[v6.1] INFO: task hung in fuse_simple_request

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 6c44e13dc284 Linux 6.1.46
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1642c769a80000
kernel config: https://syzkaller.appspot.com/x/.config?x=d53bfb03cd3f0d5d
dashboard link: https://syzkaller.appspot.com/bug?extid=bb2fc284294101ec8e93
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/706045968752/disk-6c44e13d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2f25349b69b4/vmlinux-6c44e13d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e6791616e516/bzImage-6c44e13d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+bb2fc2...@syzkaller.appspotmail.com

INFO: task syz-executor.0:9259 blocked for more than 145 seconds.
Not tainted 6.1.46-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.0 state:D stack:27712 pid:9259 ppid:7831 flags:0x00004006
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5241 [inline]
__schedule+0x132c/0x4330 kernel/sched/core.c:6554
schedule+0xbf/0x180 kernel/sched/core.c:6630
request_wait_answer fs/fuse/dev.c:407 [inline]
__fuse_request_send fs/fuse/dev.c:426 [inline]
fuse_simple_request+0x106e/0x18d0 fs/fuse/dev.c:511
fuse_do_getattr+0x39f/0xfa0 fs/fuse/dir.c:1119
vfs_statx+0x194/0x4b0 fs/stat.c:233
vfs_fstatat fs/stat.c:267 [inline]
__do_sys_newfstatat fs/stat.c:437 [inline]
__se_sys_newfstatat fs/stat.c:431 [inline]
__x64_sys_newfstatat+0x151/0x1e0 fs/stat.c:431
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: 0033:0x7efce787cae9
RSP: 002b:00007efce86240c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000106
RAX: ffffffffffffffda RBX: 00007efce799c050 RCX: 00007efce787cae9
RDX: 0000000000000000 RSI: 0000000020000040 RDI: ffffffffffffff9c
RBP: 00007efce78c847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007efce799c050 R15: 00007fff3032c2b8
</TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
#0: ffffffff8d12a0b0 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xd20 kernel/rcu/tasks.h:516
1 lock held by rcu_tasks_trace/13:
#0: ffffffff8d12a8b0 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xd20 kernel/rcu/tasks.h:516
1 lock held by khungtaskd/28:
#0: ffffffff8d129ee0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by kworker/u4:4/86:
#0: ffff888012479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x77a/0x11f0
#1: ffffc90001577d20 (connector_reaper_work){+.+.}-{0:0}, at: process_one_work+0x7bd/0x11f0 kernel/workqueue.c:2267
2 locks held by getty/3265:
#0: ffff888028aa2098 (&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
2 locks held by kworker/0:6/3611:
#0: ffff888012472538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x77a/0x11f0
#1: ffffc90003e8fd20 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work+0x7bd/0x11f0 kernel/workqueue.c:2267
4 locks held by kworker/u4:7/3687:
#0: ffff88801260e938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x77a/0x11f0
#1: ffffc90004427d20 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x7bd/0x11f0 kernel/workqueue.c:2267
#2: ffffffff8e28c610 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0xf1/0xb60 net/core/net_namespace.c:563
#3: ffffffff8d12f380 (rcu_state.barrier_mutex){+.+.}-{3:3}, at: rcu_barrier+0x48/0x5f0 kernel/rcu/tree.c:3965
3 locks held by kworker/0:18/5578:
2 locks held by syz-executor.0/9381:
#0: ffff888088d840e0 (&type->s_umount_key#59){++++}-{3:3}, at: deactivate_super+0xa9/0xe0 fs/super.c:362
#1: ffffffff8d12f4b8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:292 [inline]
#1: ffffffff8d12f4b8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3b0/0x8a0 kernel/rcu/tree_exp.h:950

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

NMI backtrace for cpu 1
CPU: 1 PID: 28 Comm: khungtaskd Not tainted 6.1.46-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
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+0xf18/0xf60 kernel/hung_task.c:377
kthread+0x26e/0x300 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
</TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 86 Comm: kworker/u4:4 Not tainted 6.1.46-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
Workqueue: bat_events batadv_nc_worker
RIP: 0010:lock_acquire+0xc/0x5a0 kernel/locking/lockdep.c:5637
Code: 3a a5 76 00 e9 a2 fd ff ff 0f 1f 44 00 00 65 8b 05 e1 83 98 7e a9 00 ff ff 00 0f 95 c0 c3 55 48 89 e5 41 57 41 56 41 55 41 54 <53> 48 83 e4 e0 48 81 ec 20 01 00 00 4c 89 4c 24 28 4c 89 44 24 38
RSP: 0018:ffffc90001577b50 EFLAGS: 00000246
RAX: ffffffff8a56de3a RBX: ffff888020f7c2d0 RCX: 0000000000000002
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8d129ee0
RBP: ffffc90001577b70 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff1100f78a2f2
R13: ffff88807bc50c80 R14: ffff8880752cbf90 R15: ffffffff8a56d6d0
FS: 0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f81ecd98000 CR3: 000000000ce8e000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<NMI>
</NMI>
<TASK>
rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:306
rcu_read_lock include/linux/rcupdate.h:747 [inline]
batadv_nc_process_nc_paths+0xb8/0x350 net/batman-adv/network-coding.c:687
batadv_nc_worker+0x3d4/0x5b0 net/batman-adv/network-coding.c:728
process_one_work+0x8aa/0x11f0 kernel/workqueue.c:2292
worker_thread+0xa5f/0x1210 kernel/workqueue.c:2439
kthread+0x26e/0x300 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
</TASK>


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[syzbot]

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