[v6.1] INFO: task hung in exfat_write_inode (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: cd5d98c0556c Linux 6.1.86
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=16d85f4d180000
kernel config: https://syzkaller.appspot.com/x/.config?x=1002eed7bd96ee12
dashboard link: https://syzkaller.appspot.com/bug?extid=d00e0762ccdcc5eec44e
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/22fd59eeffbc/disk-cd5d98c0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/064559777212/vmlinux-cd5d98c0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/11c6ce06eda3/bzImage-cd5d98c0.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d00e07...@syzkaller.appspotmail.com

INFO: task kworker/u4:3:46 blocked for more than 143 seconds.
Not tainted 6.1.86-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:3 state:D stack:20512 pid:46 ppid:2 flags:0x00004000
Workqueue: writeback wb_workfn (flush-7:1)
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5245 [inline]
__schedule+0x142d/0x4550 kernel/sched/core.c:6558
schedule+0xbf/0x180 kernel/sched/core.c:6634
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6693
__mutex_lock_common kernel/locking/mutex.c:679 [inline]
__mutex_lock+0x6b9/0xd80 kernel/locking/mutex.c:747
exfat_write_inode+0x65/0x110 fs/exfat/inode.c:94
write_inode fs/fs-writeback.c:1460 [inline]
__writeback_single_inode+0x67d/0x11e0 fs/fs-writeback.c:1677
writeback_sb_inodes+0xc2b/0x1b20 fs/fs-writeback.c:1903
__writeback_inodes_wb+0x114/0x400 fs/fs-writeback.c:1974
wb_writeback+0x4b1/0xe10 fs/fs-writeback.c:2079
wb_check_old_data_flush fs/fs-writeback.c:2179 [inline]
wb_do_writeback fs/fs-writeback.c:2232 [inline]
wb_workfn+0xbec/0x1020 fs/fs-writeback.c:2260
process_one_work+0x8a9/0x11d0 kernel/workqueue.c:2292
worker_thread+0xa47/0x1200 kernel/workqueue.c:2439
kthread+0x28d/0x320 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
</TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
#0: ffffffff8d12ae10 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xe30 kernel/rcu/tasks.h:516
1 lock held by rcu_tasks_trace/13:
#0: ffffffff8d12b610 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xe30 kernel/rcu/tasks.h:516
1 lock held by khungtaskd/28:
#0: ffffffff8d12ac40 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
#0: ffffffff8d12ac40 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
#0: ffffffff8d12ac40 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6494
4 locks held by kworker/u4:3/46:
#0: ffff888141e96138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
#1: ffffc90000b77d20 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
#2: ffff8880738700e0 (&type->s_umount_key#50){++++}-{3:3}, at: trylock_super+0x1b/0xf0 fs/super.c:415
#3: ffff8880707b00e0 (&sbi->s_lock){+.+.}-{3:3}, at: exfat_write_inode+0x65/0x110 fs/exfat/inode.c:94
2 locks held by getty/3307:
#0: ffff88814ba47098 (&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:2188
3 locks held by syz-executor.1/3564:

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

NMI backtrace for cpu 1
CPU: 1 PID: 28 Comm: khungtaskd Not tainted 6.1.86-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
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+0xf88/0xfd0 kernel/hung_task.c:377
kthread+0x28d/0x320 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
</TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 2992 Comm: klogd Not tainted 6.1.86-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
RIP: 0010:__lock_acquire+0x1234/0x1f80 kernel/locking/lockdep.c:5046
Code: 0f b6 04 10 84 c0 0f 85 53 0b 00 00 83 3d 53 a5 5e 10 00 0f 84 b1 00 00 00 31 db 48 83 c3 40 48 89 d8 48 c1 e8 03 80 3c 10 00 <74> 08 48 89 df e8 a2 88 77 00 48 83 3b 00 0f 84 9a 03 00 00 4c 89
RSP: 0018:ffffc9000b79f840 EFLAGS: 00000046
RAX: 1ffffffff20346b4 RBX: ffffffff901a35a0 RCX: ffffffff816a7bc0
RDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffffffff9049a250
RBP: c43e8954cd7f2d9e R08: dffffc0000000000 R09: fffffbfff209344b
R10: 0000000000000000 R11: dffffc0000000001 R12: ffff88807cad2898
R13: ffff88807cad1dc0 R14: 0000000000000001 R15: 1ffff1100f95a518
FS: 00007f1295e12380(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005582998ec600 CR3: 000000002819a000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<NMI>
</NMI>
<TASK>
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
__might_fault+0xbd/0x110 mm/memory.c:5835
_copy_to_user+0x26/0x130 lib/usercopy.c:36
copy_to_user include/linux/uaccess.h:169 [inline]
syslog_print+0x7c4/0x9b0 kernel/printk/printk.c:1577
do_syslog+0x819/0x910 kernel/printk/printk.c:1679
__do_sys_syslog kernel/printk/printk.c:1771 [inline]
__se_sys_syslog kernel/printk/printk.c:1769 [inline]
__x64_sys_syslog+0x78/0x90 kernel/printk/printk.c:1769
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f1295f73fa7
Code: 73 01 c3 48 8b 0d 81 ce 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 67 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 51 ce 0c 00 f7 d8 64 89 01 48
RSP: 002b:00007ffcef6bad98 EFLAGS: 00000206 ORIG_RAX: 0000000000000067
RAX: ffffffffffffffda RBX: 00007f12961124a0 RCX: 00007f1295f73fa7
RDX: 00000000000003ff RSI: 00007f12961124a0 RDI: 0000000000000002
RBP: 0000000000000000 R08: 0000000000000002 R09: ba6e81ffaf892235
R10: 0000000000004000 R11: 0000000000000206 R12: 00007f12961124a0
R13: 00007f1296102212 R14: 00007f1296112503 R15: 00007f1296112503
</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.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup