INFO: task syz-executor.3:17031 blocked for more than 140 seconds. Not tainted 4.9.180+ #3 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.3 D28552 17031 2120 0x00000004 0000000000000087 ffff8801c94a97c0 ffff8801cc522100 ffff8801db621000 ffff8801d6774740 ffff8801db621018 ffff8801d8647c08 ffffffff8280932e 0000000000000000 ffff8801c94a97c0 00ff8801d8647c38 ffff8801db6218f0 Call Trace: [<0000000093424ce6>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<0000000003b7da53>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<00000000389dd3a9>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<00000000389dd3a9>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<00000000644cd2a5>] copy_net_ns+0x15b/0x340 net/core/net_namespace.c:407 [<0000000064b7b213>] create_new_namespaces+0x37c/0x7a0 kernel/nsproxy.c:106 [<000000007d0ecc4b>] unshare_nsproxy_namespaces+0xab/0x1e0 kernel/nsproxy.c:205 [<00000000758c7dcf>] SYSC_unshare kernel/fork.c:2276 [inline] [<00000000758c7dcf>] SyS_unshare+0x305/0x6f0 kernel/fork.c:2226 [<0000000020c4c80b>] do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288 [<00000000983e97f3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb Showing all locks held in the system: 2 locks held by khungtaskd/24: #0: (rcu_read_lock){......}, at: [<00000000248a8646>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] #0: (rcu_read_lock){......}, at: [<00000000248a8646>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 #1: (tasklist_lock){.+.+..}, at: [<00000000e4367fb7>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4336 2 locks held by getty/2027: #0: (&tty->ldisc_sem){++++++}, at: [<00000000aeba14c8>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+...}, at: [<00000000de15c915>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 5 locks held by kworker/u4:6/2176: #0: ("%s""netns"){.+.+.+}, at: [<00000000e68db288>] process_one_work+0x790/0x1600 kernel/workqueue.c:2107 #1: (net_cleanup_work){+.+.+.}, at: [<000000002c902331>] process_one_work+0x7ce/0x1600 kernel/workqueue.c:2111 #2: (net_mutex){+.+.+.}, at: [<00000000a5b2d620>] cleanup_net+0x131/0x8a0 net/core/net_namespace.c:440 #3: (rtnl_mutex){+.+.+.}, at: [<000000004f302723>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70 #4: (cpu_hotplug.dep_map){++++++}, at: [<00000000c3489208>] get_online_cpus+0x32/0x90 kernel/cpu.c:254 1 lock held by syz-executor.3/17031: #0: (net_mutex){+.+.+.}, at: [<00000000644cd2a5>] copy_net_ns+0x15b/0x340 net/core/net_namespace.c:407 1 lock held by syz-executor.0/17034: #0: (net_mutex){+.+.+.}, at: [<00000000644cd2a5>] copy_net_ns+0x15b/0x340 net/core/net_namespace.c:407 1 lock held by syz-executor.0/17083: #0: (net_mutex){+.+.+.}, at: [<00000000644cd2a5>] copy_net_ns+0x15b/0x340 net/core/net_namespace.c:407 1 lock held by syz-executor.5/17036: #0: (net_mutex){+.+.+.}, at: [<00000000644cd2a5>] copy_net_ns+0x15b/0x340 net/core/net_namespace.c:407 1 lock held by syz-executor.4/17038: #0: (net_mutex){+.+.+.}, at: [<00000000644cd2a5>] copy_net_ns+0x15b/0x340 net/core/net_namespace.c:407 1 lock held by syz-executor.1/17042: #0: (net_mutex){+.+.+.}, at: [<00000000644cd2a5>] copy_net_ns+0x15b/0x340 net/core/net_namespace.c:407 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 24 Comm: khungtaskd Not tainted 4.9.180+ #3 ffff8801d98d7cc8 ffffffff81b577f1 0000000000000000 0000000000000000 0000000000000000 ffffffff81099901 dffffc0000000000 ffff8801d98d7d00 ffffffff81b62a8c 0000000000000000 0000000000000000 0000000000000000 Call Trace: [<000000009f9dba12>] __dump_stack lib/dump_stack.c:15 [inline] [<000000009f9dba12>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<00000000f082b884>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<000000000cddaa6b>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<000000004493c613>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<0000000056d60bda>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<0000000056d60bda>] check_hung_task kernel/hung_task.c:126 [inline] [<0000000056d60bda>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<0000000056d60bda>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<00000000dbe140f1>] kthread+0x278/0x310 kernel/kthread.c:211 [<00000000178441f9>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:375 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 17072 Comm: syz-executor.2 Not tainted 4.9.180+ #3 task: 00000000657c22d8 task.stack: 00000000ccc72fe7 RIP: 0033:[<00000000004018e4>] c [<00000000573b1eeb>] 0x4018e4 RSP: 002b:00007ff0ac245690 EFLAGS: 00000202 RAX: 000000001f1ee6f7 RBX: 000000000000000b RCX: 0000000000459279 RDX: 0000000000000000 RSI: 00007ff0ac2456c0 RDI: 000000000000000b RBP: 616c773070707028 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: e9ffffffffffff1b R13: 0000000000000000 R14: 0000000000000000 R15: 000000030000003d FS: 00007ff0ac246700(0000) GS:ffff8801db700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ff0ac203db8 CR3: 00000001c59e6000 CR4: 00000000001606b0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400