syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P8678/1:b..l P1149/2:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=42633, q=888 ncpus=2)
task:kworker/u8:11   state:R  running task     stack:20992 pid:1149  tgid:1149  ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: ipv6_addrconf addrconf_dad_work
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x1585/0x5340 kernel/sched/core.c:6907
 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:7091
 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12
 __local_bh_enable_ip+0xe1/0x130 kernel/softirq.c:457
 neigh_hh_init net/core/neighbour.c:1594 [inline]
 neigh_resolve_output+0x2b7/0x750 net/core/neighbour.c:1609
 NF_HOOK_COND include/linux/netfilter.h:307 [inline]
 ip6_output+0x340/0x550 net/ipv6/ip6_output.c:246
 NF_HOOK include/linux/netfilter.h:318 [inline]
 ndisc_send_skb+0xbaa/0x14e0 net/ipv6/ndisc.c:512
 addrconf_dad_completed+0x909/0xe60 net/ipv6/addrconf.c:4365
 addrconf_dad_work+0xc5e/0x14c0 net/ipv6/addrconf.c:-1
 process_one_work kernel/workqueue.c:3275 [inline]
 process_scheduled_works+0xb02/0x1830 kernel/workqueue.c:3358
 worker_thread+0xa50/0xfc0 kernel/workqueue.c:3439
 kthread+0x388/0x470 kernel/kthread.c:467
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
task:syz.4.752       state:R  running task     stack:27016 pid:8678  tgid:8678  ppid:5839   task_flags:0x40044c flags:0x00080003
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x1585/0x5340 kernel/sched/core.c:6907
 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7234
 irqentry_exit+0x599/0x620 kernel/entry/common.c:239
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:__orc_find arch/x86/kernel/unwind_orc.c:110 [inline]
RIP: 0010:orc_find arch/x86/kernel/unwind_orc.c:238 [inline]
RIP: 0010:unwind_next_frame+0x2b4/0x23c0 arch/x86/kernel/unwind_orc.c:510
Code: 00 00 fc ff df 0f 84 1c 04 00 00 4a 8d 14 ad 84 98 23 90 45 29 e8 4a 8d 1c 82 48 83 c3 fc 49 89 d5 48 39 da 0f 86 21 02 00 00 <49> 29 d5 49 c1 fd 02 4a 8d 04 6d 00 00 00 00 4c 01 e8 48 8d 14 46
RSP: 0018:ffffc9000c58f558 EFLAGS: 00000202
RAX: ffffffff903356d0 RBX: ffffffff903356d4 RCX: ffffffff903356d8
RDX: ffffffff903356d4 RSI: ffffffff90b431a8 RDI: ffffffff8c2797a0
RBP: ffffffff903356d8 R08: 0000000000000001 R09: ffffffff8e7603e0
R10: ffffc9000c58f678 R11: ffffffff81b0a7f0 R12: ffffffff8239de61
R13: ffffffff903356d4 R14: ffffc9000c58f628 R15: ffffffff903356d4
 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
 save_stack+0x122/0x230 mm/page_owner.c:165
 __reset_page_owner+0x71/0x1f0 mm/page_owner.c:320
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1432 [inline]
 __free_frozen_pages+0xc00/0xd90 mm/page_alloc.c:2977
 vfree+0x25a/0x400 mm/vmalloc.c:3479
 kcov_put kernel/kcov.c:442 [inline]
 kcov_close+0x28/0x50 kernel/kcov.c:543
 __fput+0x44f/0xa70 fs/file_table.c:469
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x69b/0x2310 kernel/exit.c:971
 do_group_exit+0x21b/0x2d0 kernel/exit.c:1112
 get_signal+0x1284/0x1330 kernel/signal.c:3034
 arch_do_signal_or_restart+0xbc/0x830 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
 exit_to_user_mode_loop+0x86/0x480 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
 do_syscall_64+0x32d/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f67cb75c84e
RSP: 002b:00007f67cc6d8f58 EFLAGS: 00000246 ORIG_RAX: 00000000000000e6
RAX: fffffffffffffdfc RBX: 00007f67cc6d96c0 RCX: 00007f67cb75c84e
RDX: 00007f67cc6d8fb0 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f67cb8327e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f67cba16038 R14: 00007f67cba15fa0 R15: 00007f67cbb3fa48
 </TASK>