syzbot


INFO: task hung in nfsd_umount

Status: upstream: reported on 2024/07/07 04:37
Subsystems: nfs
[Documentation on labels]
Reported-by: syzbot+b568ba42c85a332a88ee@syzkaller.appspotmail.com
First crash: 687d, last: 16m
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
a607d1e4-f56a-479f-bd5d-819025c7ef3e repro INFO: task hung in nfsd_umount 2026/03/07 03:10 2026/03/07 03:11 2026/03/07 03:20 31e9c887f7dc24e04b3ca70d0d54fc34141844b0
Discussions (3)
Title Replies (including bot) Last reply
[syzbot] Monthly nfs report (Jul 2025) 0 (1) 2025/07/04 12:38
[syzbot] Monthly nfs report (Jun 2025) 0 (1) 2025/06/03 09:38
[syzbot] [nfs?] INFO: task hung in nfsd_umount 3 (4) 2024/09/21 07:58

Sample crash report:
INFO: task syz-executor:23824 blocked for more than 143 seconds.
      Tainted: G     U       L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:24232 pid:23824 tgid:23824 ppid:1      task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5298 [inline]
 __schedule+0xfee/0x6120 kernel/sched/core.c:6911
 __schedule_loop kernel/sched/core.c:6993 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:7008
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7065
 __mutex_lock_common kernel/locking/mutex.c:692 [inline]
 __mutex_lock+0xc9a/0x1b90 kernel/locking/mutex.c:776
 nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
 nfsd_umount+0x3b/0x60 fs/nfsd/nfsctl.c:1364
 deactivate_locked_super+0xc1/0x1b0 fs/super.c:476
 deactivate_super fs/super.c:509 [inline]
 deactivate_super+0xe7/0x110 fs/super.c:505
 cleanup_mnt+0x21f/0x450 fs/namespace.c:1312
 task_work_run+0x150/0x240 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
 exit_to_user_mode_loop+0x100/0x4a0 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
 do_syscall_64+0x668/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8119d9da57
RSP: 002b:00007fffa408cdd8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f8119e32048 RCX: 00007f8119d9da57
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fffa408ce90
RBP: 00007fffa408ce90 R08: 00007fffa408de90 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fffa408df20
R13: 00007f8119e32048 R14: 00000000001a3f55 R15: 00007fffa408df60
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/30:
 #0: ffffffff8e7e7760 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #0: ffffffff8e7e7760 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #0: ffffffff8e7e7760 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775
3 locks held by kworker/0:7/11727:
5 locks held by kworker/u10:14/17661:
 #0: ffff88801c6b6948 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x1310/0x19a0 kernel/workqueue.c:3251
 #1: ffffc900033afd08 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x988/0x19a0 kernel/workqueue.c:3252
 #2: ffffffff905fe850 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xb8/0x920 net/core/net_namespace.c:675
 #3: ffffffff906170a8 (rtnl_mutex){+.+.}-{4:4}, at: ops_exit_rtnl_list net/core/net_namespace.c:173 [inline]
 #3: ffffffff906170a8 (rtnl_mutex){+.+.}-{4:4}, at: ops_undo_list+0x7ec/0xab0 net/core/net_namespace.c:248
 #4: ffffffff8e7f32b8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x27f/0x3c0 kernel/rcu/tree_exp.h:311
2 locks held by syz-executor/23824:
 #0: ffff888035a060e0 (&type->s_umount_key#53){++++}-{4:4}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff888035a060e0 (&type->s_umount_key#53){++++}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
 #0: ffff888035a060e0 (&type->s_umount_key#53){++++}-{4:4}, at: deactivate_super fs/super.c:508 [inline]
 #0: ffff888035a060e0 (&type->s_umount_key#53){++++}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:505
 #1: ffffffff8ec58e28 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
2 locks held by syz.3.3842/25151:
 #0: ffffffff906c33f0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
 #1: ffffffff8ec58e28 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x6c1/0xc00 fs/nfsd/nfsctl.c:1607
3 locks held by syz.9.4016/25945:
 #0: ffffffff906c33f0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
 #1: ffff88805c1c16f0 (nlk_cb_mutex-GENERIC){+.+.}-{4:4}, at: __netlink_dump_start+0x150/0x990 net/netlink/af_netlink.c:2404
 #2: ffffffff8ec58e28 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_rpc_status_get_dumpit+0xb7/0x1200 fs/nfsd/nfsctl.c:1494
2 locks held by syz.8.4021/25968:
 #0: ffffffff906c33f0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
 #1: ffffffff8ec58e28 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_version_set_doit+0xc4/0x7a0 fs/nfsd/nfsctl.c:1753
2 locks held by syz-executor/26140:
 #0: ffff88802b4f40e0 (&type->s_umount_key#53){++++}-{4:4}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88802b4f40e0 (&type->s_umount_key#53){++++}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
 #0: ffff88802b4f40e0 (&type->s_umount_key#53){++++}-{4:4}, at: deactivate_super fs/super.c:508 [inline]
 #0: ffff88802b4f40e0 (&type->s_umount_key#53){++++}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:505
 #1: ffffffff8ec58e28 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
2 locks held by syz.2.4143/26661:
 #0: ffffffff906c33f0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
 #1: ffffffff8ec58e28 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x6c1/0xc00 fs/nfsd/nfsctl.c:1607
2 locks held by syz.4.4148/26693:
 #0: ffffffff906c33f0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
 #1: ffffffff8ec58e28 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x6c1/0xc00 fs/nfsd/nfsctl.c:1607
1 lock held by syz-executor/26885:
 #0: ffffffff8e7f32b8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x19e/0x3c0 kernel/rcu/tree_exp.h:343
4 locks held by dhcpcd-run-hook/27513:

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 30 Comm: khungtaskd Tainted: G     U       L      syzkaller #0 PREEMPT(full) 
Tainted: [U]=USER, [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 nmi_cpu_backtrace.cold+0x12d/0x151 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x1d7/0x230 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+0x141/0x190 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline]
 watchdog+0xd25/0x1050 kernel/hung_task.c:515
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Crashes (3956):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/07 06:55 upstream bfe62a454542 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/04/07 02:50 upstream bfe62a454542 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/04/07 00:53 upstream bfe62a454542 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/04/06 14:16 upstream 591cd656a1bf 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/04/06 08:28 upstream 591cd656a1bf 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/04/06 06:01 upstream 1791c390149f 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/04/06 03:39 upstream 1791c390149f 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/04/06 01:55 upstream 1791c390149f 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/04/05 14:35 upstream 3aae9383f42f 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/04/04 20:15 upstream 7ca6d1cfec80 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/04/04 16:38 upstream 7ca6d1cfec80 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in nfsd_umount
2026/04/04 14:04 upstream 7ca6d1cfec80 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/04/04 13:00 upstream 631919fb12fe 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/04/04 05:34 upstream 631919fb12fe 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/04/03 18:05 upstream d8a9a4b11a13 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/04/03 16:37 upstream d8a9a4b11a13 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/04/03 15:25 upstream d8a9a4b11a13 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/04/03 10:14 upstream 5619b098e2fb 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/04/03 08:21 upstream 5619b098e2fb 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/04/03 02:17 upstream 5619b098e2fb 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/04/02 16:31 upstream 9147566d8016 91bc79b0 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/04/02 14:18 upstream 9147566d8016 8b15d4ae .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in nfsd_umount
2026/04/02 12:53 upstream 9147566d8016 0cb124d5 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in nfsd_umount
2026/04/02 08:39 upstream 9147566d8016 0cb124d5 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/04/02 06:57 upstream 9147566d8016 0cb124d5 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/04/02 04:59 upstream 9147566d8016 0cb124d5 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/04/02 04:12 upstream 9147566d8016 0cb124d5 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/04/02 02:22 upstream 9147566d8016 0cb124d5 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/04/01 21:19 upstream 9147566d8016 0cb124d5 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/04/01 04:40 upstream d0c3bcd5b897 ef441708 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/03/28 12:52 upstream 7df48e363130 ef441708 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/03/28 10:31 upstream 7df48e363130 ef441708 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/03/28 06:13 upstream 7df48e363130 ef441708 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/03/28 02:23 upstream 7df48e363130 ef441708 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/03/27 22:42 upstream 7df48e363130 ef441708 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/03/27 10:27 upstream 46b513250491 4b3d9a38 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/03/27 08:31 upstream 46b513250491 4b3d9a38 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/03/27 00:49 upstream 0138af2472df 4b3d9a38 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/03/26 09:38 upstream d2a43e7f89da c6143aac .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/03/26 07:53 upstream d2a43e7f89da c6143aac .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/03/26 05:10 upstream d2a43e7f89da c6143aac .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/03/26 00:57 upstream d2a43e7f89da c6143aac .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/03/25 23:17 upstream bbeb83d3182a 4367a094 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/03/25 22:08 upstream bbeb83d3182a 4367a094 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/03/25 19:22 upstream bbeb83d3182a 4367a094 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/03/25 10:40 upstream 24f9515de877 b4723e5f .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/03/25 09:32 upstream 24f9515de877 b4723e5f .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/03/25 07:30 upstream 24f9515de877 b4723e5f .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/03/24 23:24 upstream e3c33bc767b5 74e70d19 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/03/24 21:52 upstream e3c33bc767b5 74e70d19 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2026/03/14 17:38 upstream 1c9982b49613 ee8d34d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in nfsd_umount
2026/03/06 23:37 upstream 651690480a96 5cb44a80 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in nfsd_umount
2024/07/06 12:12 upstream 1dd28064d416 bc4ebbb5 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in nfsd_umount
2024/07/03 04:33 upstream e9d22f7a6655 1ecfa2d8 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in nfsd_umount
2024/06/29 05:25 upstream 6c0483dbfe72 757f06b1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in nfsd_umount
2026/03/29 20:31 linux-next 3b058d1aeeef 356bdfc9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in nfsd_umount
2026/03/29 05:26 linux-next 3b058d1aeeef 356bdfc9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: task hung in nfsd_umount
2026/03/28 00:20 linux-next e77a5a5cfe43 74a13a23 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in nfsd_umount
2026/03/24 14:27 linux-next 09c0f7f1bcdb 74e70d19 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in nfsd_umount
* Struck through repros no longer work on HEAD.