INFO: task syz.4.7983:30335 blocked for more than 143 seconds. Tainted: G I 6.16.0-rc2-syzkaller-00162-g41687a5c6f8b #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.4.7983 state:D stack:28376 pid:30335 tgid:30330 ppid:13776 task_flags:0x400140 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:5396 [inline] __schedule+0x116a/0x5de0 kernel/sched/core.c:6785 __schedule_loop kernel/sched/core.c:6863 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:6878 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6935 __mutex_lock_common kernel/locking/mutex.c:679 [inline] __mutex_lock+0x6c7/0xb90 kernel/locking/mutex.c:747 nfsd_nl_threads_set_doit+0x698/0xbf0 fs/nfsd/nfsctl.c:1629 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:2534 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline] netlink_unicast+0x53a/0x7f0 net/netlink/af_netlink.c:1339 netlink_sendmsg+0x8d1/0xdd0 net/netlink/af_netlink.c:1883 sock_sendmsg_nosec net/socket.c:712 [inline] __sock_sendmsg net/socket.c:727 [inline] ____sys_sendmsg+0xa98/0xc70 net/socket.c:2566 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2620 __sys_sendmsg+0x16d/0x220 net/socket.c:2652 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x490 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f526558e929 RSP: 002b:00007f52633d5038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f52657b6080 RCX: 00007f526558e929 RDX: 0000000000000050 RSI: 0000200000000480 RDI: 0000000000000002 RBP: 00007f5265610b39 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f52657b6080 R15: 00007ffe609bd9a8 Showing all locks held in the system: 2 locks held by kworker/u8:0/12: #0: ffff888021b50948 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3213 #1: ffffc90000117d10 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3214 1 lock held by khungtaskd/31: #0: ffffffff8e5c4700 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #0: ffffffff8e5c4700 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #0: ffffffff8e5c4700 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6770 3 locks held by kworker/0:3/1228: #0: ffff88801b880d48 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3213 #1: ffffc90003f4fd10 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3214 #2: ffff8880603a7240 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x1bb/0x2e80 drivers/net/netdevsim/fib.c:1490 2 locks held by kworker/u8:6/1347: 3 locks held by kworker/u8:8/3522: 6 locks held by kworker/u8:9/3546: 2 locks held by getty/24437: #0: ffff888031f3c0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243 #1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x41b/0x14f0 drivers/tty/n_tty.c:2222 2 locks held by syz.3.7940/30180: #0: ffffffff903f3170 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218 #1: ffffffff8e9ddc28 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x698/0xbf0 fs/nfsd/nfsctl.c:1629 2 locks held by syz.4.7983/30335: #0: ffffffff903f3170 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218 #1: ffffffff8e9ddc28 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x698/0xbf0 fs/nfsd/nfsctl.c:1629 6 locks held by syz.7.8072/30756: 2 locks held by syz.6.8125/30996: #0: ffffffff8f2c8b68 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f2c8b68 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53e/0xf90 drivers/tty/tty_io.c:2120 #1: ffff8880787a51c0 (&tty->legacy_mutex){+.+.}-{4:4}, at: tty_init_dev.part.0+0x37/0x500 drivers/tty/tty_io.c:1406 1 lock held by syz.8.8130/31027: #0: ffffffff8f2c8b68 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f2c8b68 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53e/0xf90 drivers/tty/tty_io.c:2120 1 lock held by syz.8.8130/31028: #0: ffffffff8f2c8b68 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f2c8b68 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53e/0xf90 drivers/tty/tty_io.c:2120 2 locks held by syz.0.8139/31073: #0: ffffffff903f3170 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218 #1: ffffffff8e9ddc28 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x698/0xbf0 fs/nfsd/nfsctl.c:1629 3 locks held by syz.1.8172/31322: #0: ffff8880365ba428 (sb_writers#7){.+.+}-{0:0}, at: splice_direct_to_actor+0x342/0xa30 fs/splice.c:1102 #1: ffff888044af3888 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x28f/0x510 fs/kernfs/file.c:325 #2: ffff888142334788 (kn->active#112){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x2b2/0x510 fs/kernfs/file.c:326 1 lock held by syz.3.8192/31768: #0: ffffffff8f2c8b68 (tty_mutex){+.+.}-{4:4}, at: ptmx_open drivers/tty/pty.c:823 [inline] #0: ffffffff8f2c8b68 (tty_mutex){+.+.}-{4:4}, at: ptmx_open+0xff/0x360 drivers/tty/pty.c:790 1 lock held by syz.3.8192/31770: #0: ffffffff8f2c8b68 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f2c8b68 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53e/0xf90 drivers/tty/tty_io.c:2120 1 lock held by syz.9.8235/31899: #0: ffffffff8f2c8b68 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f2c8b68 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53e/0xf90 drivers/tty/tty_io.c:2120 1 lock held by syz.9.8235/31901: #0: ffffffff8f2c8b68 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f2c8b68 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53e/0xf90 drivers/tty/tty_io.c:2120 1 lock held by syz.2.8238/31939: #0: ffffffff8f2c8b68 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline] #0: ffffffff8f2c8b68 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53e/0xf90 drivers/tty/tty_io.c:2120 1 lock held by syz-executor/31952: 2 locks held by syz.5.8241/31987: ============================================= NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Tainted: G I 6.16.0-rc2-syzkaller-00162-g41687a5c6f8b #0 PREEMPT(full) Tainted: [I]=FIRMWARE_WORKAROUND Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 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:158 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:307 [inline] watchdog+0xf70/0x12c0 kernel/hung_task.c:470 kthread+0x3c5/0x780 kernel/kthread.c:464 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245