syzbot

INFO: task kworker/u4:3:2163 blocked for more than 140 seconds.
      Not tainted 4.4.174+ #4
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u4:3    D ffff88009c197968 25328  2163      2 0x80000000
Workqueue: netns cleanup_net
 ffff88009c197968 ffff8800b7c317c0 447e11b93d275917 ffff8800b7c317c0
 0000000000000002 ffff8800b7c32000 ffff8801db71f180 ffff8801db71f1a8
 ffff8801db71e898 ffff8801d3ad2f80 ffff8800b7c317c0 ffffed0013832001
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
 [<ffffffff8221a971>] cleanup_net+0x131/0x860 net/core/net_namespace.c:418
 [<ffffffff81122c25>] process_one_work+0x825/0x1720 kernel/workqueue.c:2064
 [<ffffffff81124004>] worker_thread+0x4e4/0xf50 kernel/workqueue.c:2196
 [<ffffffff811342c3>] kthread+0x273/0x310 kernel/kthread.c:211
 [<ffffffff82718fc5>] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:537
3 locks held by kworker/u4:3/2163:
 #0:  ("%s""netns"){.+.+..}, at: [<ffffffff81122b0a>] process_one_work+0x70a/0x1720 kernel/workqueue.c:2057
 #1:  (net_cleanup_work){+.+...}, at: [<ffffffff81122b42>] process_one_work+0x742/0x1720 kernel/workqueue.c:2061
 #2:  (net_mutex){+.+.+.}, at: [<ffffffff8221a971>] cleanup_net+0x131/0x860 net/core/net_namespace.c:418
Sending NMI to all CPUs:
NMI backtrace for cpu 0
CPU: 0 PID: 20 Comm: khungtaskd Not tainted 4.4.174+ #4
task: ffff8801da6c5f00 task.stack: ffff8800001c8000
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:ffff8800001cfc88  EFLAGS: 00000046
RAX: 0000000000000000 RBX: 0000000000000c00 RCX: 0000000000000000
RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fc300
RBP: ffff8800001cfcb8 R08: 0000000000000018 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000246
R13: 0000000003000000 R14: ffffffff82e5f2e0 R15: 0000000000000002
FS:  0000000000000000(0000) GS:ffff8801db600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000009ce0c000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 0000000000000001 ffffffff82e5f2e0 ffffffff831a6ac0 fffffbfff0634c34
 000000000001b6c0 0000000000000008 ffff8800001cfcd8 ffffffff81092bee
 0000000000000008 ffffffff82924260 ffff8800001cfd30 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 
NMI backtrace for cpu 1
CPU: 1 PID: 14277 Comm: syz-executor.0 Not tainted 4.4.174+ #4
task: ffff880084a18000 task.stack: ffff8801b1600000
RIP: 0010:[<ffffffff810bb30c>]  [<ffffffff810bb30c>] trace_tlb_flush include/trace/events/tlb.h:37 [inline]
RIP: 0010:[<ffffffff810bb30c>]  [<ffffffff810bb30c>] switch_mm_irqs_off+0x2dc/0xac0 arch/x86/mm/tlb.c:174
RSP: 0018:ffff8801b1607748  EFLAGS: 00000046
RAX: 0000000000000000 RBX: ffff8800b9301f80 RCX: 1ffffffff0634a0a
RDX: dffffc0000000000 RSI: ffffffff81b0abec RDI: ffffffff8292c000
RBP: ffff8801b1607780 R08: ffff880084a18438 R09: ffffffff831a5078
R10: ffff880084a18268 R11: 0000000000000001 R12: 0000000000000001
R13: ffff8801b412ef40 R14: 1ffffffff0506d10 R15: ffffffff831a5078
FS:  00007f62467dd700(0000) GS:ffff8801db700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000000b9122000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801db71f1b0 0000000000000003 ffff8801b412ef40 ffff8801db71e880
 ffff8800b9301f80 ffff880084a18498 0000000000000003 ffff8801b1607808
 ffffffff82708159 00007f6200000002 0000000000000000 ffff8801b1607b78
Call Trace:
 [<ffffffff82708159>] context_switch kernel/sched/core.c:2788 [inline]
 [<ffffffff82708159>] __schedule+0x709/0x1ee0 kernel/sched/core.c:3326
 [<ffffffff82709971>] preempt_schedule_common+0x41/0x70 kernel/sched/core.c:3396
 [<ffffffff827099c4>] preempt_schedule+0x24/0x30 kernel/sched/core.c:3421
 [<ffffffff810021b8>] ___preempt_schedule+0x12/0x14
 [<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
 [<ffffffff8148475f>] kasan_slab_alloc+0xf/0x20 mm/kasan/kasan.c:554
 [<ffffffff8147fe9c>] slab_post_alloc_hook mm/slub.c:1349 [inline]
 [<ffffffff8147fe9c>] slab_alloc_node mm/slub.c:2615 [inline]
 [<ffffffff8147fe9c>] slab_alloc mm/slub.c:2623 [inline]
 [<ffffffff8147fe9c>] kmem_cache_alloc+0xdc/0x2c0 mm/slub.c:2628
 [<ffffffff81b0bd8c>] kmem_cache_zalloc include/linux/slab.h:610 [inline]
 [<ffffffff81b0bd8c>] fill_pool lib/debugobjects.c:99 [inline]
 [<ffffffff81b0bd8c>] __debug_object_init+0x5bc/0x880 lib/debugobjects.c:315
 [<ffffffff81b0c066>] debug_object_init+0x16/0x20 lib/debugobjects.c:367
 [<ffffffff8123ac33>] rcuhead_fixup_activate kernel/rcu/update.c:381 [inline]
 [<ffffffff8123ac33>] rcuhead_fixup_activate+0x23/0x40 kernel/rcu/update.c:370
 [<ffffffff81b0c32a>] debug_object_fixup lib/debugobjects.c:279 [inline]
 [<ffffffff81b0c32a>] debug_object_activate+0x29a/0x470 lib/debugobjects.c:442
 [<ffffffff812446c5>] debug_rcu_head_queue kernel/rcu/rcu.h:75 [inline]
 [<ffffffff812446c5>] __call_rcu.constprop.0+0x35/0x930 kernel/rcu/tree.c:3059
 [<ffffffff81244fd2>] call_rcu+0x12/0x20 kernel/rcu/tree_plugin.h:662
 [<ffffffff81139dad>] __put_cred+0xcd/0x110 kernel/cred.c:149
 [<ffffffff8113a5af>] put_cred include/linux/cred.h:274 [inline]
 [<ffffffff8113a5af>] commit_creds+0x48f/0xa20 kernel/cred.c:487
 [<ffffffff8110c4a8>] SYSC_setuid kernel/sys.c:572 [inline]
 [<ffffffff8110c4a8>] SyS_setuid+0x2a8/0x400 kernel/sys.c:537
 [<ffffffff82718ba1>] entry_SYSCALL_64_fastpath+0x1e/0x9a
Cod