syzbot

INFO: task syz.6.1908:22200 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.1908      state:D stack:25664 pid:22200 tgid:22199 ppid:13352  task_flags:0x400140 flags:0x00080003
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5298 [inline]
 __schedule+0x1553/0x5240 kernel/sched/core.c:6911
 __schedule_loop kernel/sched/core.c:6993 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7008
 schedule_timeout+0xc3/0x2c0 kernel/time/sleep_timeout.c:75
 do_wait_for_common kernel/sched/completion.c:100 [inline]
 __wait_for_common kernel/sched/completion.c:121 [inline]
 wait_for_common kernel/sched/completion.c:132 [inline]
 wait_for_completion+0x2cc/0x5e0 kernel/sched/completion.c:153
 kthread_flush_worker+0x138/0x1a0 kernel/kthread.c:1579
 __alloc_workqueue+0xfed/0x1e90 kernel/workqueue.c:5861
 alloc_workqueue_noprof+0xe3/0x210 kernel/workqueue.c:5884
 btrfs_alloc_workqueue+0x1ec/0x2d0 fs/btrfs/async-thread.c:112
 btrfs_init_workqueues+0xb0/0x680 fs/btrfs/disk-io.c:1920
 open_ctree+0x1598/0x4220 fs/btrfs/disk-io.c:3447
 btrfs_fill_super fs/btrfs/super.c:981 [inline]
 btrfs_get_tree_super fs/btrfs/super.c:1944 [inline]
 btrfs_get_tree_subvol fs/btrfs/super.c:2087 [inline]
 btrfs_get_tree+0x1061/0x1930 fs/btrfs/super.c:2121
 vfs_get_tree+0x92/0x2a0 fs/super.c:1754
 fc_mount fs/namespace.c:1193 [inline]
 do_new_mount_fc fs/namespace.c:3763 [inline]
 do_new_mount+0x341/0xd30 fs/namespace.c:3839
 do_mount fs/namespace.c:4172 [inline]
 __do_sys_mount fs/namespace.c:4361 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4338
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f91b102da0a
RSP: 002b:00007f91af285e58 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f91af285ee0 RCX: 00007f91b102da0a
RDX: 0000200000005100 RSI: 0000200000000040 RDI: 00007f91af285ea0
RBP: 0000200000005100 R08: 00007f91af285ee0 R09: 0000000000800810
R10: 0000000000800810 R11: 0000000000000246 R12: 0000200000000040
R13: 00007f91af285ea0 R14: 000000000000510a R15: 0000200000000140
 </TASK>

Showing all locks held in the system:
4 locks held by pr/legacy/17:
1 lock held by khungtaskd/38:
 #0: ffffffff8ddcb980 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #0: ffffffff8ddcb980 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #0: ffffffff8ddcb980 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by getty/5550:
 #0: ffff888036ea70a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90003e8b2e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x462/0x13c0 drivers/tty/n_tty.c:2211
1 lock held by udevd/6562:
 #0: ffff8880227ca228 (&sb->s_type->i_mutex_key#9){++++}-{4:4}, at: inode_lock_shared include/linux/fs.h:1043 [inline]
 #0: ffff8880227ca228 (&sb->s_type->i_mutex_key#9){++++}-{4:4}, at: blkdev_read_iter+0x2ff/0x440 block/fops.c:854
2 locks held by udevd/8732:
1 lock held by udevd/10082:
2 locks held by kworker/u8:13/11717:
 #0: ffff888019c44138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3251 [inline]
 #0: ffff888019c44138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0xa52/0x18c0 kernel/workqueue.c:3359
 #1: ffffc90006767c40 ((reaper_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3252 [inline]
 #1: ffffc90006767c40 ((reaper_work).work){+.+.}-{0:0}, at: process_scheduled_works+0xa8d/0x18c0 kernel/workqueue.c:3359
5 locks held by napi/wg1-0/13728:
1 lock held by syz-executor/15312:
2 locks held by kworker/u8:2/21361:
 #0: ffff888019c44138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3251 [inline]
 #0: ffff888019c44138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0xa52/0x18c0 kernel/workqueue.c:3359
 #1: ffffc90011b7fc40 (connector_reaper_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3252 [inline]
 #1: ffffc90011b7fc40 (connector_reaper_work){+.+.}-{0:0}, at: process_scheduled_works+0xa8d/0x18c0 kernel/workqueue.c:3359
1 lock held by syz.6.1908/22200:
 #0: ffff88807a2d40d0 (&type->s_umount_key#60/1){+.+.}-{4:4}, at: alloc_super+0x28c/0xac0 fs/super.c:345
8 locks held by syz-executor/24428:
 #0: ffff8880114f4480 (sb_writers#7){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2710 [inline]
 #0: ffff8880114f4480 (sb_writers#7){.+.+}-{0:0}, at: vfs_write+0x22d/0xba0 fs/read_write.c:684
 #1: ffff88803c20e078 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1df/0x540 fs/kernfs/file.c:343
 #2: ffff88802902ba58 (kn->active#52){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline]
 #2: ffff88802902ba58 (kn->active#52){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x232/0x540 fs/kernfs/file.c:344
 #3: ffffffff8e9c85f8 (nsim_bus_dev_list_lock){+.+.}-{4:4}, at: del_device_store+0xd7/0x370 drivers/net/netdevsim/bus.c:234
 #4: ffff88803ba6d0d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
 #4: ffff88803ba6d0d8 (&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1106 [inline]
 #4: ffff88803ba6d0d8 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xb6/0x870 drivers/base/dd.c:1304
 #5: ffff88803d158300 (&devlink->lock_key#16){+.+.}-{4:4}, at: nsim_drv_remove+0x50/0x160 drivers/net/netdevsim/dev.c:1778
 #6: ffffffff8f15abb8 (rtnl_mutex){+.+.}-{4:4}, at: nsim_destroy+0xed/0x680 drivers/net/netdevsim/netdev.c:1177
 #7: ffff888036570ea0 (&dev_instance_lock_key#24){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2784 [inline]
 #7: ffff888036570ea0 (&dev_instance_lock_key#24){+.+.}-{4:4}, at: unregister_netdevice_many_notify+0x583/0x2360 net/core/dev.c:12374
1 lock held by syz.4.2112/24560:
2 locks held by syz.9.2111/24569:
 #0: ffff88803fcb40d0 (&type->s_umount_key#54/1){+.+.}-{4:4}, at: alloc_super+0x28c/0xac0 fs/super.c:345
 #1: ffffffff8dc6bab8 (wq_pool_mutex){+.+.}-{4:4}, at: apply_wqattrs_lock kernel/workqueue.c:5279 [inline]
 #1: ffffffff8dc6bab8 (wq_pool_mutex){+.+.}-{4:4}, at: __alloc_workqueue+0x9ef/0x1e90 kernel/workqueue.c:5832
1 lock held by rm/24592:

=============================================

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 38 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:161 [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:346 [inline]
 watchdog+0xfd9/0x1030 kernel/hung_task.c:515
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 13728 Comm: napi/wg1-0 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:__bfs kernel/locking/lockdep.c:1753 [inline]
RIP: 0010:__bfs_backwards kernel/locking/lockdep.c:1860 [inline]
RIP: 0010:check_irq_usage kernel/locking/lockdep.c:2796 [inline]
RIP: 0010:check_prev_add kernel/locking/lockdep.c:3169 [inline]
RIP: 0010:check_prevs_add kernel/locking/lockdep.c:3284 [inline]
RIP: 0010:validate_chain kernel/locking/lockdep.c:3908 [inline]
RIP: 0010:__lock_acquire+0x1821/0x2cf0 kernel/locking/lockdep.c:5237
Code: 00 0f 83 8a 01 00 00 4e 8b 24 fd c0 88 56 95 ff c0 25 ff 0f 00 00 89 05 6d b7 b6 13 4d 85 e4 0f 84 b2 01 00 00 49 8b 44 24 10 <48> 85 c0 0f 84 1c 0d 00 00 8b 0d 58 b7 b6 13 39 48 5c 0f 84 67 ff
RSP: 0018:ffffc90003c572c8 EFLAGS: 00000086
RAX: ffffffff92fea6a0 RBX: 00000000000003cd RCX: ffffffff9601d9e8
RDX: ffffffff95e5fff8 RSI: ffff88801e7c8c80 RDI: 00000000000003cd
RBP: bc3f9163dc441ef4 R08: ffffc90003c57290 R09: 0000000000000020
R10: dffffc0000000000 R11: ffffffff81a0a3c0 R12: ffffffff9601d9e8
R13: ffff88801e7c8c80 R14: ffff88801e7c8000 R15: 00000000000000b4
FS:  0000000000000000(0000) GS:ffff88812643c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f78116a1000 CR3: 000000006bb6a000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 lock_acquire+0xf0/0x2e0 kernel/locking/lockdep.c:5868
 _raw_spin_lock_nested+0x32/0x50 kernel/locking/spinlock.c:378
 raw_spin_rq_lock_nested+0x31/0x150 kernel/sched/core.c:647
 raw_spin_rq_lock kernel/sched/sched.h:1615 [inline]
 _task_rq_lock+0xbc/0x470 kernel/sched/core.c:747
 class_task_rq_lock_constructor kernel/sched/sched.h:1917 [inline]
 migrate_disable_switch kernel/sched/core.c:2366 [inline]
 __schedule+0x16d3/0x5240 kernel/sched/core.c:6795
 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7238
 irqentry_exit+0x599/0x620 kernel/entry/common.c:239
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:lock_release+0x2d7/0x3d0 kernel/locking/lockdep.c:5893
Code: 1d ae 10 00 00 00 00 eb b5 e8 a5 79 82 09 f7 c3 00 02 00 00 74 b9 65 48 8b 05 15 d7 ad 10 48 3b 44 24 28 75 44 fb 48 83 c4 30 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc 48 8d 3d 72 fb cc
RSP: 0018:ffffc90003c57870 EFLAGS: 00000282
RAX: ec45087a6ccc9d00 RBX: 0000000000000206 RCX: 0000000000000046
RDX: 000000001538c6fc RSI: ffffffff8d7bd735 RDI: ffffffff8ba66b00
RBP: ffff88801e7c8c30 R08: ffffffff8b2531d0 R09: ffffffff8ddcb980
R10: 0000000000000000 R11: ffffed100661f824 R12: 0000000000000004
R13: 0000000000000004 R14: ffff8880330fc0e8 R15: ffff88801e7c8000
 rt_spin_unlock+0x29/0x200 kernel/locking/spinlock_rt.c:80
 spin_unlock_bh include/linux/spinlock_rt.h:115 [inline]
 counter_validate drivers/net/wireguard/receive.c:329 [inline]
 wg_packet_rx_poll+0x61c/0x24e0 drivers/net/wireguard/receive.c:461
 __napi_poll+0xaf/0x580 net/core/dev.c:7692
 napi_threaded_poll_loop+0x3b2/0x6f0 net/core/dev.c:7812
 napi_threaded_poll+0x335/0x490 net/core/dev.c:7867
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>