rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (1 GPs behind) idle=bb84/1/0x4000000000000000 softirq=23714/23716 fqs=0
rcu: 	(detected by 1, t=10505 jiffies, g=16397, q=196 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 7432 Comm: syz.0.406 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:lock_acquire+0x15c/0x360
Code: ff ff ff 65 0f c1 05 83 db 03 11 83 f8 01 0f 85 c9 00 00 00 48 c7 44 24 30 00 00 00 00 9c 8f 44 24 30 f7 44 24 30 00 02 00 00 <0f> 85 cd 00 00 00 f7 44 24 08 00 02 00 00 74 01 fb 65 48 8b 05 3b
RSP: 0018:ffffc900000077e0 EFLAGS: 00000046
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 4776583dcf47e900
RDX: 0000000000000000 RSI: ffffffff8dbaacc4 RDI: ffffffff8be34480
RBP: ffffffff81adabcb R08: 0000000000000000 R09: ffffffff81adabcb
R10: dffffc0000000000 R11: ffffed1009604f51 R12: 0000000000000000
R13: ffff88804b027a98 R14: 0000000000000001 R15: 0000000000000046
FS:  00007fe17e8946c0(0000) GS:ffff8880b860f000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe17e851fc8 CR3: 000000001ab8c000 CR4: 00000000000006f0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000082
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 _raw_spin_lock_irqsave+0xa7/0xf0
 hrtimer_try_to_cancel+0x22b/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+0xa1/0xc0
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:acct_collect+0x1aa/0x770
Code: 48 c7 c6 ff ff ff ff e8 54 13 be 09 48 85 c0 0f 84 cd 00 00 00 49 89 c5 31 db 49 8d 7d 08 48 89 f8 48 c1 e8 03 42 80 3c 30 00 <74> 05 e8 7f d1 6e 00 4d 8b 7d 08 4c 89 e8 48 c1 e8 03 42 80 3c 30
RSP: 0018:ffffc900087c7960 EFLAGS: 00000246
RAX: 1ffff11005241091 RBX: 0000000004c7c000 RCX: ffff888104f91cc0
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff888029208488
RBP: ffffc900087c7ad0 R08: ffff888104f91cc0 R09: 0000000000000004
R10: 0000000000000003 R11: 0000000000000000 R12: ffffc900087c7a00
R13: ffff888029208480 R14: dffffc0000000000 R15: 00007fe17d3fd000
 do_exit+0x5c3/0x2300
 do_group_exit+0x21c/0x2d0
 get_signal+0x1286/0x1340
 arch_do_signal_or_restart+0x9a/0x750
 exit_to_user_mode_loop+0x75/0x110
 do_syscall_64+0x2bd/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe17d98ec29
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:00007fe17e894038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: 0000000000000000 RBX: 00007fe17dbd5fa0 RCX: 00007fe17d98ec29
RDX: 0000000000000005 RSI: 0000000000002402 RDI: 0000000000000025
RBP: 00007fe17da11e41 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe17dbd6038 R14: 00007fe17dbd5fa0 R15: 00007ffd51548fe8
 </TASK>
rcu: rcu_preempt kthread starved for 10505 jiffies! g16397 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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  running task     stack:27224 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:
CPU: 1 UID: 0 PID: 7409 Comm: syz.2.401 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:smp_call_function_single+0x3a9/0x590
Code: 33 44 89 f6 83 e6 01 31 ff e8 83 7a 0b 00 41 83 e6 01 75 11 e8 38 76 0b 00 4d 89 fe eb 3f e8 2e 76 0b 00 eb 3c 4d 89 fe f3 90 <43> 0f b6 04 2c 84 c0 75 0f f7 03 01 00 00 00 74 1d e8 11 76 0b 00
RSP: 0018:ffffc900082476c0 EFLAGS: 00000293
RAX: ffffffff81b44f8f RBX: ffffc90008247708 RCX: ffff88810dba1cc0
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc900082477b0 R08: ffffffff8fa3c237 R09: 1ffffffff1f47846
R10: dffffc0000000000 R11: ffffffff81706100 R12: 1ffff92001048ee1
R13: dffffc0000000000 R14: 1ffff92001048edc R15: 1ffff92001048edc
FS:  00007f88593666c0(0000) GS:ffff8881a3c0f000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000028b44000 CR4: 00000000000006f0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 rcu_barrier+0x360/0x570
 setup_net+0x2d8/0x320
 copy_net_ns+0x31b/0x4d0
 create_new_namespaces+0x3f3/0x720
 copy_namespaces+0x438/0x4b0
 copy_process+0x1733/0x3c00
 kernel_clone+0x21e/0x840
 __x64_sys_clone+0x18b/0x1e0
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f885858ec29
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:00007f8859365fe8 EFLAGS: 00000202 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007f88587d5fa0 RCX: 00007f885858ec29
RDX: 0000200000000140 RSI: 0000200000000100 RDI: 0000000068001680
RBP: 00007f8858611e41 R08: 0000200000000240 R09: 0000200000000240
R10: 0000200000000200 R11: 0000000000000202 R12: 0000000000000000
R13: 00007f88587d6038 R14: 00007f88587d5fa0 R15: 00007ffff71d2f78
 </TASK>
