Free memory is -13496kB above reserved
lowmemorykiller: Killing 'syz-executor.5' (14517) (tgid 14513), adj 1000,
   to free 45656kB on behalf of 'udevd' (13054) because
   cache 948kB is below limit 6144kB for oom_score_adj 0
   Free memory is -13496kB above reserved
INFO: task kworker/u4:3:2120 blocked for more than 140 seconds.
      Not tainted 4.9.141+ #23
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u4:3    D25144  2120      2 0x80000000
Workqueue: netns cleanup_net
 ffff8801d3cdaf80 0000000000000000 ffff8801cf9f5d80 ffff8801d8410000
 ffff8801db621018 ffff8801c7e5f8a8 ffffffff828075c2 0000000000000003
 ffff8801d3cdb830 ffffed003a79b705 00ff8801d3cdaf80 ffff8801db6218f0
Call Trace:
 [<ffffffff82808aef>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff828094a3>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3586
 [<ffffffff8280b51d>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<ffffffff8280b51d>] mutex_lock_nested+0x38d/0x900 kernel/locking/mutex.c:621
 [<ffffffff823412d7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
 [<ffffffff827ae60e>] ip6_tnl_exit_net+0x7e/0x5b0 net/ipv6/ip6_tunnel.c:2238
 [<ffffffff822e3d70>] ops_exit_list.isra.0+0xb0/0x160 net/core/net_namespace.c:136
 [<ffffffff822e6ad2>] cleanup_net+0x3f2/0x8b0 net/core/net_namespace.c:473
 [<ffffffff81131001>] process_one_work+0x831/0x15f0 kernel/workqueue.c:2092
 [<ffffffff81131e96>] worker_thread+0xd6/0x1140 kernel/workqueue.c:2226
 [<ffffffff81142c3d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff82817a5c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373

Showing all locks held in the system:
2 locks held by khungtaskd/24:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8131c0cc>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8131c0cc>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff813fe63f>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/2029:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff81d37362>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
4 locks held by kworker/u4:3/2120:
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff81130f0c>] process_one_work+0x73c/0x15f0 kernel/workqueue.c:2085
 #1:  (net_cleanup_work){+.+.+.}, at: [<ffffffff81130f44>] process_one_work+0x774/0x15f0 kernel/workqueue.c:2089
 #2:  (net_mutex){+.+.+.}, at: [<ffffffff822e681f>] cleanup_net+0x13f/0x8b0 net/core/net_namespace.c:439
 #3:  (rtnl_mutex){+.+.+.}, at: [<ffffffff823412d7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
3 locks held by kworker/0:2/2243:
 #0:  ("%s"("ipv6_addrconf")){.+.+..}, at: [<ffffffff81130f0c>] process_one_work+0x73c/0x15f0 kernel/workqueue.c:2085
 #1:  ((addr_chk_work).work){+.+...}, at: [<ffffffff81130f44>] process_one_work+0x774/0x15f0 kernel/workqueue.c:2089
 #2:  (rtnl_mutex){+.+.+.}, at: [<ffffffff823412d7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
2 locks held by syz-executor.0/18810:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&tty->atomic_write_lock){+.+.+.}, at: [<ffffffff81d1f7e1>] tty_write_lock+0x21/0x60 drivers/tty/tty_io.c:1107
2 locks held by syz-executor.4/20683:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&tty->atomic_write_lock){+.+.+.}, at: [<ffffffff81d1f7e1>] tty_write_lock+0x21/0x60 drivers/tty/tty_io.c:1107
3 locks held by kworker/0:3/7403:
 #0:  ("events"){.+.+.+}, at: [<ffffffff81130f0c>] process_one_work+0x73c/0x15f0 kernel/workqueue.c:2085
 #1:  ((linkwatch_work).work){+.+...}, at: [<ffffffff81130f44>] process_one_work+0x774/0x15f0 kernel/workqueue.c:2089
 #2:  (rtnl_mutex){+.+.+.}, at: [<ffffffff823412d7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
1 lock held by syz-executor.1/14566:
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff823412d7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
1 lock held by syz-executor.1/14576:
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff823412d7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
1 lock held by init/14595:
 #0:  (&type->i_mutex_dir_key#3){++++++}, at: [<ffffffff8152a634>] inode_lock_shared include/linux/fs.h:776 [inline]
 #0:  (&type->i_mutex_dir_key#3){++++++}, at: [<ffffffff8152a634>] lookup_slow+0x154/0x470 fs/namei.c:1645

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

NMI backtrace for cpu 0
CPU: 0 PID: 24 Comm: khungtaskd Not tainted 4.9.141+ #23
 ffff8801d9907d08 ffffffff81b42e79 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810983b0 ffff8801d9907d40
 ffffffff81b4df89 0000000000000000 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81b42e79>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81b42e79>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81b4df89>] nmi_cpu_backtrace.cold.0+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81b4df1c>] nmi_trigger_cpumask_backtrace+0x12c/0x151 lib/nmi_backtrace.c:60
 [<ffffffff810984b4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff8131c65d>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff8131c65d>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff8131c65d>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff8131c65d>] watchdog+0x6ad/0xa20 kernel/hung_task.c:239
 [<ffffffff81142c3d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff82817a5c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 14596 Comm: init Not tainted 4.9.141+ #23
task: ffff880156618000 task.stack: ffff8800b73d8000
RIP: 0010:[<ffffffff81207798>] 
c [<ffffffff81207798>] __lock_acquire+0x3e8/0x4a10 kernel/locking/lockdep.c:3290
RSP: 0000:ffff8800b73dea80  EFLAGS: 00000046
RAX: 0000000000000000 RBX: ffff880156618950 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff880156618974
RBP: ffff8800b73dec30 R08: 0000000000000001 R09: 0000000000000000
R10: ffff880156618000 R11: 1ffff1002acc3129 R12: 0000000000000075
R13: 0000000000000004 R14: ffff88015661889c R15: 0000000000000000
FS:  00007f037f34b7a0(0000) GS:ffff8801db700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0ada116f80 CR3: 00000000247ad000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff88015661889c
c 0000000000000000
c ffff8800b73dec50
c ffffffff81207a04
c
 ffff8801566188a0
c ffff880156618948
c ffffffff83c73d80
c ffff880156618900
c
 0000000000002b92
c ffff880156618940
c ffff8801566188a0
c ffff880156618948
c
Call Trace:
 [<ffffffff8120c8d0>] lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756
 [<ffffffff82816c26>] __raw_spin_lock include/linux/spinlock_api_smp.h:144 [inline]
 [<ffffffff82816c26>] _raw_spin_lock+0x36/0x50 kernel/locking/spinlock.c:151
 [<ffffffff8141a061>] spin_lock include/linux/spinlock.h:302 [inline]
 [<ffffffff8141a061>] task_lock include/linux/sched.h:3257 [inline]
 [<ffffffff8141a061>] find_lock_task_mm+0xf1/0x270 mm/oom_kill.c:115
 [<ffffffff821effdf>] lowmem_scan+0x34f/0xaf0 drivers/staging/android/lowmemorykiller.c:134
 [<ffffffff81449cc6>] do_shrink_slab mm/vmscan.c:398 [inline]
 [<ffffffff81449cc6>] shrink_slab.part.8+0x3c6/0xa00 mm/vmscan.c:501
 [<ffffffff814557fd>] shrink_slab mm/vmscan.c:465 [inline]
 [<ffffffff814557fd>] shrink_node+0x1ed/0x740 mm/vmscan.c:2602
 [<ffffffff814560c7>] shrink_zones mm/vmscan.c:2749 [inline]
 [<ffffffff814560c7>] do_try_to_free_pages mm/vmscan.c:2791 [inline]
 [<ffffffff814560c7>] try_to_free_pages+0x377/0xb80 mm/vmscan.c:3002
 [<ffffffff81428a01>] __perform_reclaim mm/page_alloc.c:3324 [inline]
 [<ffffffff81428a01>] __alloc_pages_direct_reclaim mm/page_alloc.c:3345 [inline]
 [<ffffffff81428a01>] __alloc_pages_slowpath mm/page_alloc.c:3697 [inline]
 [<ffffffff81428a01>] __alloc_pages_nodemask+0x981/0x1bd0 mm/page_alloc.c:3862
 [<ffffffff8140c164>] __alloc_pages include/linux/gfp.h:433 [inline]
 [<ffffffff8140c164>] __alloc_pages_node include/linux/gfp.h:446 [inline]
 [<ffffffff8140c164>] alloc_pages_node include/linux/gfp.h:460 [inline]
 [<ffffffff8140c164>] __page_cache_alloc include/linux/pagemap.h:208 [inline]
 [<ffffffff8140c164>] pagecache_get_page+0x244/0x710 mm/filemap.c:1237
 [<ffffffff815bda70>] find_or_create_page include/linux/pagemap.h:309 [inline]
 [<ffffffff815bda70>] grow_dev_page fs/buffer.c:1005 [inline]
 [<ffffffff815bda70>] grow_buffers fs/buffer.c:1078 [inline]
 [<ffffffff815bda70>] __getblk_slow fs/buffer.c:1105 [inline]
 [<ffffffff815bda70>] __getblk_gfp+0x240/0x700 fs/buffer.c:1386
 [<ffffffff815c09d9>] __getblk include/linux/buffer_head.h:373 [inline]
 [<ffffffff815c09d9>] __breadahead+0x79/0xf0 fs/buffer.c:1396
 [<ffffffff816c2111>] sb_breadahead include/linux/buffer_head.h:312 [inline]
 [<ffffffff816c2111>] __ext4_get_inode_loc+0x961/0xef0 fs/ext4/inode.c:4393
 [<ffffffff816cd5d7>] ext4_iget+0x1d7/0x3740 fs/ext4/inode.c:4540
 [<ffffffff816d0bc8>] ext4_iget_normal+0x88/0xd0 fs/ext4/inode.c:4777
 [<ffffffff816f7c22>] ext4_lookup+0x2f2/0x5e0 fs/ext4/namei.c:1575
 [<ffffffff8152a72a>] lookup_slow+0x24a/0x470 fs/namei.c:1668
 [<ffffffff81539cf2>] walk_component+0x822/0xcf0 fs/namei.c:1784
 [<ffffffff8153aa82>] link_path_walk+0x8c2/0x1230 fs/namei.c:2120
 [<ffffffff8153b6e4>] path_lookupat.isra.10+0x1b4/0x410 fs/namei.c:2282
 [<ffffffff8153f697>] filename_lookup.part.18+0x177/0x370 fs/namei.c:2317
 [<ffffffff8153fa53>] filename_lookup fs/namei.c:2310 [inline]
 [<ffffffff8153fa53>] user_path_at_empty+0x53/0x70 fs/namei.c:2578
 [<ffffffff81504470>] user_path_at include/linux/namei.h:55 [inline]
 [<ffffffff81504470>] SYSC_faccessat fs/open.c:395 [inline]
 [<ffffffff81504470>] SyS_faccessat+0x240/0x6e0 fs/open.c:363
 [<ffffffff81504932>] SYSC_access fs/open.c:443 [inline]
 [<ffffffff81504932>] SyS_access+0x22/0x30 fs/open.c:441
 [<ffffffff810056ef>] do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285
 [<ffffffff82817893>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
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