syzbot

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-....: (10501 ticks this GP) idle=cb6/1/0x4000000000000002 softirq=11031/11031 fqs=5250 
	(t=10502 jiffies g=6629 q=483)
NMI backtrace for cpu 0
CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted 5.5.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events linkwatch_event
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1fb/0x318 lib/dump_stack.c:118
 nmi_cpu_backtrace+0xaf/0x1a0 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x174/0x290 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x10/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x15a/0x220 kernel/rcu/tree_stall.h:254
 print_cpu_stall kernel/rcu/tree_stall.h:455 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:529 [inline]
 rcu_pending kernel/rcu/tree.c:2827 [inline]
 rcu_sched_clock_irq+0xe25/0x1ad0 kernel/rcu/tree.c:2271
 update_process_times+0x12d/0x180 kernel/time/timer.c:1726
 tick_sched_handle kernel/time/tick-sched.c:167 [inline]
 tick_sched_timer+0x263/0x420 kernel/time/tick-sched.c:1310
 __run_hrtimer kernel/time/hrtimer.c:1517 [inline]
 __hrtimer_run_queues+0x403/0x840 kernel/time/hrtimer.c:1579
 hrtimer_interrupt+0x38c/0xda0 kernel/time/hrtimer.c:1641
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline]
 smp_apic_timer_interrupt+0x109/0x280 arch/x86/kernel/apic/apic.c:1135
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 </IRQ>
RIP: 0010:free_thread_stack+0x133/0x590 kernel/fork.c:280
Code: 00 ea ff ff 48 01 c7 be 03 00 00 00 e8 86 91 61 00 e9 5d 04 00 00 e8 3c 2c 2e 00 48 89 df 31 f6 e8 02 8d 6f 00 43 80 3c 2e 00 <74> 08 4c 89 e7 e8 73 94 6a 00 49 8b 1c 24 48 83 c3 08 48 89 d8 48
RSP: 0018:ffffc90000cbf2a8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000001 RBX: ffffea000263e4c0 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffea000263e4c0
RBP: ffffc90000cbf2e0 R08: dffffc0000000000 R09: fffffbfff124248a
R10: fffffbfff124248a R11: 0000000000000000 R12: ffff88808fee8ca0
R13: dffffc0000000000 R14: 1ffff11011fdd194 R15: ffff888097a079f8
 release_task_stack kernel/fork.c:440 [inline]
 put_task_stack+0xa3/0x130 kernel/fork.c:451
 finish_task_switch+0x3f1/0x550 kernel/sched/core.c:3256
 context_switch kernel/sched/core.c:3388 [inline]
 __schedule+0x9a8/0xcc0 kernel/sched/core.c:4081
 preempt_schedule_irq+0xc1/0x140 kernel/sched/core.c:4338
 retint_kernel+0x1b/0x2b
RIP: 0010:check_kcov_mode kernel/kcov.c:153 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x14/0x50 kernel/kcov.c:187
Code: 00 00 00 48 8b 3d f4 f4 ed 07 48 89 de e8 84 f4 3b 00 5b 5d c3 cc 48 8b 04 24 65 48 8b 0c 25 c0 1d 02 00 65 8b 15 38 5f 8b 7e <f7> c2 00 01 1f 00 75 2c 8b 91 80 13 00 00 83 fa 02 75 21 48 8b 91
RSP: 0000:ffffc90000cbf4f8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: ffffffff8165c266 RBX: 1ffff92000197ec1 RCX: ffff8880a999c140
RDX: 0000000080000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90000cbf550 R08: ffffffff8165c225 R09: ffffc90000cbf560
R10: fffff52000197eb8 R11: 0000000000000000 R12: ffffc90000cbf600
R13: 1ffff92000197ec2 R14: 000000000000000e R15: 0000000000000000
 arch_stack_walk+0xa8/0xe0 arch/x86/kernel/stacktrace.c:27
 stack_trace_save+0xb6/0x150 kernel/stacktrace.c:123
 save_stack mm/kasan/common.c:72 [inline]
 set_track mm/kasan/common.c:80 [inline]
 __kasan_kmalloc+0x11c/0x1b0 mm/kasan/common.c:513
 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:521
 slab_post_alloc_hook mm/slab.h:584 [inline]
 slab_alloc_node mm/slab.c:3263 [inline]
 kmem_cache_alloc_node_trace+0x225/0x2d0 mm/slab.c:3593
 __do_kmalloc_node mm/slab.c:3615 [inline]
 __kmalloc_node_track_caller+0x3c/0x60 mm/slab.c:3630
 __kmalloc_reserve net/core/skbuff.c:141 [inline]
 __alloc_skb+0xe8/0x500 net/core/skbuff.c:209
 alloc_skb include/linux/skbuff.h:1049 [inline]
 nlmsg_new include/net/netlink.h:888 [inline]
 inet6_ifinfo_notify+0x70/0x110 net/ipv6/addrconf.c:5864
 addrconf_notify+0x3457/0x3c90 net/ipv6/addrconf.c:3617
 notifier_call_chain kernel/notifier.c:83 [inline]
 __raw_notifier_call_chain kernel/notifier.c:361 [inline]
 raw_notifier_call_chain+0xec/0x190 kernel/notifier.c:368
 call_netdevice_notifiers_info net/core/dev.c:1893 [inline]
 netdev_state_change+0x147/0x1f0 net/core/dev.c:1378
 linkwatch_do_dev+0x10e/0x160 net/core/link_watch.c:159
 __linkwatch_run_queue+0x446/0x730 net/core/link_watch.c:204
 linkwatch_event+0x4c/0x60 net/core/link_watch.c:243
 process_one_work+0x7ef/0x10d0 kernel/workqueue.c:2264
 worker_thread+0xc01/0x1630 kernel/workqueue.c:2410
 kthread+0x332/0x350 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352