INFO: task syz.4.721:8914 blocked for more than 143 seconds.
      Not tainted 6.16.0-rc1-syzkaller-00236-g8c6bc74c7f89 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.721       state:D stack:26936 pid:8914  tgid:8903  ppid:5823   task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 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
 bdev_open+0x41a/0xe40 block/bdev.c:945
 bdev_file_open_by_dev block/bdev.c:1059 [inline]
 bdev_file_open_by_dev+0x182/0x210 block/bdev.c:1034
 bdev_file_open_by_path+0xed/0x330 block/bdev.c:1082
 btrfs_scan_one_device+0xcf/0x680 fs/btrfs/volumes.c:1464
 btrfs_get_tree_super fs/btrfs/super.c:1842 [inline]
 btrfs_get_tree+0x3e8/0x1b70 fs/btrfs/super.c:2088
 vfs_get_tree+0x8b/0x340 fs/super.c:1802
 fc_mount+0x18/0x110 fs/namespace.c:1290
 btrfs_get_tree_subvol fs/btrfs/super.c:2046 [inline]
 btrfs_get_tree+0xa37/0x1b70 fs/btrfs/super.c:2089
 vfs_get_tree+0x8b/0x340 fs/super.c:1802
 do_new_mount fs/namespace.c:3885 [inline]
 path_mount+0x1414/0x2020 fs/namespace.c:4209
 do_mount fs/namespace.c:4222 [inline]
 __do_sys_mount fs/namespace.c:4433 [inline]
 __se_sys_mount fs/namespace.c:4410 [inline]
 __x64_sys_mount+0x28d/0x310 fs/namespace.c:4410
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6625b8e929
RSP: 002b:00007f6626952038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f6625db6160 RCX: 00007f6625b8e929
RDX: 0000200000000040 RSI: 0000200000000100 RDI: 0000200000000080
RBP: 00007f6625c10b39 R08: 00002000000000c0 R09: 0000000000000000
R10: 0000000000010003 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f6625db6160 R15: 00007ffe1aab5cc8
 </TASK>

Showing all locks held in the system:
2 locks held by kworker/u8:1/13:
1 lock held by rcu_tasks_trace/29:
 #0: ffffffff8e5c3cb0 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{4:4}, at: rcu_tasks_one_gp+0x72d/0xe20 kernel/rcu/tasks.h:614
1 lock held by khungtaskd/31:
 #0: ffffffff8e5c4840 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e5c4840 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8e5c4840 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6770
2 locks held by getty/5577:
 #0: ffff8880361600a0 (&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
1 lock held by udevd/5827:
 #0: ffff88802672b358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0x41a/0xe40 block/bdev.c:945
2 locks held by syz.4.721/8914:
 #0: ffffffff8edd1d88 (uuid_mutex){+.+.}-{4:4}, at: btrfs_get_tree_super fs/btrfs/super.c:1836 [inline]
 #0: ffffffff8edd1d88 (uuid_mutex){+.+.}-{4:4}, at: btrfs_get_tree+0x3b3/0x1b70 fs/btrfs/super.c:2088
 #1: ffff88802672b358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0x41a/0xe40 block/bdev.c:945

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted 6.16.0-rc1-syzkaller-00236-g8c6bc74c7f89 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 __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
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.16.0-rc1-syzkaller-00236-g8c6bc74c7f89 #0 PREEMPT(full) 
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: 6b 72 02 e9 03 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 a3 f0 29 00 fb f4 <c3> 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: 000002c2
RAX: 00000000018f94ef RBX: 0000000000000000 RCX: ffffffff8b801c19
RDX: 0000000000000000 RSI: ffffffff8de19e08 RDI: ffffffff8c157920
RBP: fffffbfff1c52ef0 R08: 0000000000000001 R09: ffffed1017086645
R10: ffff8880b843322b R11: 0000000000000001 R12: 0000000000000000
R13: ffffffff8e297780 R14: ffffffff90a81450 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff888124753000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f730f77e2d8 CR3: 0000000073456000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 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
 </TASK>