INFO: task syz.0.1144:10201 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.0.1144 state:D stack:26656 pid:10201 tgid:10200 ppid:5609 task_flags:0x400140 flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5535 [inline] __schedule+0x1b47/0x5c60 kernel/sched/core.c:7305 __schedule_loop kernel/sched/core.c:7382 [inline] schedule+0x164/0x2b0 kernel/sched/core.c:7397 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7454 __mutex_lock_common kernel/locking/mutex.c:726 [inline] __mutex_lock+0x7c4/0x15a0 kernel/locking/mutex.c:821 nfsd_nl_unlock_export_doit+0x2ef/0x580 fs/nfsd/nfsctl.c:2746 genl_family_rcv_msg_doit+0x233/0x340 net/netlink/genetlink.c:1114 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline] genl_rcv_msg+0x614/0x7a0 net/netlink/genetlink.c:1209 netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2572 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218 netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline] netlink_unicast+0x7bd/0x940 net/netlink/af_netlink.c:1361 netlink_sendmsg+0x7c3/0xae0 net/netlink/af_netlink.c:1916 sock_sendmsg_nosec+0x13a/0x180 net/socket.c:800 __sock_sendmsg net/socket.c:815 [inline] ____sys_sendmsg+0x54e/0x850 net/socket.c:2712 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2766 __sys_sendmsg net/socket.c:2798 [inline] __do_sys_sendmsg net/socket.c:2803 [inline] __se_sys_sendmsg net/socket.c:2801 [inline] __x64_sys_sendmsg+0x1b1/0x290 net/socket.c:2801 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f35c159e159 RSP: 002b:00007f35c24cc028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f35c1825fa0 RCX: 00007f35c159e159 RDX: 0000000004000080 RSI: 0000200000000100 RDI: 0000000000000004 RBP: 00007f35c163506b R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f35c1826038 R14: 00007f35c1825fa0 R15: 00007ffdc9b97488 Showing all locks held in the system: locks held by khungtaskd/33: 1, last CPU#0: #0: ffffffff8f15c2a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffffffff8f15c2a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffffffff8f15c2a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6871 locks held by kworker/u8:7/1098: 5, last CPU#0: #0: ffff88801c286148 ((wq_completion)netns){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffff88801c286148 ((wq_completion)netns){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffff88801c286148 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline] #0: ffff88801c286148 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578 #1: ffffc90005147c40 (net_cleanup_work){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #1: ffffc90005147c40 (net_cleanup_work){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffc90005147c40 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline] #1: ffffc90005147c40 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578 #2: ffffffff90666468 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf5/0x810 net/core/net_namespace.c:677 #3: ffffffff90674ce0 (rtnl_mutex){+.+.}-{4:4}, at: ops_exit_rtnl_list net/core/net_namespace.c:173 [inline] #3: ffffffff90674ce0 (rtnl_mutex){+.+.}-{4:4}, at: ops_undo_list+0x28e/0x8f0 net/core/net_namespace.c:249 #4: ffffffff8f15c2a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #4: ffffffff8f15c2a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #4: ffffffff8f15c2a0 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1216 [inline] #4: ffffffff8f15c2a0 (rcu_read_lock){....}-{1:3}, at: kernfs_root+0x1c/0x230 fs/kernfs/kernfs-internal.h:76 locks held by kworker/0:4/1907: 6, on CPU#0: #0: ffff88801eeee948 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffff88801eeee948 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffff88801eeee948 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline] #0: ffff88801eeee948 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578 #1: ffffc90006357c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #1: ffffc90006357c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffc90006357c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline] #1: ffffc90006357c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578 #2: ffff888029e931d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline] #2: ffff888029e931d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4d30 drivers/usb/core/hub.c:5917 #3: ffff88807b3b31d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline] #3: ffff88807b3b31d8 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x450 drivers/base/dd.c:1073 #4: ffff8880555571a0 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline] #4: ffff8880555571a0 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x450 drivers/base/dd.c:1073 #5: ffffffff8eff6288 (umhelper_sem){++++}-{4:4}, at: usermodehelper_read_trylock+0xfc/0x2b0 kernel/umh.c:212 locks held by getty/5365: 2, on CPU#0: #0: ffff88801c7760a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243 #1: ffffc900032332e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360 drivers/tty/n_tty.c:2211 locks held by syz.3.996/9677: 3, on CPU#0: #0: ffff88807f7089b0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x118/0x160 fs/file.c:1408 #1: ffff88807ee5a460 (sb_writers#25){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2753 [inline] #1: ffff88807ee5a460 (sb_writers#25){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0 fs/read_write.c:683 #2: ffffffff8f49f8e0 (nfsd_mutex){+.+.}-{4:4}, at: write_ports+0xb5/0xd10 fs/nfsd/nfsctl.c:874 locks held by syz.0.1144/10201: 2, on CPU#0: #0: ffffffff906e5fc8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217 #1: ffffffff8f49f8e0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_unlock_export_doit+0x2ef/0x580 fs/nfsd/nfsctl.c:2746 locks held by kworker/u8:15/13098: 3, last CPU#0: #0: ffff88813fe4c148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffff88813fe4c148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffff88813fe4c148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline] #0: ffff88813fe4c148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578 #1: ffffc90005747c40 ((work_completion)(&(&nsim_dev->trap_data->trap_report_dw)->work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #1: ffffc90005747c40 ((work_completion)(&(&nsim_dev->trap_data->trap_report_dw)->work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffc90005747c40 ((work_completion)(&(&nsim_dev->trap_data->trap_report_dw)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline] #1: ffffc90005747c40 ((work_completion)(&(&nsim_dev->trap_data->trap_report_dw)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578 #2: ffff888012632258 (&devlink->lock_key#2){+.+.}-{4:4}, at: nsim_dev_trap_report_work+0x57/0xb30 drivers/net/netdevsim/dev.c:834 locks held by syz.6.2276/13973: 2, on CPU#0: #0: ffff888025a626e8 (nlk_cb_mutex-ROUTE){+.+.}-{4:4}, at: __netlink_dump_start+0xf4/0x7b0 net/netlink/af_netlink.c:2426 #1: ffffffff90674ce0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline] #1: ffffffff90674ce0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_dumpit+0x92/0x200 net/core/rtnetlink.c:7027 locks held by syz.6.2276/13974: 5, last CPU#0: #0: ffff8880787cf0b0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x118/0x160 fs/file.c:1408 #1: ffff88807971c460 (sb_writers#9){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2753 [inline] #1: ffff88807971c460 (sb_writers#9){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0 fs/read_write.c:683 #2: ffff888059e86080 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1d8/0x540 fs/kernfs/file.c:336 #3: ffffffff8f292b40 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:316 [inline] #3: ffffffff8f292b40 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook mm/slub.c:4673 [inline] #3: ffffffff8f292b40 (fs_reclaim){+.+.}-{0:0}, at: slab_alloc_node mm/slub.c:5011 [inline] #3: ffffffff8f292b40 (fs_reclaim){+.+.}-{0:0}, at: __kmalloc_cache_noprof+0x61/0x600 mm/slub.c:5676 #4: ffffffff8f2a92c0 (mmu_notifier_invalidate_range_start){+.+.}-{0:0}, at: fs_reclaim_acquire+0x7c/0x100 mm/page_alloc.c:4382 locks held by syz.7.2278/13976: 2, last CPU#0: #0: ffff88807b088308 (vm_lock){++++}-{0:0}, at: lock_vma_under_rcu+0x1d1/0x500 mm/mmap_lock.c:309 #1: ffffffff8f2af8d0 (remove_cache_srcu){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:213 [inline] #1: ffffffff8f2af8d0 (remove_cache_srcu){.+.+}-{0:0}, at: srcu_read_lock+0x27/0x60 include/linux/srcu.h:320 ============================================= NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 33 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:123 nmi_trigger_cpumask_backtrace+0x17d/0x390 lib/nmi_backtrace.c:66 trigger_all_cpu_backtrace include/linux/nmi.h:164 [inline] __sys_info lib/sys_info.c:157 [inline] sys_info+0x135/0x170 lib/sys_info.c:165 check_hung_uninterruptible_tasks kernel/hung_task.c:377 [inline] watchdog+0x1058/0x10d0 kernel/hung_task.c:598 kthread+0x38b/0x480 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245