rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	(detected by 1, t=10502 jiffies, g=10461, q=648 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294955864-4294945362), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g10461 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x200
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=3380
rcu: rcu_preempt kthread starved for 10502 jiffies! g10461 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x200 ->cpu=0
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:R stack:27656 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_timeout+0x12b/0x270
 rcu_gp_fqs_loop+0x301/0x1540
 rcu_gp_kthread+0x99/0x390
 kthread+0x711/0x8a0
 ret_from_fork+0x439/0x7d0
 ret_from_fork_asm+0x1a/0x30
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 6651 Comm: syz.0.179 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:rcu_is_watching+0x44/0xb0
Code: 73 65 49 bf 00 00 00 00 00 fc ff df 4c 8d 34 dd 10 1d be 8d 4c 89 f0 48 c1 e8 03 42 80 3c 38 00 74 08 4c 89 f7 e8 6c c1 7c 00 <48> c7 c3 98 df a1 92 49 03 1e 48 89 d8 48 c1 e8 03 42 0f b6 04 38
RSP: 0018:ffffc90000007378 EFLAGS: 00000046
RAX: 1ffffffff1b7c3a2 RBX: 0000000000000000 RCX: 623a10bbb11d0100
RDX: 0000000000010100 RSI: ffffffff8be33be0 RDI: ffffffff8be33ba0
RBP: ffffc90000007498 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000000e70 R12: dffffc0000000000
R13: ffffffff81ada71e R14: ffffffff8dbe1d10 R15: dffffc0000000000
FS:  00007f3aaa0c16c0(0000) GS:ffff8880b8615000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000000023c0 CR3: 0000000109116000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 lock_release+0x4b/0x3e0
 _raw_spin_unlock_irqrestore+0x70/0x110
 hrtimer_try_to_cancel+0x3be/0x420
 hrtimer_cancel+0x3b/0x50
 cpu_clock_event_stop+0xd9/0x130
 __perf_event_overflow+0x580/0xe40
 perf_swevent_hrtimer+0x3c5/0x550
 __hrtimer_run_queues+0x4e0/0xc60
 hrtimer_interrupt+0x45b/0xaa0
 __sysvec_apic_timer_interrupt+0x10b/0x410
 sysvec_apic_timer_interrupt+0x52/0xc0
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:__kasan_slab_pre_free+0x0/0x30
Code: 89 f3 e8 63 2c 00 00 48 89 d8 5b c3 cc cc cc cc cc 66 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <66> 0f 1f 00 48 8b 05 75 b3 80 0d 48 89 f1 48 29 c1 48 81 f9 00 00
RSP: 0018:ffffc90000007c38 EFLAGS: 00000202
RAX: ffff888136400001 RBX: ffff88801ef70e00 RCX: fffffffee8b70e01
RDX: ffffffff81a80b0b RSI: ffff88801ef70e00 RDI: ffff88801b698a00
RBP: ffffc90000007ed0 R08: ffffffff8fa3a637 R09: 1ffffffff1f474c6
R10: dffffc0000000000 R11: fffffbfff1f474c7 R12: 0000000000000000
R13: ffffffff81a80a97 R14: ffffea00007bdc00 R15: ffff88801b698a00
 slab_free_after_rcu_debug+0x10b/0x2a0
 rcu_core+0xcab/0x1770
 handle_softirqs+0x286/0x870
 do_softirq+0xec/0x180
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0x17d/0x1c0
 __dev_queue_xmit+0x1d79/0x3b50
 __netlink_deliver_tap+0x5ad/0x850
 netlink_deliver_tap+0x19c/0x1b0
 netlink_sendskb+0x68/0x140
 netlink_unicast+0x397/0x9e0
 netlink_rcv_skb+0x28c/0x470
 netlink_unicast+0x82f/0x9e0
 netlink_sendmsg+0x805/0xb30
 __sock_sendmsg+0x21c/0x270
 ____sys_sendmsg+0x505/0x830
 ___sys_sendmsg+0x21f/0x2a0
 __x64_sys_sendmsg+0x19b/0x260
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3aa918ec29
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f3aaa0c1038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f3aa93d5fa0 RCX: 00007f3aa918ec29
RDX: 0000000000000000 RSI: 0000200000000000 RDI: 000000000000000a
RBP: 00007f3aa9211e41 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3aa93d6038 R14: 00007f3aa93d5fa0 R15: 00007ffc2faeda38
 </TASK>
