rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (0 ticks this GP) idle=229c/1/0x4000000000000000 softirq=23435/23435 fqs=15
rcu: 	(detected by 1, t=10506 jiffies, g=16957, q=196 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 7737 Comm: syz.3.488 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+0xac8/0xd20
Code: 8b 3c 24 48 83 78 40 00 0f 84 6a 01 00 00 4c 89 f6 89 ea 4c 89 f9 e8 17 38 00 00 85 c0 0f 84 e4 01 00 00 41 f6 46 22 10 75 2e <48> 8b 1c 24 4c 89 bb e0 0a 00 00 8b 83 e8 0a 00 00 ff c0 89 83 e8
RSP: 0018:ffffc90000007750 EFLAGS: 00000046
RAX: 0000000000000001 RBX: 0000000000000004 RCX: 2b0f309030d2ef00
RDX: 0000000000000000 RSI: ffff888021f4c510 RDI: ffff888021f4b980
RBP: 0000000000000001 R08: 0000000000000000 R09: ffffffff81ada58b
R10: dffffc0000000000 R11: ffffed1009604f51 R12: 0000000000000068
R13: ffff888021f4c470 R14: ffff888021f4c510 R15: d6bf87c490213bdc
FS:  00007fddf85f66c0(0000) GS:ffff8880b8613000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000000d000 CR3: 0000000023030000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 lock_acquire+0x120/0x360
 _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:finish_task_switch+0x26b/0x950
Code: 0f 84 3c 01 00 00 48 85 db 0f 85 63 01 00 00 0f 1f 44 00 00 4c 8b 75 d0 4c 89 e7 e8 df 76 ec 09 e8 8a 41 36 00 fb 4c 8b 65 c0 <49> 8d bc 24 18 16 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 28 84 c0
RSP: 0018:ffffc9000483ee38 EFLAGS: 00000282
RAX: 2b0f309030d2ef00 RBX: 0000000000000000 RCX: 2b0f309030d2ef00
RDX: 0000000000000007 RSI: ffffffff8d9b9fdf RDI: ffffffff8be33c00
RBP: ffffc9000483ee90 R08: ffffffff8fa38f37 R09: 1ffffffff1f471e6
R10: dffffc0000000000 R11: fffffbfff1f471e7 R12: ffff888021f4b980
R13: dffffc0000000000 R14: ffff88810966b980 R15: ffff88804b03ab58
 __schedule+0x17a0/0x4cc0
 preempt_schedule_common+0x83/0xd0
 preempt_schedule+0xae/0xc0
 preempt_schedule_thunk+0x16/0x30
 _raw_spin_unlock+0x3f/0x50
 __handle_mm_fault+0x3a6c/0x5440
 handle_mm_fault+0x40a/0x8e0
 do_user_addr_fault+0x764/0x1390
 exc_page_fault+0x76/0xf0
 asm_exc_page_fault+0x26/0x30
RIP: 0010:rep_movs_alternative+0x75/0x90
Code: 05 c3 cc cc cc cc 48 8b 06 48 89 07 48 8d 47 08 48 83 e0 f8 48 29 f8 48 01 c7 48 01 c6 48 29 c1 48 89 c8 48 c1 e9 03 83 e0 07 <f3> 48 a5 89 c1 85 c9 75 91 c3 cc cc cc cc 48 8d 0c c8 eb 86 cc cc
RSP: 0018:ffffc9000483f5f8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8881061e8000 RCX: 0000000000000d10
RDX: 0000000000000001 RSI: 00002000000d2000 RDI: ffff8881061e9780
RBP: ffffc9000483f770 R08: ffff8881061effff R09: 1ffff11020c3dfff
R10: dffffc0000000000 R11: ffffed1020c3e000 R12: 1ffff92000907fbf
R13: 00002000000d0880 R14: ffffc9000483fe08 R15: 0000000000008000
 _copy_from_iter+0x24f/0x1790
 kcm_sendmsg+0xf00/0x2ad0
 __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: 0033:0x7fddfa38eba9
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:00007fddf85f6038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fddfa5d5fa0 RCX: 00007fddfa38eba9
RDX: 0000000000000000 RSI: 0000200000002080 RDI: 0000000000000004
RBP: 00007fddfa411e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fddfa5d6038 R14: 00007fddfa5d5fa0 R15: 00007ffc7e061f98
 </TASK>
rcu: rcu_preempt kthread starved for 10430 jiffies! g16957 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:26664 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: 7736 Comm: syz.3.488 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:ffffc9000485fa40 EFLAGS: 00000293
RAX: ffffffff81b4494f RBX: ffffc9000485fa88 RCX: ffff888021f49cc0
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc9000485fb30 R08: ffffc9000485f8e7 R09: 1ffff9200090bf1c
R10: dffffc0000000000 R11: fffff5200090bf1d R12: 1ffff9200090bf51
R13: dffffc0000000000 R14: 1ffff9200090bf4c R15: 1ffff9200090bf4c
FS:  000055558f285500(0000) GS:ffff8881a3c13000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000001a000 CR3: 0000000023030000 CR4: 00000000000006f0
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: 0033:0x7fddfa38eba9
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:00007ffc7e0620f8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007fddfa5d7da0 RCX: 00007fddfa38eba9
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007fddfa5d7da0 R08: 0000000000000108 R09: 0000000f7e0623ef
R10: 00007fddfa5d7cb0 R11: 0000000000000246 R12: 00000000000254f2
R13: 00007fddfa5d6090 R14: ffffffffffffffff R15: 00007ffc7e062210
 </TASK>
