[v5.15] INFO: task hung in __fdget_pos

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syzbot

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Mar 31, 2023, 6:54:56 AM3/31/23
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Hello,

syzbot found the following issue on:

HEAD commit: c957cbb87315 Linux 5.15.105
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=12d0b501c80000
kernel config: https://syzkaller.appspot.com/x/.config?x=852dc3de44ba1f3f
dashboard link: https://syzkaller.appspot.com/bug?extid=dffcaad7d9538ed2d23e
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/91d0cf1fc5fb/disk-c957cbb8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/346dc1169521/vmlinux-c957cbb8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f7005bdc0e20/Image-c957cbb8.gz.xz

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

INFO: task syz-executor.2:10576 blocked for more than 144 seconds.
Not tainted 5.15.105-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.2 state:D stack: 0 pid:10576 ppid: 4102 flags:0x00000001
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_preempt_disabled+0x18/0x2c kernel/sched/core.c:6514
__mutex_lock_common+0xba0/0x2154 kernel/locking/mutex.c:669
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743
__fdget_pos+0xdc/0x108 fs/file.c:1073
fdget_pos include/linux/file.h:75 [inline]
ksys_write+0x8c/0x26c fs/read_write.c:638
__do_sys_write fs/read_write.c:659 [inline]
__se_sys_write fs/read_write.c:656 [inline]
__arm64_sys_write+0x7c/0x90 fs/read_write.c:656
__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:
4 locks held by kworker/1:1/25:
#0: ffff0000c0021538 ((wq_completion)events_long){+.+.}-{0:0}, at: process_one_work+0x66c/0x11b8 kernel/workqueue.c:2279
#1: ffff8000189e7c00 ((work_completion)(&(&sbi->old_work)->work)){+.+.}-{0:0}, at: process_one_work+0x6ac/0x11b8 kernel/workqueue.c:2281
#2: ffff00012754c0e0 (&type->s_umount_key#61){++++}-{3:3}, at: flush_old_commits+0xcc/0x2b8 fs/reiserfs/super.c:97
#3: ffff0000d4d7f090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x7c/0xe8 fs/reiserfs/lock.c:27
1 lock held by khungtaskd/27:
#0: ffff800014a91660 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0xc/0x44 include/linux/rcupdate.h:268
2 locks held by kworker/u4:4/333:
2 locks held by getty/3735:
#0:
ffff0000d3284098 (&tty->ldisc_sem){++++}-{0:0}, at: ldsem_down_read+0x40/0x50 drivers/tty/tty_ldsem.c:340
#1: ffff80001a26b2e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x414/0x1200 drivers/tty/n_tty.c:2147
7 locks held by syz-executor.2/10568:
1 lock held by syz-executor.2/10576:
#0: ffff00012c6cd770 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xdc/0x108 fs/file.c:1073
3 locks held by kworker/u4:13/11112:
2 locks held by syz-executor.4/13998:
#0: ffff00012754c0e0 (&type->s_umount_key#61){++++}-{3:3}, at: iterate_supers+0xb0/0x1dc fs/super.c:703
#1:
ffff0000d4d7f090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x7c/0xe8 fs/reiserfs/lock.c:27

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



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syzbot

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Jul 29, 2023, 6:54:42 AM7/29/23
to syzkaller...@googlegroups.com
Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.
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