Received-SPF: pass (google.com: domain of linux-wireless-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Mon, 4 Oct 2021 07:41:57 -0700
From:   Jakub Kicinski <kuba@kernel.org>
To:     syzbot <syzbot+7b4a6fc3e452c67173e0@syzkaller.appspotmail.com>
Cc:     davem@davemloft.net, johannes@sipsolutions.net,
        linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org,
        netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com,
        Florian Westphal <fw@strlen.de>
Subject: Re: [syzbot] INFO: task hung in reg_check_chans_work (3)
Message-ID: <20211004074157.1ba82e65@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
In-Reply-To: <000000000000035e6905cd5e1c91@google.com>
References: <000000000000035e6905cd5e1c91@google.com>
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netfilter... rtnl.. workqueue... let's CC Florian..

On Sat, 02 Oct 2021 05:49:24 -0700 syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    a4e6f95a891a Merge tag 'pinctrl-v5.15-2' of git://git.kern..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=102b4c03300000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=c76f0f4ac6e9f8d2
> dashboard link: https://syzkaller.appspot.com/bug?extid=7b4a6fc3e452c67173e0
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> 
> Unfortunately, I don't have any reproducer for this issue yet.
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+7b4a6fc3e452c67173e0@syzkaller.appspotmail.com
> 
> INFO: task kworker/0:10:10115 blocked for more than 143 seconds.
>       Not tainted 5.15.0-rc3-syzkaller #0
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:kworker/0:10    state:D stack:26216 pid:10115 ppid:     2 flags:0x00004000
> Workqueue: events_power_efficient reg_check_chans_work
> Call Trace:
>  context_switch kernel/sched/core.c:4940 [inline]
>  __schedule+0x940/0x26f0 kernel/sched/core.c:6287
>  schedule+0xd3/0x270 kernel/sched/core.c:6366
>  schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6425
>  __mutex_lock_common kernel/locking/mutex.c:669 [inline]
>  __mutex_lock+0xa34/0x12f0 kernel/locking/mutex.c:729
>  reg_check_chans_work+0x83/0xe10 net/wireless/reg.c:2423
>  process_one_work+0x9bf/0x16b0 kernel/workqueue.c:2297
>  worker_thread+0x658/0x11f0 kernel/workqueue.c:2444
>  kthread+0x3e5/0x4d0 kernel/kthread.c:319
>  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
> INFO: task syz-executor.0:17047 blocked for more than 143 seconds.
>       Not tainted 5.15.0-rc3-syzkaller #0
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:syz-executor.0  state:D stack:27152 pid:17047 ppid: 13518 flags:0x00004004
> Call Trace:
>  context_switch kernel/sched/core.c:4940 [inline]
>  __schedule+0x940/0x26f0 kernel/sched/core.c:6287
>  schedule+0xd3/0x270 kernel/sched/core.c:6366
>  schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6425
>  __mutex_lock_common kernel/locking/mutex.c:669 [inline]
>  __mutex_lock+0xa34/0x12f0 kernel/locking/mutex.c:729
>  rtnl_lock net/core/rtnetlink.c:72 [inline]
>  rtnetlink_rcv_msg+0x3be/0xb80 net/core/rtnetlink.c:5569
>  netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2504
>  netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
>  netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1340
>  netlink_sendmsg+0x86d/0xdb0 net/netlink/af_netlink.c:1929
>  sock_sendmsg_nosec net/socket.c:704 [inline]
>  sock_sendmsg+0xcf/0x120 net/socket.c:724
>  ____sys_sendmsg+0x6e8/0x810 net/socket.c:2409
>  ___sys_sendmsg+0xf3/0x170 net/socket.c:2463
>  __sys_sendmsg+0xe5/0x1b0 net/socket.c:2492
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x7f36146d1709
> RSP: 002b:00007f3611c48188 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
> RAX: ffffffffffffffda RBX: 00007f36147d5f60 RCX: 00007f36146d1709
> RDX: 0000000000000000 RSI: 0000000020000140 RDI: 0000000000000004
> RBP: 00007f361472bcb4 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007fff97d291cf R14: 00007f3611c48300 R15: 0000000000022000
> INFO: task syz-executor.4:17052 blocked for more than 143 seconds.
>       Not tainted 5.15.0-rc3-syzkaller #0
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:syz-executor.4  state:D stack:27216 pid:17052 ppid:  6665 flags:0x00004004
> Call Trace:
>  context_switch kernel/sched/core.c:4940 [inline]
>  __schedule+0x940/0x26f0 kernel/sched/core.c:6287
>  schedule+0xd3/0x270 kernel/sched/core.c:6366
>  schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6425
>  __mutex_lock_common kernel/locking/mutex.c:669 [inline]
>  __mutex_lock+0xa34/0x12f0 kernel/locking/mutex.c:729
>  rtnl_lock net/core/rtnetlink.c:72 [inline]
>  rtnetlink_rcv_msg+0x3be/0xb80 net/core/rtnetlink.c:5569
>  netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2504
>  netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
>  netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1340
>  netlink_sendmsg+0x86d/0xdb0 net/netlink/af_netlink.c:1929
>  sock_sendmsg_nosec net/socket.c:704 [inline]
>  sock_sendmsg+0xcf/0x120 net/socket.c:724
>  ____sys_sendmsg+0x6e8/0x810 net/socket.c:2409
>  ___sys_sendmsg+0xf3/0x170 net/socket.c:2463
>  __sys_sendmsg+0xe5/0x1b0 net/socket.c:2492
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x7fb590d66709
> RSP: 002b:00007fb58e2dd188 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
> RAX: ffffffffffffffda RBX: 00007fb590e6af60 RCX: 00007fb590d66709
> RDX: 0000000000000000 RSI: 0000000020000140 RDI: 0000000000000004
> RBP: 00007fb590dc0cb4 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007ffd316687cf R14: 00007fb58e2dd300 R15: 0000000000022000
> INFO: task syz-executor.5:17058 blocked for more than 144 seconds.
>       Not tainted 5.15.0-rc3-syzkaller #0
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:syz-executor.5  state:D stack:28072 pid:17058 ppid:     1 flags:0x00000004
> Call Trace:
>  context_switch kernel/sched/core.c:4940 [inline]
>  __schedule+0x940/0x26f0 kernel/sched/core.c:6287
>  schedule+0xd3/0x270 kernel/sched/core.c:6366
>  schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6425
>  __mutex_lock_common kernel/locking/mutex.c:669 [inline]
>  __mutex_lock+0xa34/0x12f0 kernel/locking/mutex.c:729
>  rtnl_lock net/core/rtnetlink.c:72 [inline]
>  rtnetlink_rcv_msg+0x3be/0xb80 net/core/rtnetlink.c:5569
>  netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2504
>  netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
>  netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1340
>  netlink_sendmsg+0x86d/0xdb0 net/netlink/af_netlink.c:1929
>  sock_sendmsg_nosec net/socket.c:704 [inline]
>  sock_sendmsg+0xcf/0x120 net/socket.c:724
>  __sys_sendto+0x21c/0x320 net/socket.c:2036
>  __do_sys_sendto net/socket.c:2048 [inline]
>  __se_sys_sendto net/socket.c:2044 [inline]
>  __x64_sys_sendto+0xdd/0x1b0 net/socket.c:2044
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x7f8ff50a869c
> RSP: 002b:00007fffcb4bf570 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
> RAX: ffffffffffffffda RBX: 00007f8ff6132320 RCX: 00007f8ff50a869c
> RDX: 0000000000000028 RSI: 00007f8ff6132370 RDI: 0000000000000003
> RBP: 0000000000000000 R08: 00007fffcb4bf5c4 R09: 000000000000000c
> R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
> R13: 00007f8ff6132370 R14: 0000000000000003 R15: 0000000000000000
> 
> Showing all locks held in the system:
> 1 lock held by khungtaskd/27:
>  #0: ffffffff8b97d420 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6446
> 1 lock held by in:imklog/6230:
>  #0: ffff88801b8e9630 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:990
> 3 locks held by kworker/0:10/10115:
>  #0: ffff888010c73d38 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff888010c73d38 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: arch_atomic_long_set include/linux/atomic/atomic-long.h:41 [inline]
>  #0: ffff888010c73d38 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: atomic_long_set include/linux/atomic/atomic-instrumented.h:1198 [inline]
>  #0: ffff888010c73d38 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:634 [inline]
>  #0: ffff888010c73d38 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:661 [inline]
>  #0: ffff888010c73d38 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_one_work+0x8a3/0x16b0 kernel/workqueue.c:2268
>  #1: ffffc9000484fdb0 ((reg_check_chans).work){+.+.}-{0:0}, at: process_one_work+0x8d7/0x16b0 kernel/workqueue.c:2272
>  #2: ffffffff8d0e20a8 (rtnl_mutex){+.+.}-{3:3}, at: reg_check_chans_work+0x83/0xe10 net/wireless/reg.c:2423
> 6 locks held by kworker/u4:7/10365:
>  #0: ffff888140275938 ((wq_completion)netns){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff888140275938 ((wq_completion)netns){+.+.}-{0:0}, at: arch_atomic_long_set include/linux/atomic/atomic-long.h:41 [inline]
>  #0: ffff888140275938 ((wq_completion)netns){+.+.}-{0:0}, at: atomic_long_set include/linux/atomic/atomic-instrumented.h:1198 [inline]
>  #0: ffff888140275938 ((wq_completion)netns){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:634 [inline]
>  #0: ffff888140275938 ((wq_completion)netns){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:661 [inline]
>  #0: ffff888140275938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x8a3/0x16b0 kernel/workqueue.c:2268
>  #1: ffffc9000770fdb0 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x8d7/0x16b0 kernel/workqueue.c:2272
>  #2: ffffffff8d0cee50 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x9b/0xb00 net/core/net_namespace.c:553
>  #3: ffffffff8d10de08 (devlink_mutex){+.+.}-{3:3}, at: devlink_pernet_pre_exit+0x84/0x3b0 net/core/devlink.c:11533
>  #4: ffff88807c8f7658 (&nsim_bus_dev->nsim_bus_reload_lock){+.+.}-{3:3}, at: nsim_dev_reload_up+0xb3/0x7b0 drivers/net/netdevsim/dev.c:897
>  #5: ffffffff8d0e20a8 (rtnl_mutex){+.+.}-{3:3}, at: devlink_nl_port_fill+0x17a/0x16a0 net/core/devlink.c:995
> 3 locks held by kworker/1:13/13828:
>  #0: ffff888010c67d38 ((wq_completion)events){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff888010c67d38 ((wq_completion)events){+.+.}-{0:0}, at: arch_atomic_long_set include/linux/atomic/atomic-long.h:41 [inline]
>  #0: ffff888010c67d38 ((wq_completion)events){+.+.}-{0:0}, at: atomic_long_set include/linux/atomic/atomic-instrumented.h:1198 [inline]
>  #0: ffff888010c67d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:634 [inline]
>  #0: ffff888010c67d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:661 [inline]
>  #0: ffff888010c67d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x8a3/0x16b0 kernel/workqueue.c:2268
>  #1: ffffc90003fa7db0 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x8d7/0x16b0 kernel/workqueue.c:2272
>  #2: ffffffff8d0e20a8 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xb/0x60 net/core/link_watch.c:251
> 3 locks held by kworker/1:15/13832:
>  #0: ffff888010c67d38 ((wq_completion)events){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff888010c67d38 ((wq_completion)events){+.+.}-{0:0}, at: arch_atomic_long_set include/linux/atomic/atomic-long.h:41 [inline]
>  #0: ffff888010c67d38 ((wq_completion)events){+.+.}-{0:0}, at: atomic_long_set include/linux/atomic/atomic-instrumented.h:1198 [inline]
>  #0: ffff888010c67d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:634 [inline]
>  #0: ffff888010c67d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:661 [inline]
>  #0: ffff888010c67d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x8a3/0x16b0 kernel/workqueue.c:2268
>  #1: ffffc90002c07db0 (deferred_process_work){+.+.}-{0:0}, at: process_one_work+0x8d7/0x16b0 kernel/workqueue.c:2272
>  #2: ffffffff8d0e20a8 (rtnl_mutex){+.+.}-{3:3}, at: switchdev_deferred_process_work+0xa/0x20 net/switchdev/switchdev.c:74
> 3 locks held by kworker/u4:9/14752:
>  #0: ffff88801871b138 ((wq_completion)cfg80211){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff88801871b138 ((wq_completion)cfg80211){+.+.}-{0:0}, at: arch_atomic_long_set include/linux/atomic/atomic-long.h:41 [inline]
>  #0: ffff88801871b138 ((wq_completion)cfg80211){+.+.}-{0:0}, at: atomic_long_set include/linux/atomic/atomic-instrumented.h:1198 [inline]
>  #0: ffff88801871b138 ((wq_completion)cfg80211){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:634 [inline]
>  #0: ffff88801871b138 ((wq_completion)cfg80211){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:661 [inline]
>  #0: ffff88801871b138 ((wq_completion)cfg80211){+.+.}-{0:0}, at: process_one_work+0x8a3/0x16b0 kernel/workqueue.c:2268
>  #1: ffffc9001062fdb0 ((work_completion)(&(&rdev->dfs_update_channels_wk)->work)){+.+.}-{0:0}, at: process_one_work+0x8d7/0x16b0 kernel/workqueue.c:2272
>  #2: ffffffff8d0e20a8 (rtnl_mutex){+.+.}-{3:3}, at: cfg80211_dfs_channels_update_work+0x91/0x5f0 net/wireless/mlme.c:842
> 2 locks held by kworker/0:21/15633:
> 3 locks held by kworker/0:23/15637:
>  #0: ffff888027a5c538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff888027a5c538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: arch_atomic_long_set include/linux/atomic/atomic-long.h:41 [inline]
>  #0: ffff888027a5c538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: atomic_long_set include/linux/atomic/atomic-instrumented.h:1198 [inline]
>  #0: ffff888027a5c538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:634 [inline]
>  #0: ffff888027a5c538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:661 [inline]
>  #0: ffff888027a5c538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x8a3/0x16b0 kernel/workqueue.c:2268
>  #1: ffffc9000ad37db0 ((addr_chk_work).work){+.+.}-{0:0}, at: process_one_work+0x8d7/0x16b0 kernel/workqueue.c:2272
>  #2: ffffffff8d0e20a8 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_verify_work+0xa/0x20 net/ipv6/addrconf.c:4590
> 1 lock held by syz-executor.3/17036:
>  #0: ffffffff8d0e20a8 (rtnl_mutex){+.+.}-{3:3}, at: tun_detach drivers/net/tun.c:684 [inline]
>  #0: ffffffff8d0e20a8 (rtnl_mutex){+.+.}-{3:3}, at: tun_chr_close+0x3a/0x180 drivers/net/tun.c:3397
> 1 lock held by syz-executor.1/17042:
>  #0: ffffffff8d0e20a8 (rtnl_mutex){+.+.}-{3:3}, at: tun_detach drivers/net/tun.c:684 [inline]
>  #0: ffffffff8d0e20a8 (rtnl_mutex){+.+.}-{3:3}, at: tun_chr_close+0x3a/0x180 drivers/net/tun.c:3397
> 2 locks held by syz-executor.2/17046:
>  #0: ffffffff8d0e20a8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
>  #0: ffffffff8d0e20a8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x3be/0xb80 net/core/rtnetlink.c:5569
>  #1: ffffffff8b9867a8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:290 [inline]
>  #1: ffffffff8b9867a8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x4fc/0x620 kernel/rcu/tree_exp.h:837
> 1 lock held by syz-executor.0/17047:
>  #0: ffffffff8d0e20a8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
>  #0: ffffffff8d0e20a8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x3be/0xb80 net/core/rtnetlink.c:5569
> 1 lock held by syz-executor.4/17052:
>  #0: ffffffff8d0e20a8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
>  #0: ffffffff8d0e20a8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x3be/0xb80 net/core/rtnetlink.c:5569
> 1 lock held by syz-executor.5/17058:
>  #0: ffffffff8d0e20a8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
>  #0: ffffffff8d0e20a8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x3be/0xb80 net/core/rtnetlink.c:5569
> 1 lock held by systemd-udevd/17071:
>  #0: ffffffff8d0e20a8 (rtnl_mutex){+.+.}-{3:3}, at: dev_ioctl+0x470/0xee0 net/core/dev_ioctl.c:521
> 1 lock held by systemd-udevd/17072:
>  #0: ffffffff8d0e20a8 (rtnl_mutex){+.+.}-{3:3}, at: dev_ioctl+0x470/0xee0 net/core/dev_ioctl.c:521
> 
> =============================================
> 
> NMI backtrace for cpu 1
> CPU: 1 PID: 27 Comm: khungtaskd Not tainted 5.15.0-rc3-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:88 [inline]
>  dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
>  nmi_cpu_backtrace.cold+0x47/0x144 lib/nmi_backtrace.c:105
>  nmi_trigger_cpumask_backtrace+0x1ae/0x220 lib/nmi_backtrace.c:62
>  trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
>  check_hung_uninterruptible_tasks kernel/hung_task.c:210 [inline]
>  watchdog+0xc1d/0xf50 kernel/hung_task.c:295
>  kthread+0x3e5/0x4d0 kernel/kthread.c:319
>  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
> Sending NMI from CPU 1 to CPUs 0:
> NMI backtrace for cpu 0
> CPU: 0 PID: 17046 Comm: syz-executor.2 Not tainted 5.15.0-rc3-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> RIP: 0010:lockdep_enabled kernel/locking/lockdep.c:88 [inline]
> RIP: 0010:lockdep_softirqs_on+0x53/0x340 kernel/locking/lockdep.c:4398
> Code: 65 48 8b 1c 25 40 f0 01 00 38 d0 7c 08 84 d2 0f 85 2a 02 00 00 8b 3d 08 a4 13 0c 85 ff 0f 84 e7 01 00 00 65 8b 05 8d 4c a7 7e <85> c0 0f 85 d8 01 00 00 65 48 8b 2c 25 40 f0 01 00 48 8d bd f4 09
> RSP: 0018:ffffc900068f6bc0 EFLAGS: 00000002
> RAX: 0000000000000000 RBX: ffff888075086340 RCX: 1ffffffff1adca3d
> RDX: 0000000000000000 RSI: ffffffff814586b3 RDI: 0000000000000001
> RBP: ffffffff8761e7d3 R08: 0000000000000000 R09: ffffffff8b666843
> R10: ffffffff817b579d R11: 0000000000000000 R12: ffffffff8761e7d3
> R13: 0000000000006872 R14: 0000000000000000 R15: 0000000000000001
> FS:  00007f799a824700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f78595f8000 CR3: 00000000782ab000 CR4: 00000000003506f0
> Call Trace:
>  __local_bh_enable_ip+0xcd/0x120 kernel/softirq.c:371
>  local_bh_enable include/linux/bottom_half.h:32 [inline]
>  get_next_corpse net/netfilter/nf_conntrack_core.c:2252 [inline]
>  nf_ct_iterate_cleanup+0x15a/0x450 net/netfilter/nf_conntrack_core.c:2275
>  nf_ct_iterate_cleanup_net net/netfilter/nf_conntrack_core.c:2363 [inline]
>  nf_ct_iterate_cleanup_net+0x236/0x400 net/netfilter/nf_conntrack_core.c:2347
>  masq_device_event+0xae/0xe0 net/netfilter/nf_nat_masquerade.c:88
>  notifier_call_chain+0xb5/0x200 kernel/notifier.c:83
>  call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:1996
>  call_netdevice_notifiers_extack net/core/dev.c:2008 [inline]
>  call_netdevice_notifiers net/core/dev.c:2022 [inline]
>  __dev_notify_flags+0x1da/0x2b0 net/core/dev.c:8801
>  dev_change_flags+0x112/0x170 net/core/dev.c:8837
>  do_setlink+0x96d/0x3970 net/core/rtnetlink.c:2719
>  rtnl_group_changelink net/core/rtnetlink.c:3242 [inline]
>  __rtnl_newlink+0xc06/0x1750 net/core/rtnetlink.c:3396
>  rtnl_newlink+0x64/0xa0 net/core/rtnetlink.c:3506
>  rtnetlink_rcv_msg+0x413/0xb80 net/core/rtnetlink.c:5572
>  netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2504
>  netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
>  netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1340
>  netlink_sendmsg+0x86d/0xdb0 net/netlink/af_netlink.c:1929
>  sock_sendmsg_nosec net/socket.c:704 [inline]
>  sock_sendmsg+0xcf/0x120 net/socket.c:724
>  ____sys_sendmsg+0x6e8/0x810 net/socket.c:2409
>  ___sys_sendmsg+0xf3/0x170 net/socket.c:2463
>  __sys_sendmsg+0xe5/0x1b0 net/socket.c:2492
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x7f799d2ad709
> Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007f799a824188 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
> RAX: ffffffffffffffda RBX: 00007f799d3b1f60 RCX: 00007f799d2ad709
> RDX: 0000000000000000 RSI: 0000000020000140 RDI: 0000000000000004
> RBP: 00007f799d307cb4 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007fff88eac50f R14: 00007f799a824300 R15: 0000000000022000
> ----------------
> Code disassembly (best guess):
>    0:	65 48 8b 1c 25 40 f0 	mov    %gs:0x1f040,%rbx
>    7:	01 00
>    9:	38 d0                	cmp    %dl,%al
>    b:	7c 08                	jl     0x15
>    d:	84 d2                	test   %dl,%dl
>    f:	0f 85 2a 02 00 00    	jne    0x23f
>   15:	8b 3d 08 a4 13 0c    	mov    0xc13a408(%rip),%edi        # 0xc13a423
>   1b:	85 ff                	test   %edi,%edi
>   1d:	0f 84 e7 01 00 00    	je     0x20a
>   23:	65 8b 05 8d 4c a7 7e 	mov    %gs:0x7ea74c8d(%rip),%eax        # 0x7ea74cb7
> * 2a:	85 c0                	test   %eax,%eax <-- trapping instruction
>   2c:	0f 85 d8 01 00 00    	jne    0x20a
>   32:	65 48 8b 2c 25 40 f0 	mov    %gs:0x1f040,%rbp
>   39:	01 00
>   3b:	48                   	rex.W
>   3c:	8d                   	.byte 0x8d
>   3d:	bd                   	.byte 0xbd
>   3e:	f4                   	hlt
>   3f:	09                   	.byte 0x9
> 
> 
> ---
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