Message-ID: <692e18e0.a70a0220.d98e3.018f.GAE@google.com>
Date: Mon, 01 Dec 2025 14:38:24 -0800
From: syzbot <syzbot+31dce4175fcaed9dae98@...kaller.appspotmail.com>
To: Dai.Ngo@...cle.com, chuck.lever@...cle.com, jlayton@...nel.org, 
	linux-kernel@...r.kernel.org, linux-nfs@...r.kernel.org, neil@...wn.name, 
	okorniev@...hat.com, syzkaller-bugs@...glegroups.com, tom@...pey.com
Subject: [syzbot] [nfs?] INFO: task hung in nfsd_nl_version_set_doit (2)

Hello,

syzbot found the following issue on:

HEAD commit:    7d0a66e4bb90 Linux 6.18
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13d52512580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=1cd7f786c0f5182f
dashboard link: https://syzkaller.appspot.com/bug?extid=31dce4175fcaed9dae98
compiler:       gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/426e88dc4200/disk-7d0a66e4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/07f64a43f087/vmlinux-7d0a66e4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/43778a8316e2/bzImage-7d0a66e4.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+31dce4175fcaed9dae98@...kaller.appspotmail.com

INFO: task syz.7.3138:20679 blocked for more than 143 seconds.
      Tainted: G          I         syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.7.3138      state:D stack:27528 pid:20679 tgid:20678 ppid:19956  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5325 [inline]
 __schedule+0x1190/0x5de0 kernel/sched/core.c:6929
 __schedule_loop kernel/sched/core.c:7011 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:7026
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7083
 __mutex_lock_common kernel/locking/mutex.c:676 [inline]
 __mutex_lock+0x818/0x1060 kernel/locking/mutex.c:760
 nfsd_nl_version_set_doit+0xc4/0x7a0 fs/nfsd/nfsctl.c:1730
 genl_family_rcv_msg_doit+0x209/0x2f0 net/netlink/genetlink.c:1115
 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
 genl_rcv_msg+0x55c/0x800 net/netlink/genetlink.c:1210
 netlink_rcv_skb+0x158/0x420 net/netlink/af_netlink.c:2552
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8c8/0xdd0 net/netlink/af_netlink.c:1896
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg net/socket.c:742 [inline]
 ____sys_sendmsg+0xa98/0xc70 net/socket.c:2630
 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2684
 __sys_sendmsg+0x16d/0x220 net/socket.c:2716
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff6b358f7c9
RSP: 002b:00007ff6b43f7038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007ff6b37e5fa0 RCX: 00007ff6b358f7c9
RDX: 0000000004004000 RSI: 0000200000003200 RDI: 0000000000000003
RBP: 00007ff6b3613f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff6b37e6038 R14: 00007ff6b37e5fa0 R15: 00007fffed6dad48
 </TASK>
INFO: task syz.6.3144:20706 blocked for more than 147 seconds.
      Tainted: G          I         syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.3144      state:D stack:27448 pid:20706 tgid:20705 ppid:19445  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5325 [inline]
 __schedule+0x1190/0x5de0 kernel/sched/core.c:6929
 __schedule_loop kernel/sched/core.c:7011 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:7026
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7083
 __mutex_lock_common kernel/locking/mutex.c:676 [inline]
 __mutex_lock+0x818/0x1060 kernel/locking/mutex.c:760
 nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:593
 nfsd_umount+0x48/0xe0 fs/nfsd/nfsctl.c:1347
 deactivate_locked_super+0xc1/0x1a0 fs/super.c:473
 deactivate_super fs/super.c:506 [inline]
 deactivate_super+0xde/0x100 fs/super.c:502
 cleanup_mnt+0x225/0x450 fs/namespace.c:1318
 task_work_run+0x150/0x240 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xec/0x130 kernel/entry/common.c:43
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x426/0xfa0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f70f958f7c9
RSP: 002b:00007f70fa3f9038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: fffffffffffffffe RBX: 00007f70f97e5fa0 RCX: 00007f70f958f7c9
RDX: 0000200000000100 RSI: 00002000000000c0 RDI: 0000000000000000
RBP: 00007f70f9613f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f70f97e6038 R14: 00007f70f97e5fa0 R15: 00007ffd32d60018
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8e3c45e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e3c45e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
 #0: ffffffff8e3c45e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6775
2 locks held by kworker/1:4/5890:
 #0: ffff88813ff15948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3238
 #1: ffffc9000456fd00 (free_ipc_work){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3239
2 locks held by kworker/u10:4/13138:
 #0: ffff88813ff29148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3238
 #1: ffff8880b8524088 (psi_seq){-.-.}-{0:0}, at: psi_sched_switch kernel/sched/stats.h:220 [inline]
 #1: ffff8880b8524088 (psi_seq){-.-.}-{0:0}, at: __schedule+0x1861/0x5de0 kernel/sched/core.c:6923
2 locks held by syz.4.1989/15528:
 #0: ffff88806018e0e0 (&type->s_umount_key#52){++++}-{4:4}, at: __super_lock fs/super.c:57 [inline]
 #0: ffff88806018e0e0 (&type->s_umount_key#52){++++}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
 #0: ffff88806018e0e0 (&type->s_umount_key#52){++++}-{4:4}, at: deactivate_super fs/super.c:505 [inline]
 #0: ffff88806018e0e0 (&type->s_umount_key#52){++++}-{4:4}, at: deactivate_super+0xd6/0x100 fs/super.c:502
 #1: ffffffff8e7ed348 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:593
5 locks held by kworker/u10:10/18292:
 #0: ffff88801ba9f148 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3238
 #1: ffffc90004a9fd00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3239
 #2: ffffffff900d52b0 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xad/0x8b0 net/core/net_namespace.c:669
 #3: ffffffff900eb6c8 (rtnl_mutex){+.+.}-{4:4}, at: wiphy_unregister+0x13d/0xc50 net/wireless/core.c:1165
 #4: ffff88805dad0788 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: wiphy_lock include/net/cfg80211.h:6343 [inline]
 #4: ffff88805dad0788 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: wiphy_unregister+0x147/0xc50 net/wireless/core.c:1166
3 locks held by kworker/u10:12/18294:
 #0: ffff888030d69948 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3238
 #1: ffffc90003eefd00 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3239
 #2: ffffffff900eb6c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #2: ffffffff900eb6c8 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_verify_work+0x12/0x30 net/ipv6/addrconf.c:4734
1 lock held by syz.1.2823/19276:
2 locks held by syz.5.2942/19853:
 #0: ffffffff9018f490 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8e7ed348 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x687/0xbc0 fs/nfsd/nfsctl.c:1590
2 locks held by getty/20629:
 #0: ffff88803528d0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc90002fd22f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x41b/0x14f0 drivers/tty/n_tty.c:2222
2 locks held by syz.7.3138/20679:
 #0: ffffffff9018f490 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8e7ed348 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_version_set_doit+0xc4/0x7a0 fs/nfsd/nfsctl.c:1730
2 locks held by syz.6.3144/20706:
 #0: ffff88805a2600e0 (&type->s_umount_key#52){++++}-{4:4}, at: __super_lock fs/super.c:57 [inline]
 #0: ffff88805a2600e0 (&type->s_umount_key#52){++++}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
 #0: ffff88805a2600e0 (&type->s_umount_key#52){++++}-{4:4}, at: deactivate_super fs/super.c:505 [inline]
 #0: ffff88805a2600e0 (&type->s_umount_key#52){++++}-{4:4}, at: deactivate_super+0xd6/0x100 fs/super.c:502
 #1: ffffffff8e7ed348 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:593
2 locks held by syz-executor/20776:
 #0: ffff88805b41e0e0 (&type->s_umount_key#52){++++}-{4:4}, at: __super_lock fs/super.c:57 [inline]
 #0: ffff88805b41e0e0 (&type->s_umount_key#52){++++}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
 #0: ffff88805b41e0e0 (&type->s_umount_key#52){++++}-{4:4}, at: deactivate_super fs/super.c:505 [inline]
 #0: ffff88805b41e0e0 (&type->s_umount_key#52){++++}-{4:4}, at: deactivate_super+0xd6/0x100 fs/super.c:502
 #1: ffffffff8e7ed348 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:593
2 locks held by syz.2.3203/21060:
 #0: ffff88801c3480e0 (&type->s_umount_key#52){++++}-{4:4}, at: __super_lock fs/super.c:57 [inline]
 #0: ffff88801c3480e0 (&type->s_umount_key#52){++++}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
 #0: ffff88801c3480e0 (&type->s_umount_key#52){++++}-{4:4}, at: deactivate_super fs/super.c:505 [inline]
 #0: ffff88801c3480e0 (&type->s_umount_key#52){++++}-{4:4}, at: deactivate_super+0xd6/0x100 fs/super.c:502
 #1: ffffffff8e7ed348 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:593
2 locks held by syz.3.3291/21497:
 #0: ffff8880753ce0e0 (&type->s_umount_key#52){++++}-{4:4}, at: __super_lock fs/super.c:57 [inline]
 #0: ffff8880753ce0e0 (&type->s_umount_key#52){++++}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
 #0: ffff8880753ce0e0 (&type->s_umount_key#52){++++}-{4:4}, at: deactivate_super fs/super.c:505 [inline]
 #0: ffff8880753ce0e0 (&type->s_umount_key#52){++++}-{4:4}, at: deactivate_super+0xd6/0x100 fs/super.c:502
 #1: ffffffff8e7ed348 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:593
2 locks held by syz-executor/21510:
 #0: ffffffff8f492c00 (&ops->srcu#2){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:161 [inline]
 #0: ffffffff8f492c00 (&ops->srcu#2){.+.+}-{0:0}, at: srcu_read_lock include/linux/srcu.h:253 [inline]
 #0: ffffffff8f492c00 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x113/0x2c0 net/core/rtnetlink.c:574
 #1: ffffffff900eb6c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #1: ffffffff900eb6c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #1: ffffffff900eb6c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x600/0x2000 net/core/rtnetlink.c:4064
1 lock held by syz.9.3298/21533:
 #0: ffffffff8e3cfb78 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x1a3/0x3c0 kernel/rcu/tree_exp.h:343
5 locks held by syz.8.3302/21552:
 #0: ffff8880334d0dc8 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close+0x26/0x90 net/bluetooth/hci_core.c:499


---
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