INFO: task syz.4.2455:15926 blocked for more than 143 seconds. Not tainted 6.14.0-rc4-syzkaller-00248-g03d38806a902 #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.4.2455 state:D stack:27264 pid:15926 tgid:15924 ppid:14866 task_flags:0x400140 flags:0x00000004 Call Trace: context_switch kernel/sched/core.c:5378 [inline] __schedule+0xf43/0x5890 kernel/sched/core.c:6765 __schedule_loop kernel/sched/core.c:6842 [inline] schedule+0xe7/0x350 kernel/sched/core.c:6857 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6914 __mutex_lock_common kernel/locking/mutex.c:662 [inline] __mutex_lock+0x6bd/0xb10 kernel/locking/mutex.c:730 nfsd_nl_threads_set_doit+0x694/0xbe0 fs/nfsd/nfsctl.c:1629 genl_family_rcv_msg_doit+0x202/0x2f0 net/netlink/genetlink.c:1115 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] genl_rcv_msg+0x565/0x800 net/netlink/genetlink.c:1210 netlink_rcv_skb+0x16b/0x440 net/netlink/af_netlink.c:2533 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline] netlink_unicast+0x53c/0x7f0 net/netlink/af_netlink.c:1338 netlink_sendmsg+0x8b8/0xd70 net/netlink/af_netlink.c:1882 sock_sendmsg_nosec net/socket.c:718 [inline] __sock_sendmsg net/socket.c:733 [inline] ____sys_sendmsg+0xaaf/0xc90 net/socket.c:2573 ___sys_sendmsg+0x135/0x1e0 net/socket.c:2627 __sys_sendmsg+0x16e/0x220 net/socket.c:2659 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f7a6bb8d169 RSP: 002b:00007f7a6caa2038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f7a6bda5fa0 RCX: 00007f7a6bb8d169 RDX: 0000000000000840 RSI: 0000400000000240 RDI: 0000000000000003 RBP: 00007f7a6bc0e2a0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f7a6bda5fa0 R15: 00007ffd3d86b108 Showing all locks held in the system: 1 lock held by khungtaskd/30: #0: ffffffff8e1bccc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline] #0: ffffffff8e1bccc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffffffff8e1bccc0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x7f/0x390 kernel/locking/lockdep.c:6746 2 locks held by kworker/u8:9/2989: 3 locks held by kworker/u8:15/9693: #0: ffff88814d242148 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x1293/0x1ba0 kernel/workqueue.c:3213 #1: ffffc900032e7d18 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work+0x921/0x1ba0 kernel/workqueue.c:3214 #2: ffffffff8fef9368 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:129 [inline] #2: ffffffff8fef9368 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_dad_work+0x121/0x14e0 net/ipv6/addrconf.c:4190 2 locks held by kworker/u8:16/9695: 3 locks held by kworker/0:8/13355: 2 locks held by syz-executor/15011: #0: ffff88806c2240e0 (&type->s_umount_key#50){++++}-{4:4}, at: __super_lock fs/super.c:56 [inline] #0: ffff88806c2240e0 (&type->s_umount_key#50){++++}-{4:4}, at: __super_lock_excl fs/super.c:71 [inline] #0: ffff88806c2240e0 (&type->s_umount_key#50){++++}-{4:4}, at: deactivate_super+0xd6/0x100 fs/super.c:505 #1: ffffffff8e5bfe68 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:596 2 locks held by getty/15503: #0: ffff8880357320a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243 #1: ffffc9000410b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0xfba/0x1480 drivers/tty/n_tty.c:2211 2 locks held by syz.2.2431/15775: #0: ffffffff8ff9a0f0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218 #1: ffffffff8e5bfe68 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0xe3/0x1b40 fs/nfsd/nfsctl.c:1922 2 locks held by syz.4.2455/15926: #0: ffffffff8ff9a0f0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218 #1: ffffffff8e5bfe68 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x694/0xbe0 fs/nfsd/nfsctl.c:1629 2 locks held by syz-executor/16056: #0: ffff888032c0a0e0 (&type->s_umount_key#50){++++}-{4:4}, at: __super_lock fs/super.c:56 [inline] #0: ffff888032c0a0e0 (&type->s_umount_key#50){++++}-{4:4}, at: __super_lock_excl fs/super.c:71 [inline] #0: ffff888032c0a0e0 (&type->s_umount_key#50){++++}-{4:4}, at: deactivate_super+0xd6/0x100 fs/super.c:505 #1: ffffffff8e5bfe68 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:596 2 locks held by syz-executor/16212: #0: ffff88806050a0e0 (&type->s_umount_key#50){++++}-{4:4}, at: __super_lock fs/super.c:56 [inline] #0: ffff88806050a0e0 (&type->s_umount_key#50){++++}-{4:4}, at: __super_lock_excl fs/super.c:71 [inline] #0: ffff88806050a0e0 (&type->s_umount_key#50){++++}-{4:4}, at: deactivate_super+0xd6/0x100 fs/super.c:505 #1: ffffffff8e5bfe68 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:596 1 lock held by syz.9.2645/17277: #0: ffffffff8ee89ce8 (tty_mutex){+.+.}-{4:4}, at: tty_release_struct+0xad/0xe0 drivers/tty/tty_io.c:1700 6 locks held by syz.9.2652/17374: 2 locks held by syz.3.2656/17437: #0: ffffffff8ee89ce8 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2046 [inline] #0: ffffffff8ee89ce8 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf80 drivers/tty/tty_io.c:2129 #1: ffff888087a8d1c0 (&tty->legacy_mutex){+.+.}-{4:4}, at: tty_init_dev.part.0+0x37/0x660 drivers/tty/tty_io.c:1415 1 lock held by syz.0.2667/17549: #0: ffffffff8ee89ce8 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2046 [inline] #0: ffffffff8ee89ce8 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf80 drivers/tty/tty_io.c:2129 1 lock held by syz.5.2677/17667: #0: ffffffff8ee89ce8 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2046 [inline] #0: ffffffff8ee89ce8 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf80 drivers/tty/tty_io.c:2129 2 locks held by syz.6.2670/17742: #0: ffffffff8ff9a0f0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218 #1: ffffffff8e5bfe68 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x694/0xbe0 fs/nfsd/nfsctl.c:1629 1 lock held by syz.2.2681/17815: #0: ffffffff8ee89ce8 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2046 [inline] #0: ffffffff8ee89ce8 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf80 drivers/tty/tty_io.c:2129 1 lock held by syz.2.2681/17818: #0: ffffffff8ee89ce8 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2046 [inline] #0: ffffffff8ee89ce8 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf80 drivers/tty/tty_io.c:2129 1 lock held by syz.4.2682/17832: #0: ffffffff8ee89ce8 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2046 [inline] #0: ffffffff8ee89ce8 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf80 drivers/tty/tty_io.c:2129 1 lock held by syz.4.2682/17833: #0: ffffffff8ee89ce8 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2046 [inline] #0: ffffffff8ee89ce8 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53d/0xf80 drivers/tty/tty_io.c:2129 1 lock held by syz.1.2685/17947: #0: ffffffff8ee89ce8 (tty_mutex){+.+.}-{4:4}, at: ptmx_open drivers/tty/pty.c:823 [inline] #0: ffffffff8ee89ce8 (tty_mutex){+.+.}-{4:4}, at: ptmx_open+0xff/0x360 drivers/tty/pty.c:790 4 locks held by syz-executor/17974: 1 lock held by syz-executor/18056: 7 locks held by syz-executor/18086: #0: ffff888030c4e420 (sb_writers#8){.+.+}-{0:0}, at: ksys_write+0x12b/0x250 fs/read_write.c:731 #1: ffff88809bf61088 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x27b/0x500 fs/kernfs/file.c:325 #2: ffff88802817a788 (kn->active#49){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x29e/0x500 fs/kernfs/file.c:326 #3: ffffffff8f4a3f28 (nsim_bus_dev_list_lock){+.+.}-{4:4}, at: del_device_store+0xd2/0x4b0 drivers/net/netdevsim/bus.c:216 #4: ffff8880732b30e8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1030 [inline] #4: ffff8880732b30e8 (&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1095 [inline] #4: ffff8880732b30e8 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xa4/0x610 drivers/base/dd.c:1293 #5: ffff8880732b4250 (&devlink->lock_key#29){+.+.}-{4:4}, at: nsim_drv_remove+0x4a/0x1d0 drivers/net/netdevsim/dev.c:1675 #6: ffffffff8e1c8000 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x48/0x700 kernel/rcu/tree.c:3741 4 locks held by rm/18166: ============================================= NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 30 Comm: khungtaskd Not tainted 6.14.0-rc4-syzkaller-00248-g03d38806a902 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 nmi_cpu_backtrace+0x27b/0x390 lib/nmi_backtrace.c:113 nmi_trigger_cpumask_backtrace+0x29c/0x300 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:236 [inline] watchdog+0xf62/0x12b0 kernel/hung_task.c:399 kthread+0x3af/0x750 kernel/kthread.c:464 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244