[v5.15] INFO: task hung in user_get_super (4)

Hello,

syzbot found the following issue on:

HEAD commit: 3b8db0e4f263 Linux 5.15.182
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=102a6e70580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f93aaf95aed43225
dashboard link: https://syzkaller.appspot.com/bug?extid=acd565e57b3482d931db
compiler: Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17bcaef4580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16291f68580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/4b5fc99635e8/disk-3b8db0e4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5351a5e4c264/vmlinux-3b8db0e4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e022b133e1a6/bzImage-3b8db0e4.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/c508141ed748/mount_0.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=12fe8ef4580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email protected]

INFO: task syz-executor450:4194 blocked for more than 143 seconds.
Not tainted 5.15.182-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor450 state:D stack:29136 pid: 4194 ppid: 4189 flags:0x00004006
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_preempt_disabled+0xf/0x20 kernel/sched/core.c:6518
rwsem_down_read_slowpath+0x528/0x990 kernel/locking/rwsem.c:1055
__down_read_common kernel/locking/rwsem.c:1239 [inline]
__down_read kernel/locking/rwsem.c:1252 [inline]
down_read+0x96/0x2e0 kernel/locking/rwsem.c:1500
user_get_super+0x118/0x240 fs/super.c:850
quotactl_block fs/quota/quota.c:889 [inline]
__do_sys_quotactl fs/quota/quota.c:953 [inline]
__se_sys_quotactl+0x45e/0x6c0 fs/quota/quota.c:915
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: 0033:0x7ff9b892e409
RSP: 002b:00007ff9b88ca218 EFLAGS: 00000246 ORIG_RAX: 00000000000000b3
RAX: ffffffffffffffda RBX: 00007ff9b89b65f8 RCX: 00007ff9b892e409
RDX: 0000000000000000 RSI: 0000200000000140 RDI: ffffffff80000800
RBP: 00007ff9b89b65f0 R08: 00007ffddd1415d7 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0030656c69662f2e
R13: 0000200000000040 R14: 7366726573696572 R15: 0000200000000080
</TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:
#0: ffffffff8c11bea0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by getty/3933:
#0: ffff88802c2ca098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
#1: ffffc90002cd62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x5ba/0x1a30 drivers/tty/n_tty.c:2158
5 locks held by syz-executor450/4191:
1 lock held by syz-executor450/4194:
#0: ffff88807ab620e0 (&type->s_umount_key#42){.+.+}-{3:3}, at: user_get_super+0x118/0x240 fs/super.c:850

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

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted 5.15.182-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
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
CPU: 1 PID: 150 Comm: kworker/1:1H Not tainted 5.15.182-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
Workqueue: 0x0 (kblockd)
RIP: 0010:__wrgsbase_inactive+0x13/0x50 arch/x86/kernel/process_64.c:191
Code: e9 32 1a 88 f7 0f 0b eb ed 0f 01 f8 f3 48 0f ae c8 0f 01 f8 c3 66 90 48 89 fe 83 3d ca e0 c7 03 00 74 16 65 8b 05 7d 7a 61 76 <85> c0 75 0b 65 8b 05 a2 77 61 76 85 c0 75 0f eb 11 0f 1f 00 bf 02
RSP: 0018:ffffc9000162f9d8 EFLAGS: 00000002
RAX: 0000000000000000 RBX: dffffc0000000000 RCX: 1ffff11003a2b314
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9000162fbb0 R08: dffffc0000000000 R09: ffffed1003a2b001
R10: ffffed1003a2b001 R11: 1ffff11003a2b000 R12: ffff88801d1598a6
R13: ffff88801d158000 R14: ffff88801b843b80 R15: ffff88801b845430
FS: 0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055fc4cd7c168 CR3: 00000000755b8000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:


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