INFO: task hung in tipc_exit_net (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e911713e40ca Linux 4.14.299
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13e1ddfe880000
kernel config: https://syzkaller.appspot.com/x/.config?x=1d7ed9728cc57838
dashboard link: https://syzkaller.appspot.com/bug?extid=60588a58826447a4fc9b
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c8588259d654/disk-e911713e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/700d08072e5e/vmlinux-e911713e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/844ad5da2ed5/bzImage-e911713e.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+60588a...@syzkaller.appspotmail.com

device macsec1 entered promiscuous mode
device bond0 entered promiscuous mode
device bond0 left promiscuous mode
device bond_slave_0 left promiscuous mode
device bond_slave_1 left promiscuous mode
INFO: task kworker/u4:2:28 blocked for more than 140 seconds.
Not tainted 4.14.299-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u4:2 D26664 28 2 0x80000000
Workqueue: netns cleanup_net
Call Trace:
context_switch kernel/sched/core.c:2811 [inline]
__schedule+0x88b/0x1de0 kernel/sched/core.c:3387
schedule+0x8d/0x1b0 kernel/sched/core.c:3431
schedule_timeout+0x80a/0xe90 kernel/time/timer.c:1724
do_wait_for_common kernel/sched/completion.c:91 [inline]
__wait_for_common kernel/sched/completion.c:112 [inline]
wait_for_common+0x272/0x430 kernel/sched/completion.c:123
flush_workqueue+0x3ce/0x1310 kernel/workqueue.c:2677
flush_scheduled_work include/linux/workqueue.h:578 [inline]
tipc_exit_net+0x38/0x60 net/tipc/core.c:96
ops_exit_list+0xad/0x160 net/core/net_namespace.c:142
cleanup_net+0x3b3/0x840 net/core/net_namespace.c:487
process_one_work+0x793/0x14a0 kernel/workqueue.c:2117
worker_thread+0x5cc/0xff0 kernel/workqueue.c:2251
kthread+0x30d/0x420 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:406
INFO: task syz-executor.2:9606 blocked for more than 140 seconds.
Not tainted 4.14.299-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.2 D28072 9606 8029 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2811 [inline]
__schedule+0x88b/0x1de0 kernel/sched/core.c:3387
schedule+0x8d/0x1b0 kernel/sched/core.c:3431
schedule_timeout+0x80a/0xe90 kernel/time/timer.c:1724
do_wait_for_common kernel/sched/completion.c:91 [inline]
__wait_for_common kernel/sched/completion.c:112 [inline]
wait_for_common+0x272/0x430 kernel/sched/completion.c:123
flush_work+0x3fe/0x770 kernel/workqueue.c:2894
__cancel_work_timer+0x321/0x460 kernel/workqueue.c:2965
p9_conn_destroy net/9p/trans_fd.c:898 [inline]
p9_fd_close+0x28d/0x420 net/9p/trans_fd.c:925
p9_client_create+0x736/0x12c0 net/9p/client.c:1093
v9fs_session_init+0x1c5/0x1540 fs/9p/v9fs.c:422
v9fs_mount+0x73/0x860 fs/9p/vfs_super.c:135
mount_fs+0x92/0x2a0 fs/super.c:1237
vfs_kern_mount.part.0+0x5b/0x470 fs/namespace.c:1046
vfs_kern_mount fs/namespace.c:1036 [inline]
do_new_mount fs/namespace.c:2572 [inline]
do_mount+0xe65/0x2a30 fs/namespace.c:2905
SYSC_mount fs/namespace.c:3121 [inline]
SyS_mount+0xa8/0x120 fs/namespace.c:3098
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x5e/0xd3

Showing all locks held in the system:
2 locks held by kworker/0:1/25:
#0: ("events"){+.+.}, at: [<ffffffff81365eb0>] process_one_work+0x6b0/0x14a0 kernel/workqueue.c:2088
#1: ((&m->rq)){+.+.}, at: [<ffffffff81365ee6>] process_one_work+0x6e6/0x14a0 kernel/workqueue.c:2092
3 locks held by kworker/u4:2/28:
#0: ("%s""netns"){+.+.}, at: [<ffffffff81365eb0>] process_one_work+0x6b0/0x14a0 kernel/workqueue.c:2088
#1: (net_cleanup_work){+.+.}, at: [<ffffffff81365ee6>] process_one_work+0x6e6/0x14a0 kernel/workqueue.c:2092
#2: (net_mutex){+.+.}, at: [<ffffffff85c21df0>] cleanup_net+0x110/0x840 net/core/net_namespace.c:453
1 lock held by khungtaskd/1533:
#0: (tasklist_lock){.+.+}, at: [<ffffffff8702a1b9>] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4548
1 lock held by syz-executor.2/11891:
#0: (net_mutex){+.+.}, at: [<ffffffff85c22676>] copy_net_ns+0x156/0x440 net/core/net_namespace.c:413

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

NMI backtrace for cpu 0
CPU: 0 PID: 1533 Comm: khungtaskd Not tainted 4.14.299-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x1b2/0x281 lib/dump_stack.c:58
nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x13a/0x180 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline]
watchdog+0x5b9/0xb40 kernel/hung_task.c:274
kthread+0x30d/0x420 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:406
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 7942 Comm: kworker/u4:5 Not tainted 4.14.299-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Workqueue: krdsd rds_connect_worker
task: ffff8880b4e60400 task.stack: ffff88808d6f8000
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:779 [inline]
RIP: 0010:lock_release+0x41e/0x870 kernel/locking/lockdep.c:4020
RSP: 0018:ffff88808d6ffa90 EFLAGS: 00000286
RAX: 1ffffffff11e13d9 RBX: 1ffff11011adff55 RCX: 1ffff110169cc1a5
RDX: dffffc0000000000 RSI: 0000000000000005 RDI: 0000000000000286
RBP: ffff8880b4e60400 R08: ffffffff8b9a0888 R09: 0000000000000004
R10: 0000000000000000 R11: 0000000000000000 R12: 668ce214ba89aa69
R13: 0000000000000003 R14: ffff8880b4e60400 R15: 0000000000000005
FS: 0000000000000000(0000) GS:ffff8880ba500000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f3e5ff82018 CR3: 00000000a17dc000 CR4: 00000000003406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
__raw_spin_unlock_bh include/linux/spinlock_api_smp.h:174 [inline]
_raw_spin_unlock_bh+0x17/0x30 kernel/locking/spinlock.c:208
spin_unlock_bh include/linux/spinlock.h:362 [inline]
inet_csk_find_open_port net/ipv4/inet_connection_sock.c:226 [inline]
inet_csk_get_port+0x932/0xd00 net/ipv4/inet_connection_sock.c:344
inet_bind+0x547/0x960 net/ipv4/af_inet.c:506
rds_tcp_conn_path_connect+0x263/0x4d0 net/rds/tcp_connect.c:119
rds_connect_worker+0x143/0x1d0 net/rds/threads.c:165
process_one_work+0x793/0x14a0 kernel/workqueue.c:2117
worker_thread+0x5cc/0xff0 kernel/workqueue.c:2251
kthread+0x30d/0x420 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:406
Code: 85 84 08 00 00 00 00 00 00 48 c1 e8 03 80 3c 10 00 0f 85 88 03 00 00 48 83 3d 26 bd ae 07 00 0f 84 ba 01 00 00 48 8b 3c 24 57 9d <0f> 1f 44 00 00 48 b8 00 00 00 00 00 fc ff df 48 c7 04 03 00 00


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[syzbot]

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