[v5.15] INFO: task hung in disable_device

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 98f47d0e9b8c Linux 5.15.184
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=14866bf4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=9eb2b5a65dfc4761
dashboard link: https://syzkaller.appspot.com/bug?extid=a2c86703b061988bb964
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d2845fb3af6c/disk-98f47d0e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1f12b743be24/vmlinux-98f47d0e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8f178b57ea38/Image-98f47d0e.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a2c867...@syzkaller.appspotmail.com

INFO: task syz.4.120:4567 blocked for more than 143 seconds.
Not tainted 5.15.184-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.120 state:D stack: 0 pid: 4567 ppid: 4036 flags:0x00000009
Call trace:
__switch_to+0x2f4/0x558 arch/arm64/kernel/process.c:521
context_switch kernel/sched/core.c:5030 [inline]
__schedule+0xe00/0x1c0c kernel/sched/core.c:6376
schedule+0x11c/0x1c8 kernel/sched/core.c:6459
schedule_timeout+0xb4/0x2c8 kernel/time/timer.c:1890
do_wait_for_common+0x1fc/0x35c 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+0x48/0x60 kernel/sched/completion.c:138
disable_device+0x1b4/0x320 drivers/infiniband/core/device.c:1297
__ib_unregister_device+0x68/0x170 drivers/infiniband/core/device.c:1483
ib_unregister_device_and_put+0xc0/0x12c drivers/infiniband/core/device.c:1547
nldev_dellink+0x214/0x2a4 drivers/infiniband/core/nldev.c:1740
rdma_nl_rcv_msg drivers/infiniband/core/netlink.c:-1 [inline]
rdma_nl_rcv_skb drivers/infiniband/core/netlink.c:239 [inline]
rdma_nl_rcv+0x548/0x7d4 drivers/infiniband/core/netlink.c:259
netlink_unicast_kernel net/netlink/af_netlink.c:1311 [inline]
netlink_unicast+0x60c/0x89c net/netlink/af_netlink.c:1337
netlink_sendmsg+0x6e8/0x9cc net/netlink/af_netlink.c:1905
sock_sendmsg_nosec net/socket.c:704 [inline]
__sock_sendmsg net/socket.c:716 [inline]
____sys_sendmsg+0x61c/0x920 net/socket.c:2436
___sys_sendmsg+0x1d0/0x240 net/socket.c:2490
__sys_sendmsg net/socket.c:2519 [inline]
__do_sys_sendmsg net/socket.c:2528 [inline]
__se_sys_sendmsg net/socket.c:2526 [inline]
__arm64_sys_sendmsg+0x1a8/0x254 net/socket.c:2526
__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+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608
el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
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: ffff8000143211e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0xc/0x44 include/linux/rcupdate.h:311
2 locks held by kworker/u4:4/339:
#0: ffff0000c0029138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x678/0x1140 kernel/workqueue.c:2283
#1: ffff80001f537c00 ((reaper_work).work){+.+.}-{0:0}, at: process_one_work+0x6b8/0x1140 kernel/workqueue.c:2285
2 locks held by kworker/u4:6/1610:
#0: ffff0000c0029138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x678/0x1140 kernel/workqueue.c:2283
#1: ffff0001a111cc48 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x414/0x68c kernel/sched/psi.c:891
3 locks held by kworker/0:3/3607:
#0: ffff0000c0020938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x678/0x1140 kernel/workqueue.c:2283
#1: ffff800020f27c00 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work+0x6b8/0x1140 kernel/workqueue.c:2285
#2: ffff0000c9200240 (&data->fib_lock){+.+.}-{3:3}, at: nsim_fib_event_work+0x1c8/0x2704 drivers/net/netdevsim/fib.c:1480
2 locks held by getty/3795:
#0: ffff0000d5070098 (&tty->ldisc_sem){++++}-{0:0}, at: ldsem_down_read+0x40/0x50 drivers/tty/tty_ldsem.c:340
#1: ffff80001b7802e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x2f0/0xf6c drivers/tty/n_tty.c:2158
2 locks held by kworker/0:4/4068:
#0: ffff0000c0020938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x678/0x1140 kernel/workqueue.c:2283
#1: ffff80001f3a7c00 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x6b8/0x1140 kernel/workqueue.c:2285
2 locks held by udevd/4172:
#0: ffff0000c81be118 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0xdc/0x6ac block/bdev.c:915
#1: ffff0000cc3ac468 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0xa4/0x978 drivers/block/loop.c:1366
4 locks held by kworker/u4:10/4226:
#0: ffff0000c038c138 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x678/0x1140 kernel/workqueue.c:2283
#1: ffff80001f607c00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x6b8/0x1140 kernel/workqueue.c:2285
#2: ffff80001626c890 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x12c/0xa98 net/core/net_namespace.c:589
#3: ffff0000efe34698 (&device->unregistration_lock){+.+.}-{3:3}, at: rdma_dev_change_netns+0x40/0x2cc drivers/infiniband/core/device.c:1630
2 locks held by syz.4.120/4567:
#0: ffff80001b16a578 (&rdma_nl_types[idx].sem){.+.+}-{3:3}, at: rdma_nl_rcv_msg drivers/infiniband/core/netlink.c:164 [inline]
#0: ffff80001b16a578 (&rdma_nl_types[idx].sem){.+.+}-{3:3}, at: rdma_nl_rcv_skb drivers/infiniband/core/netlink.c:239 [inline]
#0: ffff80001b16a578 (&rdma_nl_types[idx].sem){.+.+}-{3:3}, at: rdma_nl_rcv+0x294/0x7d4 drivers/infiniband/core/netlink.c:259
#1: ffff0000efe34698 (&device->unregistration_lock){+.+.}-{3:3}, at: __ib_unregister_device+0x30/0x170 drivers/infiniband/core/device.c:1479
2 locks held by syz.0.445/5879:
#0: ffff0000cc264118 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0xdc/0x6ac block/bdev.c:915
#1: ffff0000cc35b468 (&lo->lo_mutex){+.+.}-{3:3}, at: lo_release+0x50/0x204 drivers/block/loop.c:2071

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[syzbot]

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