[v5.15] INFO: task hung in ext4_stop_mmpd

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4fdad925aa1a Linux 5.15.107
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=14301db7c80000
kernel config: https://syzkaller.appspot.com/x/.config?x=d67d6c9042bf5bb9
dashboard link: https://syzkaller.appspot.com/bug?extid=85ac912baa40299f3ce7
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a4ecac695096/disk-4fdad925.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3362687e1660/vmlinux-4fdad925.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3e588c974210/Image-4fdad925.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+85ac91...@syzkaller.appspotmail.com

INFO: task syz-executor.1:23938 blocked for more than 146 seconds.
Not tainted 5.15.107-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.1 state:D stack: 0 pid:23938 ppid: 4088 flags:0x00000009
Call trace:
__switch_to+0x308/0x5e8 arch/arm64/kernel/process.c:518
context_switch kernel/sched/core.c:5026 [inline]
__schedule+0xf10/0x1e38 kernel/sched/core.c:6372
schedule+0x11c/0x1c8 kernel/sched/core.c:6455
schedule_timeout+0xb8/0x344 kernel/time/timer.c:1860
do_wait_for_common+0x214/0x388 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+0x4c/0x64 kernel/sched/completion.c:138
kthread_stop+0x1a0/0x788 kernel/kthread.c:649
ext4_stop_mmpd+0x48/0xb4 fs/ext4/mmp.c:255
ext4_fill_super+0x587c/0x868c fs/ext4/super.c:5076
mount_bdev+0x26c/0x368 fs/super.c:1378
ext4_mount+0x44/0x58 fs/ext4/super.c:6568
legacy_get_tree+0xd4/0x16c fs/fs_context.c:610
vfs_get_tree+0x90/0x274 fs/super.c:1508
do_new_mount+0x25c/0x8c8 fs/namespace.c:2994
path_mount+0x590/0x104c fs/namespace.c:3324
do_mount fs/namespace.c:3337 [inline]
__do_sys_mount fs/namespace.c:3545 [inline]
__se_sys_mount fs/namespace.c:3522 [inline]
__arm64_sys_mount+0x510/0x5e0 fs/namespace.c:3522
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:596
el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:614
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

Showing all locks held in the system:
1 lock held by khungtaskd/27:
#0: ffff800014aa1660 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0xc/0x44 include/linux/rcupdate.h:268
1 lock held by udevd/3585:
2 locks held by getty/3732:
#0: ffff0000d2f6b098 (&tty->ldisc_sem){++++}-{0:0}, at: ldsem_down_read+0x40/0x50 drivers/tty/tty_ldsem.c:340
#1: ffff80001a24e2e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x414/0x1200 drivers/tty/n_tty.c:2147
3 locks held by kworker/u4:17/5896:
2 locks held by kworker/u4:18/5897:
#0: ffff0000c0029138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x66c/0x11b8 kernel/workqueue.c:2279
#1: ffff80001ef97c00 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_one_work+0x6ac/0x11b8 kernel/workqueue.c:2281
1 lock held by syz-executor.1/23938:
#0: ffff0000ce69a0e0 (&type->s_umount_key#26/1){+.+.}-{3:3}, at: alloc_super+0x1b8/0x844 fs/super.c:229
2 locks held by udevd/23996:
#0: ffff0000cbc9e918 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x12c/0x89c block/bdev.c:817
#1: ffff0000cbc93468 (&lo->lo_mutex){+.+.}-{3:3}, at: lo_open+0x6c/0x14c drivers/block/loop.c:2055
2 locks held by udevd/23998:
#0: ffff0000cbd7c118 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x12c/0x89c block/bdev.c:817
#1: ffff0000cbcfc468 (&lo->lo_mutex){+.+.}-{3:3}, at: lo_open+0x6c/0x14c drivers/block/loop.c:2055
1 lock held by udevd/23999:
1 lock held by syz-executor.2/25193:
#0: ffff0000cbc93468 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0xa8/0x9b8 drivers/block/loop.c:1365
1 lock held by syz-executor.4/25179:
#0: ffff00013b0b60e0 (&type->s_umount_key#26/1){+.+.}-{3:3}, at: alloc_super+0x1b8/0x844 fs/super.c:229
1 lock held by syz-executor.0/25180:
#0: ffff0000dffe9410 (&sb->s_type->i_mutex_key#11){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
#0: ffff0000dffe9410 (&sb->s_type->i_mutex_key#11){+.+.}-{3:3}, at: __sock_release net/socket.c:648 [inline]
#0: ffff0000dffe9410 (&sb->s_type->i_mutex_key#11){+.+.}-{3:3}, at: sock_close+0x80/0x1fc net/socket.c:1317
1 lock held by syz-executor.3/25182:
#0: ffff000120aea010 (&sb->s_type->i_mutex_key#11){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
#0: ffff000120aea010 (&sb->s_type->i_mutex_key#11){+.+.}-{3:3}, at: __sock_release net/socket.c:648 [inline]
#0: ffff000120aea010 (&sb->s_type->i_mutex_key#11){+.+.}-{3:3}, at: sock_close+0x80/0x1fc net/socket.c:1317
1 lock held by syz-executor.5/25199:
#0: ffff0000cbcfc468 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0xa8/0x9b8 drivers/block/loop.c:1365

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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.