rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	(detected by 1, t=10505 jiffies, g=198441, q=78 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10505 (4295000775-4294990270), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread timer wakeup didn't happen for 10504 jiffies! g198441 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x200
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=43163
rcu: rcu_preempt kthread starved for 10505 jiffies! g198441 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:28368 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 __schedule+0x17d9/0x56c0
 schedule+0x164/0x2b0
 schedule_timeout+0x152/0x2c0
 rcu_gp_fqs_loop+0x30c/0x11f0
 rcu_gp_kthread+0x9e/0x2b0
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 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: 19437 Comm: syz-executor Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:lock_release+0x266/0x3c0
Code: 89 f6 48 8b 54 24 18 e8 28 2f 00 00 48 8b 5c 24 08 48 c7 c7 d0 c5 4a 8e e8 27 cc 2c 0a b8 ff ff ff ff 65 0f c1 05 ea dd c9 11 <83> f8 01 75 2e 9c 58 a9 00 02 00 00 75 42 f7 c3 00 02 00 00 75 47
RSP: 0018:ffffc90000007d58 EFLAGS: 00000057
RAX: 0000000000000001 RBX: 0000000000000087 RCX: 0000000080010003
RDX: 0000000000000008 RSI: ffffffff8e4ac5d0 RDI: ffffffff8c4bb580
RBP: ffff8880285ee620 R08: ffff8881bf5e2327 R09: 0000000000000000
R10: ffff8881bf5e2318 R11: ffffed1037ebc465 R12: 0000000000000008
R13: 0000000000000008 R14: ffff8881210281d8 R15: ffff8880285ed940
FS:  0000555567a87500(0000) GS:ffff88818d959000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1097c27dac CR3: 000000010fb06000 CR4: 00000000000006f0
Call Trace:
 <IRQ>
 _raw_spin_unlock_irqrestore+0x1b/0x80
 __hrtimer_run_queues+0x2bf/0xa10
 hrtimer_interrupt+0x448/0x910
 __sysvec_apic_timer_interrupt+0x102/0x430
 sysvec_apic_timer_interrupt+0xa1/0xc0
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:its_return_thunk+0x0/0x10
Code: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc <c3> cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 e9 1b 79 60 f5 cc
RSP: 0018:ffffc90003c5f278 EFLAGS: 00000202
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000080000003
RDX: 0000000000000000 RSI: ffffffff8c4bb560 RDI: ffffffff8c4bb520
RBP: 0000000000000000 R08: ffffffff82403b67 R09: 0000000000000000
R10: 0000000000000000 R11: ffffffff8eb59c60 R12: 0000000000031be0
R13: dffffc0000000000 R14: ffff88814fe590d0 R15: 0000000000001000
 rcu_read_lock_held+0x15/0x50
 page_ext_lookup+0xe7/0x180
 page_table_check_set+0x228/0x530
 copy_pmd_range+0x477a/0x5880
 copy_page_range+0xc26/0x1250
 dup_mmap+0xf21/0x1d90
 copy_mm+0x11a/0x480
 copy_process+0x1e3e/0x4390
 kernel_clone+0x2d7/0x940
 __x64_sys_clone+0x1b6/0x230
 do_syscall_64+0x174/0x580
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1a3edc6bd2
Code: 89 e7 e8 71 8b f7 ff 45 31 c0 31 d2 31 f6 64 48 8b 04 25 10 00 00 00 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 66 89 c5 85 c0 75 3b 64 48 8b 04 25 10 00 00
RSP: 002b:00007ffd9cde6d40 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007ffd9cde6d40 RCX: 00007f1a3edc6bd2
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 00007ffd9cde6ecc R08: 0000000000000000 R09: 0000000000000001
R10: 0000555567a877d0 R11: 0000000000000246 R12: 0000000000000001
R13: 00000000000927c0 R14: 0000000000081bd0 R15: 00007ffd9cde6f20
 </TASK>
