rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	(detected by 0, t=10502 jiffies, g=18781, q=413 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294958330-4294947828), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g18781 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x200
rcu: 	Possible timer handling issue on cpu=1 timer-softirq=4549
rcu: rcu_preempt kthread starved for 10502 jiffies! g18781 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x200 ->cpu=1
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:28096 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 __schedule+0x153e/0x4fe0
 schedule+0x164/0x360
 schedule_timeout+0x158/0x2c0
 rcu_gp_fqs_loop+0x312/0x11d0
 rcu_gp_kthread+0x9e/0x2b0
 kthread+0x388/0x470
 ret_from_fork+0x51b/0xa40
 ret_from_fork_asm+0x1a/0x30
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 24 Comm: kworker/1:0 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
Workqueue:  0x0 (rcu_gp)
RIP: 0010:_find_first_zero_bit+0x64/0xb0
Code: 06 48 83 f8 ff 74 2b 45 31 ed 48 f7 d0 f3 48 0f bc c0 4c 01 e8 48 39 d8 48 0f 43 c3 eb 05 31 db 48 89 d8 5b 41 5c 41 5d 41 5e <41> 5f e9 15 1d e8 06 cc 49 83 c6 08 45 31 ed 4d 89 f7 eb 11 49 8b
RSP: 0018:ffffc900001e7a98 EFLAGS: 00000046
RAX: 0000000000000002 RBX: ffff88816fe0c8d0 RCX: dffffc0000000000
RDX: 0000000000000002 RSI: 0000000000000002 RDI: ffff88816fe0c8d0
RBP: 0000000080000000 R08: ffff88816fe0c753 R09: 1ffff1102dfc18ea
R10: dffffc0000000000 R11: ffffed102dfc18eb R12: dffffc0000000000
R13: 1ffffffff1bf33d3 R14: 0000000080000000 R15: 0000000000000002
FS:  0000000000000000(0000) GS:ffff8882a96e7000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5935052ff8 CR3: 000000016fafe000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 mm_get_cid+0xc7/0x130
 __schedule+0x21ff/0x4fe0
 schedule+0x164/0x360
 worker_thread+0xbdd/0xee0
 kthread+0x388/0x470
 ret_from_fork+0x51b/0xa40
 ret_from_fork_asm+0x1a/0x30
 </TASK>
