Free memory is -14664kB above reserved
lowmemorykiller: Killing 'syz-executor.1' (11839) (tgid 11839), adj 1000,
   to free 34976kB on behalf of 'syz-fuzzer' (2044) because
   cache 260kB is below limit 6144kB for oom_score_adj 0
   Free memory is -14660kB above reserved
INFO: task syz-executor.2:17106 blocked for more than 140 seconds.
      Not tainted 4.9.141+ #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.2  D28776 17106   2083 0x80000002
 ffff8801c94ddf00 0000000000000000 ffff8801d4b03c80 ffff8801d8410000
 ffff8801db721018 ffff88017b40f510 ffffffff828075c2 ffffffff83c27940
 0000000041b58ab3 ffffffff82e33920 00ffffff83c7a980 ffff8801db7218f0
Call Trace:
 [<ffffffff82808aef>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff828142d5>] schedule_timeout+0x735/0xe20 kernel/time/timer.c:1771
 [<ffffffff8280a63f>] do_wait_for_common kernel/sched/completion.c:75 [inline]
 [<ffffffff8280a63f>] __wait_for_common kernel/sched/completion.c:93 [inline]
 [<ffffffff8280a63f>] wait_for_common+0x3ef/0x5d0 kernel/sched/completion.c:101
 [<ffffffff8280a838>] wait_for_completion+0x18/0x20 kernel/sched/completion.c:122
 [<ffffffff81243b37>] __wait_rcu_gp+0x137/0x1b0 kernel/rcu/update.c:369
 [<ffffffff8124c21a>] synchronize_rcu.part.55+0xfa/0x110 kernel/rcu/tree_plugin.h:684
 [<ffffffff8124c257>] synchronize_rcu+0x27/0x90 kernel/rcu/tree_plugin.h:685
 [<ffffffff8156fb0e>] namespace_unlock+0xfe/0x120 fs/namespace.c:1440
 [<ffffffff81578c0b>] drop_collected_mounts+0x8b/0xa0 fs/namespace.c:1871
 [<ffffffff8157e877>] put_mnt_ns+0x47/0x60 fs/namespace.c:3320
 [<ffffffff81146ba4>] free_nsproxy+0x44/0x1d0 kernel/nsproxy.c:175
 [<ffffffff81146f98>] switch_task_namespaces+0x98/0xb0 kernel/nsproxy.c:228
 [<ffffffff81146fc7>] exit_task_namespaces+0x17/0x20 kernel/nsproxy.c:233
 [<ffffffff810e6c48>] do_exit+0x788/0x2a50 kernel/exit.c:832
 [<ffffffff810ed3a1>] do_group_exit+0x111/0x300 kernel/exit.c:937
 [<ffffffff8110eb61>] get_signal+0x4e1/0x1460 kernel/signal.c:2321
 [<ffffffff81052aa5>] do_signal+0x95/0x1b00 arch/x86/kernel/signal.c:807
 [<ffffffff81003e2e>] exit_to_usermode_loop+0x10e/0x150 arch/x86/entry/common.c:158
 [<ffffffff81005932>] prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
 [<ffffffff81005932>] syscall_return_slowpath arch/x86/entry/common.c:263 [inline]
 [<ffffffff81005932>] do_syscall_64+0x3e2/0x550 arch/x86/entry/common.c:290
 [<ffffffff82817893>] 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: [<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
1 lock held by rsyslogd/1899:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff8156cc7c>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/2027:
 #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
2 locks held by syz-executor.4/3644:
 #0:  (&sb->s_type->i_mutex_key#8){+.+.+.}, at: [<ffffffff8229bd8b>] inode_lock include/linux/fs.h:766 [inline]
 #0:  (&sb->s_type->i_mutex_key#8){+.+.+.}, at: [<ffffffff8229bd8b>] __sock_release+0x8b/0x260 net/socket.c:604
 #1:  (sk_lock-AF_PACKET){+.+.+.}, at: [<ffffffff827d136d>] lock_sock include/net/sock.h:1404 [inline]
 #1:  (sk_lock-AF_PACKET){+.+.+.}, at: [<ffffffff827d136d>] packet_release+0x4ad/0xb70 net/packet/af_packet.c:3029

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

NMI backtrace for cpu 1
CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.141+ #1
 ffff8801d9907d08 ffffffff81b42e79 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810983b0 ffff8801d9907d40
 ffffffff81b4df89 0000000000000001 0000000000000000 0000000000000002
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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 17231 Comm: syz-executor.3 Not tainted 4.9.141+ #1
task: ffff880198e017c0 task.stack: ffff8801c5228000
RIP: 0010:[<ffffffff81d6254b>] 
c [<ffffffff81d6254b>] io_serial_in+0x6b/0x90 drivers/tty/serial/8250/8250_port.c:414
RSP: 0000:ffff8801c522eee0  EFLAGS: 00000002
RAX: dffffc0000000000 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: ffffffff81d624f1 RDI: ffffffff84b5bb58
RBP: ffff8801c522eef0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff84b5bb20
R13: 0000000000000020 R14: fffffbfff096b7ab R15: fffffbfff096b76d
FS:  00007f851da54700(0000) GS:ffff8801db600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000405fb0 CR3: 00000001d79a5000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff84b5bb20
c 000000000000270d
c ffff8801c522ef40
c ffffffff81d64764
c
 ffffffff81b6cdd8
c ffffffff84b5bb68
c ffffffff84b5bd5a
c ffffffff84b5bb20
c
 0000000000000039
c ffffffff81d648b0
c dffffc0000000000
c 0000000000000039
c
Call Trace:
 [<ffffffff81d64764>] serial_in drivers/tty/serial/8250/8250.h:111 [inline]
 [<ffffffff81d64764>] wait_for_xmitr+0x94/0x1e0 drivers/tty/serial/8250/8250_port.c:1997
 [<ffffffff81d648cf>] serial8250_console_putchar+0x1f/0x60 drivers/tty/serial/8250/8250_port.c:3103
 [<ffffffff81d4cce9>] uart_console_write+0x59/0xf0 drivers/tty/serial/serial_core.c:1866
 [<ffffffff81d6fae8>] serial8250_console_write+0x528/0x820 drivers/tty/serial/8250/8250_port.c:3169
 [<ffffffff81d5d4ff>] univ8250_console_write+0x5f/0x70 drivers/tty/serial/8250/8250_core.c:594
 [<ffffffff8122387d>] call_console_drivers.isra.0.constprop.15+0x1ad/0x360 kernel/printk/printk.c:1594
 [<ffffffff812265af>] console_unlock+0x47f/0xb50 kernel/printk/printk.c:2454
 [<ffffffff812270c8>] vprintk_emit+0x448/0x790 kernel/printk/printk.c:1908
 [<ffffffff81227438>] vprintk+0x28/0x30 kernel/printk/printk.c:1918
 [<ffffffff8122745d>] vprintk_default+0x1d/0x30 kernel/printk/printk.c:1919
 [<ffffffff81402f9f>] vprintk_func kernel/printk/internal.h:36 [inline]
 [<ffffffff81402f9f>] printk+0xaf/0xd7 kernel/printk/printk.c:1980
 [<ffffffff8222d9e8>] lowmem_scan.cold.1+0x1f9/0x35b drivers/staging/android/lowmemorykiller.c:177
 [<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
 [<ffffffff814c9e8b>] __alloc_pages include/linux/gfp.h:433 [inline]
 [<ffffffff814c9e8b>] __alloc_pages_node include/linux/gfp.h:446 [inline]
 [<ffffffff814c9e8b>] alloc_pages_node include/linux/gfp.h:460 [inline]
 [<ffffffff814c9e8b>] __vmalloc_area_node mm/vmalloc.c:1644 [inline]
 [<ffffffff814c9e8b>] __vmalloc_node_range+0x25b/0x600 mm/vmalloc.c:1702
 [<ffffffff814ca71b>] __vmalloc_node mm/vmalloc.c:1745 [inline]
 [<ffffffff814ca71b>] __vmalloc_node_flags mm/vmalloc.c:1759 [inline]
 [<ffffffff814ca71b>] vmalloc+0x5b/0x70 mm/vmalloc.c:1774
 [<ffffffff82450e91>] xt_alloc_entry_offsets+0x41/0x60 net/netfilter/x_tables.c:758
 [<ffffffff82783c95>] translate_table+0x215/0x1690 net/ipv6/netfilter/ip6_tables.c:733
 [<ffffffff827873ee>] do_replace net/ipv6/netfilter/ip6_tables.c:1186 [inline]
 [<ffffffff827873ee>] do_ip6t_set_ctl+0x2ce/0x470 net/ipv6/netfilter/ip6_tables.c:1712
 [<ffffffff823e290d>] nf_sockopt net/netfilter/nf_sockopt.c:105 [inline]
 [<ffffffff823e290d>] nf_setsockopt+0x6d/0xc0 net/netfilter/nf_sockopt.c:114
 [<ffffffff826f53f8>] ipv6_setsockopt+0xc8/0x130 net/ipv6/ipv6_sockglue.c:922
 [<ffffffff824deaa8>] tcp_setsockopt+0x88/0xe0 net/ipv4/tcp.c:2758
 [<ffffffff822a747a>] sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:2706
 [<ffffffff822a4d76>] SYSC_setsockopt net/socket.c:1785 [inline]
 [<ffffffff822a4d76>] SyS_setsockopt+0x166/0x260 net/socket.c:1764
 [<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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c