syzbot

   Free memory is -12012kB above reserved
lowmemorykiller: Killing 'syz-executor.1' (6784) (tgid 6784), adj 1000,
   to free 34964kB on behalf of 'udevd' (15682) because
   cache 180kB is below limit 6144kB for oom_score_adj 0
   Free memory is -12012kB above reserved
INFO: task kworker/1:0:24241 blocked for more than 140 seconds.
      Not tainted 4.9.194+ #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/1:0     D27384 24241      2 0x80000000
Workqueue: ipv6_addrconf addrconf_verify_work
 0000000000000083 ffff8801c53ac740 ffff8801d3b44d00 ffff8801db721000
 ffff8801a568c740 ffff8801db721018 ffff8801a1fe7a88 ffffffff8281af8e
 ffff8801a6b247c0 ffff8801a6b247d0 00ff8801db7210a0 ffff8801db7218f0
Call Trace:
 [<00000000d1236a7b>] schedule+0x92/0x1c0 kernel/sched/core.c:3546
 [<00000000b66882bc>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579
 [<000000006360c4d7>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<000000006360c4d7>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621
 [<00000000f70d1d0a>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
 [<0000000061f81d17>] addrconf_verify_work+0xe/0x20 net/ipv6/addrconf.c:4367
 [<00000000888bda27>] process_one_work+0x88b/0x1600 kernel/workqueue.c:2114
 [<00000000888f41b8>] worker_thread+0x5df/0x11d0 kernel/workqueue.c:2251
 [<000000008970da4c>] kthread+0x278/0x310 kernel/kthread.c:211
 [<00000000df4f8674>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:375
INFO: lockdep is turned off.
NMI backtrace for cpu 1
CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.194+ #0
 ffff8801d98d7cc8 ffffffff81b67001 0000000000000001 0000000000000000
 0000000000000001 ffffffff81099d01 dffffc0000000000 ffff8801d98d7d00
 ffffffff81b7229c 0000000000000001 0000000000000000 0000000000000001
Call Trace:
 [<000000009c492a51>] __dump_stack lib/dump_stack.c:15 [inline]
 [<000000009c492a51>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<000000004d94a85e>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99
 [<000000000ac8e381>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60
 [<0000000059a385d5>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<00000000b72212e8>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<00000000b72212e8>] check_hung_task kernel/hung_task.c:126 [inline]
 [<00000000b72212e8>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline]
 [<00000000b72212e8>] watchdog+0x670/0xaf0 kernel/hung_task.c:263
 [<000000008970da4c>] kthread+0x278/0x310 kernel/kthread.c:211
 [<00000000df4f8674>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:375
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 17040 Comm: blkid Not tainted 4.9.194+ #0
task: 00000000b165297c task.stack: 000000003b832e30
RIP: 0010:[<ffffffff8221411c>] 
c [<000000000856b584>] __read_once_size include/linux/compiler.h:264 [inline]
RIP: 0010:[<ffffffff8221411c>] 
c [<000000000856b584>] lowmem_scan+0x42c/0xb70 drivers/staging/android/lowmemorykiller.c:284
RSP: 0018:ffff8801a42076f0  EFLAGS: 00000246
RAX: 1ffff1003a7b2c63 RBX: ffff8801d3d95f00 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff82214103 RDI: ffff8801d3d96318
RBP: ffff8801a4207790 R08: ffff8801d3d966c0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: dffffc0000000000
R13: ffff8801d3d95f00 R14: 00000000000000c6 R15: 0000000000000000
FS:  00007fd7965f5740(0000) GS:ffff8801db600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f35a251f000 CR3: 00000001c47f7000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff82213f2f
c ffffffff8220802f
c ffff880100000001
c 0000000000000000
c
 ffff8801d2092f80
c ffff8801d67bf458
c ffff8801d67bf4b0
c ffff8801a4207860
c
 fffffbfff0601200
c 0000023d00000600
c ffff8801d3d966c0
c ffff8801d64e17c0
c
Call Trace:
 [<00000000774d7a36>] do_shrink_slab mm/vmscan.c:399 [inline]
 [<00000000774d7a36>] shrink_slab.part.0+0x3cf/0xa20 mm/vmscan.c:502
 [<00000000e6ef8023>] shrink_slab mm/vmscan.c:466 [inline]
 [<00000000e6ef8023>] shrink_node+0x1ed/0x750 mm/vmscan.c:2604
 [<0000000006c4a47c>] shrink_zones mm/vmscan.c:2751 [inline]
 [<0000000006c4a47c>] do_try_to_free_pages mm/vmscan.c:2793 [inline]
 [<0000000006c4a47c>] try_to_free_pages+0x397/0xbd0 mm/vmscan.c:3004
 [<000000006c0f503d>] __perform_reclaim mm/page_alloc.c:3332 [inline]
 [<000000006c0f503d>] __alloc_pages_direct_reclaim mm/page_alloc.c:3354 [inline]
 [<000000006c0f503d>] __alloc_pages_slowpath mm/page_alloc.c:3704 [inline]
 [<000000006c0f503d>] __alloc_pages_nodemask+0x930/0x1a80 mm/page_alloc.c:3861
 [<000000006f4266fa>] __alloc_pages include/linux/gfp.h:433 [inline]
 [<000000006f4266fa>] __alloc_pages_node include/linux/gfp.h:446 [inline]
 [<000000006f4266fa>] alloc_pages_node include/linux/gfp.h:460 [inline]
 [<000000006f4266fa>] alloc_zeroed_user_highpage_movable include/linux/highmem.h:183 [inline]
 [<000000006f4266fa>] do_anonymous_page mm/memory.c:2761 [inline]
 [<000000006f4266fa>] handle_pte_fault mm/memory.c:3545 [inline]
 [<000000006f4266fa>] __handle_mm_fault mm/memory.c:3634 [inline]
 [<000000006f4266fa>] handle_mm_fault+0x12e1/0x2420 mm/memory.c:3671
 [<00000000fe958255>] __do_page_fault+0x3f0/0xa60 arch/x86/mm/fault.c:1401
 [<00000000659b128f>] do_page_fault+0x28/0x30 arch/x86/mm/fault.c:1464
 [<00000000ec681b3a>] page_fault+0x25/0x30 arch/x86/entry/entry_64.S:956
Code: 
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c