INFO: task syz.1.4100:19596 blocked for more than 143 seconds. Tainted: G U 6.16.0-rc5-syzkaller-00038-g733923397fd9 #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.1.4100 state:D stack:26344 pid:19596 tgid:19595 ppid:5844 task_flags:0x400140 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:5401 [inline] __schedule+0x116a/0x5de0 kernel/sched/core.c:6790 __schedule_loop kernel/sched/core.c:6868 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:6883 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6940 __mutex_lock_common kernel/locking/mutex.c:679 [inline] __mutex_lock+0x6c7/0xb90 kernel/locking/mutex.c:747 nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:596 nfsd_umount+0x48/0xe0 fs/nfsd/nfsctl.c:1386 deactivate_locked_super+0xc1/0x1a0 fs/super.c:474 deactivate_super fs/super.c:507 [inline] deactivate_super+0xde/0x100 fs/super.c:503 cleanup_mnt+0x225/0x450 fs/namespace.c:1417 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+0xeb/0x110 kernel/entry/common.c:114 exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline] do_syscall_64+0x3f6/0x490 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f1856f8e929 RSP: 002b:00007f1857ed4038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: fffffffffffffffe RBX: 00007f18571b5fa0 RCX: 00007f1856f8e929 RDX: 0000200000000080 RSI: 0000200000000040 RDI: 0000000000000000 RBP: 00007f1857010b39 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000007 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f18571b5fa0 R15: 00007ffde3f76ef8 Showing all locks held in the system: 6 locks held by kworker/u8:0/12: 1 lock held by khungtaskd/31: #0: ffffffff8e5c4d00 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #0: ffffffff8e5c4d00 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #0: ffffffff8e5c4d00 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6770 4 locks held by kworker/u8:7/3509: #0: ffff88801c6fe148 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3213 #1: ffffc9000c207d10 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3214 #2: ffffffff9034e110 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xad/0x890 net/core/net_namespace.c:662 #3: ffffffff8e5d01c0 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x48/0x6e0 kernel/rcu/tree.c:3786 2 locks held by syz-executor/5832: 2 locks held by syz.3.3625/17501: #0: ffffffff90408970 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218 #1: ffffffff8e9de688 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x687/0xbc0 fs/nfsd/nfsctl.c:1629 2 locks held by syz.1.4100/19596: #0: ffff8880630b80e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: __super_lock fs/super.c:57 [inline] #0: ffff8880630b80e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline] #0: ffff8880630b80e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: deactivate_super fs/super.c:506 [inline] #0: ffff8880630b80e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: deactivate_super+0xd6/0x100 fs/super.c:503 #1: ffffffff8e9de688 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:596 2 locks held by syz-executor/19731: #0: ffff88806e33c0e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: __super_lock fs/super.c:57 [inline] #0: ffff88806e33c0e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline] #0: ffff88806e33c0e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: deactivate_super fs/super.c:506 [inline] #0: ffff88806e33c0e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: deactivate_super+0xd6/0x100 fs/super.c:503 #1: ffffffff8e9de688 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:596 ============================================= NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Tainted: G U 6.16.0-rc5-syzkaller-00038-g733923397fd9 #0 PREEMPT(full) Tainted: [U]=USER 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+0x3c2/0x780 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 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Tainted: G U 6.16.0-rc5-syzkaller-00038-g733923397fd9 #0 PREEMPT(full) Tainted: [U]=USER Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:82 Code: 4b 6f 02 e9 93 fb 02 00 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 93 c7 25 00 fb f4 cc cc cc cc 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90 RSP: 0018:ffffffff8e207e08 EFLAGS: 000002c6 RAX: 00000000004216d1 RBX: 0000000000000000 RCX: ffffffff8b844c49 RDX: 0000000000000000 RSI: ffffffff8de2be6b RDI: ffffffff8c1578e0 RBP: fffffbfff1c52ef0 R08: 0000000000000001 R09: ffffed1017086645 R10: ffff8880b843322b R11: 0000000000000001 R12: 0000000000000000 R13: ffffffff8e297780 R14: ffffffff90a99a50 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff888124721000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fee4e6e7d60 CR3: 0000000025faa000 CR4: 00000000003526f0 Call Trace: arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:749 default_idle_call+0x6d/0xb0 kernel/sched/idle.c:117 cpuidle_idle_call kernel/sched/idle.c:185 [inline] do_idle+0x391/0x510 kernel/sched/idle.c:325 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:423 rest_init+0x16b/0x2b0 init/main.c:745 start_kernel+0x3ee/0x4d0 init/main.c:1102 x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:307 x86_64_start_kernel+0x130/0x190 arch/x86/kernel/head64.c:288 common_startup_64+0x13e/0x148