[v5.15] INFO: task hung in iterate_supers

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: d9b4a0c83a2d Linux 5.15.98
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1299f262c80000
kernel config: https://syzkaller.appspot.com/x/.config?x=2f8d9515b973b23b
dashboard link: https://syzkaller.appspot.com/bug?extid=b2fb36aa868ed8376328
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/037cabbd3313/disk-d9b4a0c8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9967e551eb34/vmlinux-d9b4a0c8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a050c7a4fd99/bzImage-d9b4a0c8.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b2fb36...@syzkaller.appspotmail.com

INFO: task syz-executor.2:25314 blocked for more than 143 seconds.
Not tainted 5.15.98-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.2 state:D stack:28160 pid:25314 ppid: 3615 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5023 [inline]
__schedule+0x132d/0x45e0 kernel/sched/core.c:6369
schedule+0x11b/0x1f0 kernel/sched/core.c:6452
rwsem_down_read_slowpath+0x605/0xb40 kernel/locking/rwsem.c:1048
__down_read_common+0x54/0x290 kernel/locking/rwsem.c:1230
iterate_supers+0xac/0x1e0 fs/super.c:694
ksys_sync+0xb9/0x1c0 fs/sync.c:102
__do_sys_sync+0xa/0x10 fs/sync.c:113
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f276ee510f9
RSP: 002b:00007f276d3c3168 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f276ef70f80 RCX: 00007f276ee510f9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f276eeacae9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffcde9714cf R14: 00007f276d3c3300 R15: 0000000000022000
</TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:
#0: ffffffff8c91c660 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by getty/3270:
#0: ffff88814aad8098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
#1: ffffc90002bb32e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6af/0x1da0 drivers/tty/n_tty.c:2147
2 locks held by kworker/u4:11/4389:
3 locks held by syz-executor.0/22380:
1 lock held by syz-executor.2/25314:
#0: ffff88804b25e0e0 (&type->s_umount_key#53){++++}-{3:3}, at: iterate_supers+0xac/0x1e0 fs/super.c:694

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

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted 5.15.98-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
nmi_cpu_backtrace+0x46a/0x4a0 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x181/0x2a0 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:210 [inline]
watchdog+0xec6/0xf10 kernel/hung_task.c:295
kthread+0x3f6/0x4f0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 <unknown>:298
</TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 8985 Comm: kworker/u4:15 Not tainted 5.15.98-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet
RIP: 0010:rcu_dynticks_curr_cpu_in_eqs kernel/rcu/tree.c:330 [inline]
RIP: 0010:rcu_is_watching+0x36/0xa0 kernel/rcu/tree.c:1121
Code: e8 af cd af 08 89 c3 83 f8 08 73 72 49 bf 00 00 00 00 00 fc ff df 4c 8d 34 dd e0 77 35 8c 4c 89 f0 48 c1 e8 03 42 80 3c 38 00 <74> 08 4c 89 f7 e8 60 68 5e 00 48 c7 c3 48 a6 03 00 49 03 1e 48 89
RSP: 0018:ffffc900037dfa40 EFLAGS: 00000246
RAX: 1ffffffff186aefd RBX: 0000000000000001 RCX: 1ffff920006fbec8
RDX: dffffc0000000000 RSI: ffffffff8ad8b8e0 RDI: ffffffff8ad8b8a0
RBP: ffffc900037dfb98 R08: dffffc0000000000 R09: fffffbfff1f58815
R10: 0000000000000000 R11: dffffc0000000001 R12: ffff88806465e1d0
R13: dffffc0000000000 R14: ffffffff8c3577e8 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005579b078e1b0 CR3: 0000000078b14000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
rcu_read_lock include/linux/rcupdate.h:688 [inline]
batadv_iv_ogm_slide_own_bcast_window net/batman-adv/bat_iv_ogm.c:755 [inline]
batadv_iv_ogm_schedule_buff net/batman-adv/bat_iv_ogm.c:826 [inline]
batadv_iv_ogm_schedule+0x3d9/0xec0 net/batman-adv/bat_iv_ogm.c:869
batadv_iv_send_outstanding_bat_ogm_packet+0x6fa/0x800 net/batman-adv/bat_iv_ogm.c:1713
process_one_work+0x8e6/0x1230 kernel/workqueue.c:2306
worker_thread+0xaca/0x1280 kernel/workqueue.c:2453
kthread+0x3f6/0x4f0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 <unknown>:298
</TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8a923980a190 Linux 6.1.16
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=138312b8c80000
kernel config: https://syzkaller.appspot.com/x/.config?x=890c08c5270b796
dashboard link: https://syzkaller.appspot.com/bug?extid=3f0d6aae71bcc34c89df

compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:

disk image: https://storage.googleapis.com/syzbot-assets/b5419f7c9b17/disk-8a923980.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/eda486f8541a/vmlinux-8a923980.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e1451605e837/bzImage-8a923980.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:

Reported-by: syzbot+3f0d6a...@syzkaller.appspotmail.com

INFO: task syz-executor.2:21274 blocked for more than 145 seconds.
Not tainted 6.1.16-syzkaller #0

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

task:syz-executor.2 state:D stack:26792 pid:21274 ppid:3683 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5238 [inline]
__schedule+0x1391/0x4390 kernel/sched/core.c:6551
schedule+0xbf/0x180 kernel/sched/core.c:6627
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6686
rwsem_down_read_slowpath+0x5f0/0x940 kernel/locking/rwsem.c:1094
__down_read_common+0x61/0x2c0 kernel/locking/rwsem.c:1261
iterate_supers+0xac/0x1e0 fs/super.c:735

ksys_sync+0xb9/0x1c0 fs/sync.c:102
__do_sys_sync+0xa/0x10 fs/sync.c:113
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80

entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f003ca8c0f9
RSP: 002b:00007f003d7a1168 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f003cbabf80 RCX: 00007f003ca8c0f9

RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000

RBP: 00007f003cae7ae9 R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000

R13: 00007ffd1ca7958f R14: 00007f003d7a1300 R15: 0000000000022000

</TASK>

Showing all locks held in the system:

1 lock held by rcu_tasks_kthre/12:
#0: ffffffff8cf27470 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xd20 kernel/rcu/tasks.h:510
1 lock held by rcu_tasks_trace/13:
#0: ffffffff8cf27c70 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xd20 kernel/rcu/tasks.h:510
1 lock held by khungtaskd/28:
#0: ffffffff8cf272a0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by getty/3316:
#0: ffff88814aa53098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
#1: ffffc900031262f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6a7/0x1db0 drivers/tty/n_tty.c:2177
2 locks held by kworker/0:7/3743:
#0: ffff888012466538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x77b/0x1380
#1: ffffc90004f57d20 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work+0x7be/0x1380 kernel/workqueue.c:2264
6 locks held by kworker/1:8/3762:
#0: ffff888145c3b138 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x77b/0x1380
#1: ffffc90004f27d20 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x7be/0x1380 kernel/workqueue.c:2264
#2: ffff888022528190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:836 [inline]
#2: ffff888022528190 (&dev->mutex){....}-{3:3}, at: hub_event+0x20e/0x57b0 drivers/usb/core/hub.c:5683
#3: ffff88802a1a3190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:836 [inline]
#3: ffff88802a1a3190 (&dev->mutex){....}-{3:3}, at: __device_attach+0x8a/0x570 drivers/base/dd.c:983
#4: ffff88802a1a6118 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:836 [inline]
#4: ffff88802a1a6118 (&dev->mutex){....}-{3:3}, at: __device_attach+0x8a/0x570 drivers/base/dd.c:983
#5: ffffffff8e031168 (register_mutex#6){+.+.}-{3:3}, at: usb_audio_probe+0x410/0x2090 sound/usb/card.c:800
6 locks held by syz-executor.3/11605:
3 locks held by kworker/0:3/19914:
#0: ffff888012464d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x77b/0x1380
#1: ffffc90016e8fd20 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x7be/0x1380 kernel/workqueue.c:2264
#2: ffffffff8cf2c878 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:292 [inline]
#2: ffffffff8cf2c878 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3b0/0x8a0 kernel/rcu/tree_exp.h:948
1 lock held by syz-executor.2/21274:
#0: ffff88807d6820e0 (&type->s_umount_key#56){++++}-{3:3}, at: iterate_supers+0xac/0x1e0 fs/super.c:735
5 locks held by kworker/u4:9/22189:
4 locks held by udevd/22209:
#0: ffff888078922d58 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0xae/0xd10 fs/seq_file.c:182
#1: ffff8880770a1488 (&of->mutex){+.+.}-{3:3}, at: kernfs_seq_start+0x4f/0x3a0 fs/kernfs/file.c:150
#2: ffff8880827e32c0 (kn->active#30){.+.+}-{0:0}, at: kernfs_seq_start+0x6e/0x3a0 fs/kernfs/file.c:151
#3: ffff88802a1a3190 (&dev->mutex){....}-{3:3}, at: device_lock_interruptible include/linux/device.h:841 [inline]
#3: ffff88802a1a3190 (&dev->mutex){....}-{3:3}, at: manufacturer_show+0x22/0x90 drivers/usb/core/sysfs.c:141

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

NMI backtrace for cpu 0

CPU: 0 PID: 28 Comm: khungtaskd Not tainted 6.1.16-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106

nmi_cpu_backtrace+0x4e1/0x560 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x1b0/0x3f0 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
watchdog+0xff3/0x1040 kernel/hung_task.c:377
kthread+0x268/0x300 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306

</TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1

CPU: 1 PID: 3762 Comm: kworker/1:8 Not tainted 6.1.16-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023

Workqueue: usb_hub_wq hub_event
RIP: 0010:format_decode+0xec1/0x1f10
Code: 48 8b 44 24 18 4c 89 28 8b 44 24 48 0f b6 d8 48 89 df 48 c7 c6 60 2e 3c 8e e8 eb 44 06 f7 83 c3 b8 83 fb 32 0f 87 3d 01 00 00 <ff> 24 dd f8 e5 06 8c e8 73 40 06 f7 48 ba 00 00 00 00 00 fc ff df
RSP: 0018:ffffc90004f26200 EFLAGS: 00000283
RAX: 0000000000000002 RBX: 0000000000000024 RCX: 000000000000008b
RDX: 0000000000000006 RSI: ffffffff8e3c2e60 RDI: 000000000000006c
RBP: ffffc90004f262f0 R08: 0000000000000001 R09: ffffffff8a842095
R10: 0000000000000006 R11: ffff888027773a80 R12: ffff000000000500
R13: ffff000000000500 R14: ffffffff8aec99c4 R15: 1ffffffff15d9338
FS: 0000000000000000(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 0000001b30e21000 CR3: 000000001915f000 CR4: 00000000003506e0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>

vsnprintf+0x14d/0x1c70 lib/vsprintf.c:2752
sprintf+0xd6/0x120 lib/vsprintf.c:3004
print_time kernel/printk/printk.c:1274 [inline]
info_print_prefix+0x167/0x300 kernel/printk/printk.c:1300
record_print_text kernel/printk/printk.c:1349 [inline]
console_emit_next_record+0x6e2/0xda0 kernel/printk/printk.c:2714
console_unlock+0x278/0x6e0 kernel/printk/printk.c:2860
vprintk_emit+0xd1/0x1f0 kernel/printk/printk.c:2268
dev_vprintk_emit+0x2aa/0x323 drivers/base/core.c:4884
dev_printk_emit+0xd9/0x118 drivers/base/core.c:4895
_dev_err+0x11e/0x165 drivers/base/core.c:4950
snd_usb_create_streams sound/usb/card.c:282 [inline]
usb_audio_probe+0x106d/0x2090 sound/usb/card.c:880
usb_probe_interface+0x5c0/0xaf0 drivers/usb/core/driver.c:396
really_probe+0x2ab/0xcb0 drivers/base/dd.c:639
__driver_probe_device+0x1c3/0x3f0 drivers/base/dd.c:778
driver_probe_device+0x50/0x420 drivers/base/dd.c:808
__device_attach_driver+0x2cf/0x510 drivers/base/dd.c:936
bus_for_each_drv+0x183/0x200 drivers/base/bus.c:427
__device_attach+0x359/0x570 drivers/base/dd.c:1008
bus_probe_device+0xba/0x1e0 drivers/base/bus.c:487
device_add+0xb48/0xfd0 drivers/base/core.c:3664
usb_set_configuration+0x19dd/0x2020 drivers/usb/core/message.c:2170
usb_generic_driver_probe+0x84/0x140 drivers/usb/core/generic.c:238
usb_probe_device+0x130/0x260 drivers/usb/core/driver.c:293
really_probe+0x2ab/0xcb0 drivers/base/dd.c:639
__driver_probe_device+0x1c3/0x3f0 drivers/base/dd.c:778
driver_probe_device+0x50/0x420 drivers/base/dd.c:808
__device_attach_driver+0x2cf/0x510 drivers/base/dd.c:936
bus_for_each_drv+0x183/0x200 drivers/base/bus.c:427
__device_attach+0x359/0x570 drivers/base/dd.c:1008
bus_probe_device+0xba/0x1e0 drivers/base/bus.c:487
device_add+0xb48/0xfd0 drivers/base/core.c:3664
usb_new_device+0xbdd/0x18e0 drivers/usb/core/hub.c:2575
hub_port_connect drivers/usb/core/hub.c:5355 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5499 [inline]
port_event drivers/usb/core/hub.c:5655 [inline]
hub_event+0x2d4d/0x57b0 drivers/usb/core/hub.c:5737
process_one_work+0x909/0x1380 kernel/workqueue.c:2289
worker_thread+0xa5f/0x1210 kernel/workqueue.c:2436
kthread+0x268/0x300 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 8020ae3c051d Linux 5.15.103
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=164370a6c80000
kernel config: https://syzkaller.appspot.com/x/.config?x=d4215fb4040f8f8d

dashboard link: https://syzkaller.appspot.com/bug?extid=b2fb36aa868ed8376328
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=152c4816c80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11606e4ac80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/857e17de0f0a/disk-8020ae3c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9efc49fcd441/vmlinux-8020ae3c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f14c38b6bfa7/bzImage-8020ae3c.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b2fb36...@syzkaller.appspotmail.com

INFO: task syz-executor862:21862 blocked for more than 143 seconds.
Not tainted 5.15.103-syzkaller #0

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

task:syz-executor862 state:D stack:28032 pid:21862 ppid: 3658 flags:0x00004004

Call Trace:
<TASK>
context_switch kernel/sched/core.c:5023 [inline]

__schedule+0x1348/0x4610 kernel/sched/core.c:6369
schedule+0x11b/0x1f0 kernel/sched/core.c:6452
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6511
rwsem_down_read_slowpath+0x605/0xb40 kernel/locking/rwsem.c:1047
__down_read_common+0x61/0x2c0 kernel/locking/rwsem.c:1231

iterate_supers+0xac/0x1e0 fs/super.c:694
ksys_sync+0xb9/0x1c0 fs/sync.c:102
__do_sys_sync+0xa/0x10 fs/sync.c:113
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x61/0xcb

RIP: 0033:0x7f4efe5e5db9
RSP: 002b:00007f4efdd73208 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f4efe675298 RCX: 00007f4efe5e5db9
RDX: 00007f4efe5e5db9 RSI: 00007f4efe63c1b4 RDI: 0000000000000081
RBP: 00007f4efe675290 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f4efe67529c
R13: 00007ffca4092d0f R14: 00007f4efdd73300 R15: 0000000000022000

</TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:

#0: ffffffff8c91c320 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
1 lock held by klogd/2949:
#0: ffff8880b9b39698 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x26/0x140 kernel/sched/core.c:475

2 locks held by getty/3270:

#0: ffff8880241fc098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252

#1: ffffc90002bb32e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6af/0x1da0 drivers/tty/n_tty.c:2147

1 lock held by syz-executor862/21861:
#0: ffff88801bd7c0e0 (&type->s_umount_key#44/1){+.+.}-{3:3}, at: alloc_super+0x210/0x940 fs/super.c:229
1 lock held by syz-executor862/21862:
#0: ffff88801bd7c0e0 (&type->s_umount_key#67){.+.+}-{3:3}, at: iterate_supers+0xac/0x1e0 fs/super.c:694

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

NMI backtrace for cpu 0

CPU: 0 PID: 27 Comm: khungtaskd Not tainted 5.15.103-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
nmi_cpu_backtrace+0x46a/0x4a0 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x181/0x2a0 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:210 [inline]

watchdog+0xf54/0xfa0 kernel/hung_task.c:295
kthread+0x3f6/0x4f0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

</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 acpi_safe_halt drivers/acpi/processor_idle.c:109 [inline]
NMI backtrace for cpu 1 skipped: idling at acpi_idle_do_entry+0x10f/0x340 drivers/acpi/processor_idle.c:570