016ec8d0 EFLAGS: 00000202 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007faf01ee5740 RCX: 00007faf01f6f407
RDX: 0000000000000000 RSI: 00007fff016ec950 RDI: 000000000000000c
RBP: 00007fff016f0b70 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 000055f1f719fc60
R13: 000000000000000c R14: 00007fff016f0b30 R15: 00007fff016f0b70
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/18 21:39 linux-5.15.y b9d57c40a767 303e2802 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in __netlink_dump_start
* Struck through repros no longer work on HEAD.