INFO: task syz-executor.3:25156 blocked for more than 140 seconds.
      Not tainted 4.4.174+ #4
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.3  D ffff8801bc95f9d8 27856 25156  24854 0x00000000
 ffff8801bc95f9d8 ffff8801ae7d0000 857c14ed40fdbfca ffff8801ae7d0000
 0000000000000000 ffff8801ae7d0800 ffff8801db61f180 ffff8801db61f1a8
 ffff8801db61e898 ffff8800922117c0 ffff8801ae7d0000 ffffed003792b001
Call Trace:
 [<ffffffff82709b79>] schedule+0x99/0x1d0 kernel/sched/core.c:3355
 [<ffffffff8270a333>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3388
 [<ffffffff8270c492>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<ffffffff8270c492>] mutex_lock_nested+0x3c2/0xb80 kernel/locking/mutex.c:621
 [<ffffffff8221b16a>] copy_net_ns+0xca/0x250 net/core/net_namespace.c:387
 [<ffffffff81136a90>] create_new_namespaces+0x2f0/0x670 kernel/nsproxy.c:95
 [<ffffffff8113709a>] copy_namespaces+0x28a/0x320 kernel/nsproxy.c:150
 [<ffffffff810cd012>] copy_process+0x2472/0x68a0 kernel/fork.c:1522
 [<ffffffff810d186e>] _do_fork+0x14e/0xdc0 kernel/fork.c:1806
 [<ffffffff810d25b7>] SYSC_clone kernel/fork.c:1917 [inline]
 [<ffffffff810d25b7>] SyS_clone+0x37/0x50 kernel/fork.c:1911
 [<ffffffff82718cb7>] tracesys+0x88/0x8d
1 lock held by syz-executor.3/25156:
 #0:  (net_mutex){+.+.+.}, at: [<ffffffff8221b16a>] copy_net_ns+0xca/0x250 net/core/net_namespace.c:387
Sending NMI to all CPUs:
NMI backtrace for cpu 0
CPU: 0 PID: 25435 Comm: syz-executor.3 Not tainted 4.4.174+ #4
task: ffff8800a1104740 task.stack: ffff8801b4018000
RIP: 0010:[<ffffffff8115d344>]  [<ffffffff8115d344>] preempt_count_add+0x14/0x1d0 kernel/sched/core.c:3069
RSP: 0018:ffff8801b401f338  EFLAGS: 00000202
RAX: dffffc0000000000 RBX: ffff880084a28c10 RCX: 1ffffffff0634400
RDX: 0000000000000000 RSI: ffff880084a28c10 RDI: 0000000000000001
RBP: ffff8801b401f348 R08: ffff8801b401f488 R09: 0000000000000000
R10: ffff8801b401f9f0 R11: 0000000000000000 R12: 0000000000000001
R13: ffff8801b401f488 R14: ffff8801b401fff8 R15: ffff8801b4018000
FS:  0000000000000005(0063) GS:ffff8801db600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9e6e6cc000 CR3: 00000001ae8af000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff880084a28c10 ffff880084a28c10 ffff8801b401f360 ffffffff812aef73
 0000000000000000 ffff8801b401f378 ffffffff8112f548 ffff8801b401f990
 ffff8801b401f3d0 ffffffff81013549 ffff880084a28c10 ffff8801b401f9f0
Call Trace:
 [<ffffffff812aef73>] is_module_text_address+0x13/0x50 kernel/module.c:4107
 [<ffffffff8112f548>] __kernel_text_address+0x68/0xa0 kernel/extable.c:103
 [<ffffffff81013549>] print_context_stack+0x59/0xd0 arch/x86/kernel/dumpstack.c:107
 [<ffffffff81012bb9>] dump_trace+0x179/0x390 arch/x86/kernel/dumpstack_64.c:243
 [<ffffffff8102e3c6>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff81483f22>] save_stack mm/kasan/kasan.c:512 [inline]
 [<ffffffff81483f22>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff81483f22>] kasan_kmalloc.part.0+0x62/0xf0 mm/kasan/kasan.c:616
 [<ffffffff81484197>] kasan_kmalloc+0xb7/0xd0 mm/kasan/kasan.c:601
 [<ffffffff81484a40>] kasan_krealloc+0x60/0x80 mm/kasan/kasan.c:654
 [<ffffffff8147c8fa>] ksize+0x8a/0xf0 mm/slub.c:3727
 [<ffffffff821f7b69>] __alloc_skb+0x139/0x5d0 net/core/skbuff.c:237
 [<ffffffff81ab5f52>] alloc_skb include/linux/skbuff.h:820 [inline]
 [<ffffffff81ab5f52>] kobject_uevent_env+0x582/0xba0 lib/kobject_uevent.c:300
 [<ffffffff81ab6590>] kobject_uevent+0x20/0x30 lib/kobject_uevent.c:374
 [<ffffffff8229431c>] netdev_queue_add_kobject net/core/net-sysfs.c:1296 [inline]
 [<ffffffff8229431c>] netdev_queue_update_kobjects+0x1bc/0x290 net/core/net-sysfs.c:1314
 [<ffffffff8229473b>] register_queue_kobjects net/core/net-sysfs.c:1354 [inline]
 [<ffffffff8229473b>] netdev_register_kobject+0x23b/0x300 net/core/net-sysfs.c:1553
 [<ffffffff8224b059>] register_netdevice+0x669/0xcc0 net/core/dev.c:6807
 [<ffffffff8224b6cb>] register_netdev+0x1b/0x30 net/core/dev.c:6919
 [<ffffffff826a527e>] sit_init_net+0x2de/0x850 net/ipv6/sit.c:1833
 [<ffffffff82217370>] ops_init+0xb0/0x3a0 net/core/net_namespace.c:109
 [<ffffffff82219494>] setup_net+0x1b4/0x4e0 net/core/net_namespace.c:289
 [<ffffffff8221b175>] copy_net_ns+0xd5/0x250 net/core/net_namespace.c:388
NMI backtrace for cpu 1
CPU: 1 PID: 20 Comm: khungtaskd Not tainted 4.4.174+ #4
task: ffff8801da6f4740 task.stack: ffff8800001d0000
RIP: 0010:[<ffffffff8109b617>]  [<ffffffff8109b617>] _flat_send_IPI_mask arch/x86/kernel/apic/apic_flat_64.c:62 [inline]
RIP: 0010:[<ffffffff8109b617>]  [<ffffffff8109b617>] flat_send_IPI_mask+0xf7/0x1b0 arch/x86/kernel/apic/apic_flat_64.c:69
RSP: 0018:ffff8800001d7c88  EFLAGS: 00000046
RAX: 0000000000000000 RBX: 0000000000000c00 RCX: 0000000000000000
RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fc300
RBP: ffff8800001d7cb8 R08: 0000000000000018 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000246
R13: 0000000003000000 R14: ffffffff82e5f2e0 R15: 0000000000000002
FS:  0000000000000000(0000) GS:ffff8801db700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000001d71c9000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Stack:
 0000000000000001 ffffffff82e5f2e0 ffffffff831a6ac0 fffffbfff0634c34
 000000000001b6c0 0000000000000008 ffff8800001d7cd8 ffffffff81092bee
 0000000000000008 ffffffff82924260 ffff8800001d7d30 ffffffff81ab8252
Call Trace:
 [<ffffffff81092bee>] nmi_raise_cpu_backtrace+0x5e/0x80 arch/x86/kernel/apic/hw_nmi.c:33
 [<ffffffff81ab8252>] nmi_trigger_all_cpu_backtrace.cold+0xa1/0xae lib/nmi_backtrace.c:85
 [<ffffffff81092ca4>] arch_trigger_all_cpu_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 [<ffffffff813b4762>] trigger_all_cpu_backtrace include/linux/nmi.h:44 [inline]
 [<ffffffff813b4762>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff813b4762>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff813b4762>] watchdog.cold+0xd3/0xee kernel/hung_task.c:238
 [<ffffffff811342c3>] kthread+0x273/0x310 kernel/kthread.c:211
 [<ffffffff82718fc5>] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:537
Code: 00 c3 5f ff 80 e6 10 75 e1 41 c1 e5 18 44 89 2c 25 10 c3 5f ff 44 89 fa 09 da 80 cf 04 41 83 ff 02 0f 44 d3 89 14 25 00 c3 5f ff <41> f7 c4 00 02 00 00 75 1e 4c 89 e7 57 9d 0f 1f 44 00 00 e8 f1