syzbot

lowmemorykiller: Killing 'syz-executor.1' (12155) (tgid 12137), adj 1000,
   to free 51384kB on behalf of 'syz-executor.3' (12174) because
   cache 144kB is below limit 6144kB for oom_score_adj 0
   Free memory is -1200kB above reserved
INFO: task syz-executor.1:12155 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.1  D
lowmemorykiller: Killing 'syz-executor.1' (12155) (tgid 12137), adj 1000,
   to free 51384kB on behalf of 'rsyslogd' (1905) because
   cache 144kB is below limit 6144kB for oom_score_adj 0
   Free memory is -1200kB above reserved
lowmemorykiller: Killing 'syz-executor.1' (12155) (tgid 12137), adj 1000,
   to free 51384kB on behalf of 'syz-executor.5' (12150) because
   cache 144kB is below limit 6144kB for oom_score_adj 0
   Free memory is -1200kB above reserved
 ffff8801b7d879d8 28824 12155   2102 0x00100004
 ffff8801b7d879d8 ffff8801a8a85f00 f0ddf3ffa9614549 ffff8801a8a85f00
 0000000000000000 ffff8801a8a86700 ffff8801db71f180 ffff8801db71f1a8
 ffff8801db71e898 ffff88006bd54740 ffff8801a8a85f00 ffffed0036fb0001
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.1/12155:
 #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: 1905 Comm: rsyslogd Not tainted 4.4.174+ #4
task: ffff8800b9088000 task.stack: ffff8801d6d78000
RIP: 0010:[<ffffffff81cc252b>]  [<ffffffff81cc252b>] io_serial_in+0x6b/0x90 drivers/tty/serial/8250/8250_port.c:399
RSP: 0018:ffff8801d6d7f278  EFLAGS: 00000002
RAX: dffffc0000000000 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: ffffffff81cc24d1 RDI: ffffffff8496e518
RBP: ffff8801d6d7f288 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: ffffffff83fdf267 R12: ffffffff8496e4e0
R13: 0000000000000020 R14: fffffbfff092dce3 R15: fffffbfff092dca5
FS:  00007f7284f52700(0000) GS:ffff8801db600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000019ff1f8 CR3: 00000001d9891000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Stack:
 ffffffff8496e4e0 0000000000002710 ffff8801d6d7f2d8 ffffffff81cc461f
 ffffed003adafe71 ffffffff8496e528 ffffffff8496e71a ffffffff83fdf16e
 ffffffff8496e4e0 0000000000000065 dffffc0000000000 0000000000000065
Call Trace:
 [<ffffffff81cc461f>] serial_in drivers/tty/serial/8250/8250.h:97 [inline]
 [<ffffffff81cc461f>] wait_for_xmitr+0x8f/0x1e0 drivers/tty/serial/8250/8250_port.c:1717
 [<ffffffff81cc4790>] serial8250_console_putchar+0x20/0x60 drivers/tty/serial/8250/8250_port.c:2806
 [<ffffffff81caf7c6>] uart_console_write+0x56/0xe0 drivers/tty/serial/serial_core.c:1789
 [<ffffffff81cce12b>] serial8250_console_write+0x2fb/0x870 drivers/tty/serial/8250/8250_port.c:2872
 [<ffffffff81cbd84f>] univ8250_console_write+0x5f/0x70 drivers/tty/serial/8250/8250_core.c:594
 [<ffffffff8121c8ff>] call_console_drivers.constprop.0+0x1ef/0x3f0 kernel/printk/printk.c:1468
 [<ffffffff8121fe02>] console_unlock kernel/printk/printk.c:2335 [inline]
 [<ffffffff8121fe02>] console_unlock+0x602/0xa10 kernel/printk/printk.c:2242
 [<ffffffff812205c2>] vprintk_emit+0x3b2/0x820 kernel/printk/printk.c:1837
 [<ffffffff81220a58>] vprintk+0x28/0x30 kernel/printk/printk.c:1848
 [<ffffffff813afd6f>] printk+0xc2/0xf5 kernel/printk/printk.c:1927
 [<ffffffff82165ce7>] lowmem_scan.cold+0x2e0/0x366 drivers/staging/android/lowmemorykiller.c:180
 [<ffffffff813ee8e2>] do_shrink_slab mm/vmscan.c:357 [inline]
 [<ffffffff813ee8e2>] shrink_slab.part.0+0x402/0xb30 mm/vmscan.c:455
 [<ffffffff813f742c>] shrink_slab mm/vmscan.c:425 [inline]
 [<ffffffff813f742c>] shrink_zone+0x4bc/0x610 mm/vmscan.c:2448
 [<ffffffff813f7bef>] shrink_zones mm/vmscan.c:2603 [inline]
 [<ffffffff813f7bef>] do_try_to_free_pages mm/vmscan.c:2653 [inline]
 [<ffffffff813f7bef>] try_to_free_pages+0x66f/0x1260 mm/vmscan.c:2861
 [<ffffffff813d09af>] __perform_reclaim mm/page_alloc.c:2915 [inline]
 [<ffffffff813d09af>] __alloc_pages_direct_reclaim mm/page_alloc.c:2936 [inline]
 [<ffffffff813d09af>] __alloc_pages_slowpath mm/page_alloc.c:3201 [inline]
 [<ffffffff813d09af>] __alloc_pages_nodemask+0x8af/0x14b0 mm/page_alloc.c:3313
 [<ffffffff8143bedb>] __alloc_pages include/linux/gfp.h:415 [inline]
 [<ffffffff8143bedb>] __alloc_pages_node include/linux/gfp.h:428 [inline]
 [<ffffffff8143bedb>] alloc_pages_node include/linux/gfp.h:442 [inline]
 [<ffffffff8143bedb>] alloc_zeroed_user_highpage_movable include/linux/highmem.h:183 [inline]
 [<ffffffff8143bedb>] do_anonymous_page mm/memory.c:2750 [inline]
 [<ffffffff8143bedb>] handle_pte_fault mm/memory.c:3343 [inline]
 [<ffffffff8143bedb>] __handle_mm_fault mm/memory.c:3474 [inline]
 [<ffffffff8143bedb>] handle_mm_fault+0x220b/0x3140 mm/memory.c:3503
 [<ffffffff810aaa4e>] __do_page_fault+0x28e/0x7f0 arch/x86/mm/fault.c:1243
 [<ffffffff810ab008>] do_page_fault+0x28/0x30 arch/x86/mm/fault.c:1306
 [<ffffffff82719e35>] page_fault+0x25/0x30 arch/x86/entry/entry_64.S:1064
Code: 24 c1 00 00 00 49 8d 7c 24 38 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 d3 e3 80 3c 02 00 75 17 41 03 5c 24 38 89 da ec <5b> 0f b6 c0 41 5c 5d c3 e8 28 29 7c ff eb c2 e8 81 29 7c ff eb 
NMI backtrace for cpu 1
CPU: 1 PID: 20 Comm: khungtaskd Not tainted 4.4.174+ #4
task: ffff8801da6c4740 task.stack: ffff8801d9ef0000
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: 0000:ffff8801d9ef7c88  EFLAGS: 00000046
RAX: 0000000000000000 RBX: 0000000000000c00 RCX: 0000000000000000
RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fc300
RBP: ffff8801d9ef7cb8 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: 00007fe191dac943 CR3: 00000001d9891000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 0000000000000001 ffffffff82e5f2e0 ffffffff831a6ac0 fffffbfff0634c34
 000000000001b6c0 0000000000000008 ffff8801d9ef7cd8 ffffffff81092bee
 0000000000000008 ffffffff82924260 ffff8801d9ef7d30 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