INFO: task syz.0.21:5322 blocked for more than 143 seconds.
      Not tainted 5.15.185-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.21        state:D stack:26240 pid: 5322 ppid:  5120 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x11b8/0x43b0 kernel/sched/core.c:6376
 schedule+0x11b/0x1e0 kernel/sched/core.c:6459
 schedule_timeout+0x97/0x280 kernel/time/timer.c:1890
 do_wait_for_common+0x29a/0x440 kernel/sched/completion.c:85
 __wait_for_common kernel/sched/completion.c:106 [inline]
 wait_for_common kernel/sched/completion.c:117 [inline]
 wait_for_completion+0x48/0x60 kernel/sched/completion.c:138
 kthread_stop+0x16e/0x540 kernel/kthread.c:666
 ext4_stop_mmpd+0x43/0xb0 fs/ext4/mmp.c:263
 ext4_fill_super+0x6608/0x9a00 fs/ext4/super.c:5088
 mount_bdev+0x287/0x3c0 fs/super.c:1400
 legacy_get_tree+0xe6/0x180 fs/fs_context.c:611
 vfs_get_tree+0x88/0x270 fs/super.c:1530
 do_new_mount+0x24a/0xa40 fs/namespace.c:3010
 do_mount fs/namespace.c:3353 [inline]
 __do_sys_mount fs/namespace.c:3561 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3538
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f454e41f90a
RSP: 002b:00007f454d68ee68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f454d68eef0 RCX: 00007f454e41f90a
RDX: 0000400000000040 RSI: 0000400000000000 RDI: 00007f454d68eeb0
RBP: 0000400000000040 R08: 00007f454d68eef0 R09: 0000000003010008
R10: 0000000003010008 R11: 0000000000000246 R12: 0000400000000000
R13: 00007f454d68eeb0 R14: 0000000000000538 R15: 0000400000000340
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:
 #0: ffffffff8c11bfa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by kworker/u4:5/3086:
2 locks held by getty/3934:
 #0: ffff88814c8bb098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc90002ce62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x5ba/0x1a30 drivers/tty/n_tty.c:2158
1 lock held by syz.0.21/5322:
 #0: ffff8880773900e0 (&type->s_umount_key#28/1){+.+.}-{3:3}, at: alloc_super+0x201/0x950 fs/super.c:229
1 lock held by syz.1.23/5342:
 #0: ffff88805bd7a0e0 (&type->s_umount_key#28/1){+.+.}-{3:3}, at: alloc_super+0x201/0x950 fs/super.c:229
1 lock held by syz.2.24/5359:
 #0: ffff8880715440e0 (&type->s_umount_key#28/1){+.+.}-{3:3}, at: alloc_super+0x201/0x950 fs/super.c:229
1 lock held by syz.3.25/5383:
 #0: ffff8880250d40e0 (&type->s_umount_key#28/1){+.+.}-{3:3}, at: alloc_super+0x201/0x950 fs/super.c:229
1 lock held by syz.4.26/5406:
 #0: ffff88807621a0e0 (&type->s_umount_key#28/1){+.+.}-{3:3}, at: alloc_super+0x201/0x950 fs/super.c:229
1 lock held by syz.5.27/5428:
 #0: ffff8880586120e0 (&type->s_umount_key#28/1){+.+.}-{3:3}, at: alloc_super+0x201/0x950 fs/super.c:229
1 lock held by syz.6.30/5458:
 #0: ffff88801fdb40e0 (&type->s_umount_key#28/1){+.+.}-{3:3}, at: alloc_super+0x201/0x950 fs/super.c:229
1 lock held by syz.7.31/5488:
 #0: ffff88807d6220e0 (&type->s_umount_key#28/1){+.+.}-{3:3}, at: alloc_super+0x201/0x950 fs/super.c:229
1 lock held by syz.8.32/5511:
 #0: ffff8880239d00e0 (&type->s_umount_key#28/1){+.+.}-{3:3}, at: alloc_super+0x201/0x950 fs/super.c:229

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

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted 5.15.185-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x397/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline]
 watchdog+0xe0f/0xe50 kernel/hung_task.c:369
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 1 skipped: idling at default_idle+0xb/0x10 arch/x86/kernel/process.c:722