rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (0 ticks this GP) idle=65cc/1/0x4000000000000000 softirq=49924/49924 fqs=0
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P12891/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=42121, q=135 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 12886 Comm: syz.1.1991 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:check_preemption_disabled+0x40/0x120
Code: 08 65 8b 05 c6 5e 26 07 65 8b 0d bb 5e 26 07 f7 c1 ff ff ff 7f 74 23 65 48 8b 0d 9b 5e 26 07 48 3b 4c 24 08 0f 85 cc 00 00 00 <48> 83 c4 10 5b 41 5e 41 5f 5d e9 81 ca 02 00 cc 48 c7 04 24 00 00
RSP: 0018:ffffc900001dfda0 EFLAGS: 00000046
RAX: 0000000000000001 RBX: 0000000000000087 RCX: 5cdba79bcb0b4a00
RDX: 0000000000000003 RSI: ffffffff8dba9832 RDI: ffffffff8be33e00
RBP: ffff8880204c2828 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff5200003bfb8 R12: 0000000000000003
R13: 0000000000000003 R14: ffff888136627a98 R15: ffff8880204c1cc0
FS:  00007f30f41a76c0(0000) GS:ffff8881a3c13000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32005ff8 CR3: 0000000037fca000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 lock_release+0x27a/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:lock_acquire+0x175/0x360
Code: 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 7b 5f 03 11 <48> 3b 44 24 58 0f 85 f2 00 00 00 48 83 c4 60 5b 41 5c 41 5d 41 5e
RSP: 0018:ffffc900001e0678 EFLAGS: 00000206
RAX: 5cdba79bcb0b4a00 RBX: 0000000000000000 RCX: 5cdba79bcb0b4a00
RDX: 0000000000000000 RSI: ffffffff8dba9832 RDI: ffffffff8be33e00
RBP: ffffffff8172d195 R08: 0000000000000000 R09: ffffffff8172d195
R10: ffffc900001e0838 R11: ffffffff81ac4d00 R12: 0000000000000002
R13: ffffffff8e13a120 R14: 0000000000000000 R15: 0000000000000246
 unwind_next_frame+0xc2/0x2390
 arch_stack_walk+0x11c/0x150
 stack_trace_save+0x9c/0xe0
 kasan_save_track+0x3e/0x80
 kasan_save_free_info+0x46/0x50
 __kasan_slab_free+0x5b/0x80
 kmem_cache_free+0x18f/0x400
 rcu_core+0xcab/0x1770
 handle_softirqs+0x286/0x870
 __irq_exit_rcu+0xca/0x1f0
 irq_exit_rcu+0x9/0x30
 sysvec_apic_timer_interrupt+0xa6/0xc0
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:lock_acquire+0x175/0x360
Code: 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 7b 5f 03 11 <48> 3b 44 24 58 0f 85 f2 00 00 00 48 83 c4 60 5b 41 5c 41 5d 41 5e
RSP: 0018:ffffc90002ecfaf8 EFLAGS: 00000206
RAX: 5cdba79bcb0b4a00 RBX: 0000000000000000 RCX: 5cdba79bcb0b4a00
RDX: 0000000000000001 RSI: ffffffff8dba9832 RDI: ffffffff8be33e00
RBP: ffffffff81b2f090 R08: 0000000000000000 R09: ffffffff81b2f090
R10: ffffc90002ecfc40 R11: fffff520005d9f8b R12: 0000000000000002
R13: ffffffff8e13a120 R14: 0000000000000000 R15: 0000000000000246
 futex_hash+0x5d/0x2d0
 futex_wake+0x161/0x560
 do_futex+0x395/0x420
 __se_sys_futex+0x36f/0x400
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f30f338eba9
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:00007f30f41a70e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: ffffffffffffffda RBX: 00007f30f35d5fa8 RCX: 00007f30f338eba9
RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007f30f35d5fac
RBP: 00007f30f35d5fa0 R08: 7fffffffffffffff R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f30f35d6038 R14: 00007ffc9eb305e0 R15: 00007ffc9eb306c8
 </TASK>
task:syz.2.1993      state:R  running task     stack:26264 pid:12891 tgid:12890 ppid:5848   task_flags:0x400140 flags:0x00004000
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 preempt_schedule_irq+0xb5/0x150
 irqentry_exit+0x6f/0x90
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:unwind_next_frame+0xb1b/0x2390
Code: 10 49 89 dd 49 c1 ed 03 48 b8 00 00 00 00 00 fc ff df 41 80 7c 05 00 00 74 08 48 89 df e8 ed 62 b0 00 48 89 9c 24 88 00 00 00 <49> 8d 5c 24 f8 4d 8b 66 10 48 b8 00 00 00 00 00 fc ff df 48 8b 4c
RSP: 0018:ffffc900000c7138 EFLAGS: 00000246
RAX: dffffc0000000000 RBX: ffffc900000c7218 RCX: ffffffff8fb7dd70
RDX: ffffffff90340dfc RSI: 0000000000000002 RDI: ffffffff8be33da0
RBP: 1ffff92000018e42 R08: 0000000000000001 R09: ffffffff8172d195
R10: ffffc900000c7258 R11: ffffffff81ac4d00 R12: ffffc900000c7d60
R13: 1ffff92000018e43 R14: ffffc900000c7208 R15: ffffc900000c0000
 arch_stack_walk+0x11c/0x150
 stack_trace_save+0x9c/0xe0
 kasan_save_track+0x3e/0x80
 __kasan_slab_alloc+0x6c/0x80
 kmem_cache_alloc_noprof+0x1c1/0x3c0
 __proc_create+0x382/0x8d0
 proc_create_data+0xa5/0x190
 cache_register_net+0x45b/0x4c0
 nfsd_idmap_init+0x96/0x1f0
 nfsd_net_init+0x4d/0x480
 ops_init+0x35c/0x5c0
 setup_net+0x10c/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: 0033:0x7fbef338eba9
RSP: 002b:00007fbef42abfe8 EFLAGS: 00000206 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007fbef35d5fa0 RCX: 00007fbef338eba9
RDX: 0000200000000140 RSI: 0000200000000010 RDI: 0000000041001000
RBP: 00007fbef3411e19 R08: 00002000000001c0 R09: 00002000000001c0
R10: 0000200000000180 R11: 0000000000000206 R12: 0000000000000000
R13: 00007fbef35d6038 R14: 00007fbef35d5fa0 R15: 00007ffc4ee98a18
 </TASK>
rcu: rcu_preempt kthread starved for 10502 jiffies! g42121 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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  running task     stack:26728 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: 0 UID: 0 PID: 12885 Comm: syz.1.1991 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 23 7a 0b 00 41 83 e6 01 75 11 e8 d8 75 0b 00 4d 89 fe eb 3f e8 ce 75 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 b1 75 0b 00
RSP: 0018:ffffc90002f3fa40 EFLAGS: 00000293
RAX: ffffffff81b44b4f RBX: ffffc90002f3fa88 RCX: ffff888109475640
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90002f3fb30 R08: ffffffff8fa3a837 R09: 1ffffffff1f47506
R10: dffffc0000000000 R11: ffffffff81706100 R12: 1ffff920005e7f51
R13: dffffc0000000000 R14: 1ffff920005e7f4c R15: 1ffff920005e7f4c
FS:  0000555563a29500(0000) GS:ffff8880b8613000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32616ff8 CR3: 0000000037fca000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 event_function_call+0x326/0x970
 perf_event_release_kernel+0x15d/0x510
 perf_release+0x38/0x50
 __fput+0x44c/0xa70
 task_work_run+0x1d4/0x260
 exit_to_user_mode_loop+0xec/0x110
 do_syscall_64+0x2bd/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f30f338eba9
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:00007ffc9eb30828 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007f30f35d7da0 RCX: 00007f30f338eba9
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f30f35d7da0 R08: 000000000000d334 R09: 0000001c9eb30b1f
R10: 00000000003f2aa8 R11: 0000000000000246 R12: 000000000005a00b
R13: 00007f30f35d6090 R14: ffffffffffffffff R15: 00007ffc9eb30940
 </TASK>
