------------[ cut here ]------------
failed to allocate ring buffer on CPU 3
WARNING: kernel/trace/ring_buffer.c:7976 at trace_rb_cpu_prepare+0x458/0x500 kernel/trace/ring_buffer.c:7976, CPU#1: syz.6.821/9626
Modules linked in:
CPU: 1 UID: 0 PID: 9626 Comm: syz.6.821 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:trace_rb_cpu_prepare+0x45a/0x500 kernel/trace/ring_buffer.c:7976
Code: 48 c1 ea 03 80 3c 02 00 0f 84 c7 fc ff ff 48 8b 3c 24 e8 29 12 6c 00 e9 b9 fc ff ff e8 ff 83 fb ff 48 8d 3d d8 d6 16 0f 89 ee <67> 48 0f b9 3a bb f4 ff ff ff e9 df fd ff ff 4c 89 ef e8 ff 11 6c
RSP: 0018:ffffc900066bf8c0 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff888055e470b8 RCX: ffff888033b7dd98
RDX: ffff8880574a0000 RSI: 0000000000000003 RDI: ffffffff9125b7c0
RBP: 0000000000000003 R08: ffff888033b7dd98 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000003
R13: ffff888055e47010 R14: 0000000000000018 R15: 0000000000000162
FS:  00007fa815fd16c0(0000) GS:ffff8880d5eec000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa815f8eff8 CR3: 0000000038cf3000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 cpuhp_invoke_callback+0x205/0x9a0 kernel/cpu.c:204
 cpuhp_issue_call+0x1b8/0x970 kernel/cpu.c:2354
 __cpuhp_state_add_instance_cpuslocked+0x2d7/0x400 kernel/cpu.c:2423
 __cpuhp_state_add_instance+0xd7/0x2d0 kernel/cpu.c:2444
 cpuhp_state_add_instance include/linux/cpuhotplug.h:384 [inline]
 alloc_buffer+0x76c/0x1800 kernel/trace/ring_buffer.c:2830
 __ring_buffer_alloc+0x2d/0x40 kernel/trace/ring_buffer.c:2872
 allocate_trace_buffer+0x150/0xa30 kernel/trace/trace.c:8412
 allocate_trace_buffers kernel/trace/trace.c:8445 [inline]
 trace_array_create_systems+0x582/0xc30 kernel/trace/trace.c:8623
 trace_array_create kernel/trace/trace.c:8666 [inline]
 instance_mkdir+0xca/0x140 kernel/trace/trace.c:8681
 tracefs_syscall_mkdir+0x10e/0x180 fs/tracefs/inode.c:121
 vfs_mkdir+0x361/0x850 fs/namei.c:5276
 filename_mkdirat+0x48b/0x5e0 fs/namei.c:5309
 __do_sys_mkdirat fs/namei.c:5330 [inline]
 __se_sys_mkdirat fs/namei.c:5327 [inline]
 __x64_sys_mkdirat+0x89/0xc0 fs/namei.c:5327
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa81519e0d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fa815fd1028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007fa815426090 RCX: 00007fa81519e0d9
RDX: 00000000000001ff RSI: 0000200000000600 RDI: ffffffffffffff9c
RBP: 00007fa815235024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa815426128 R14: 00007fa815426090 R15: 00007fff17be7738
 </TASK>
----------------
Code disassembly (best guess):
   0:	48 c1 ea 03          	shr    $0x3,%rdx
   4:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1)
   8:	0f 84 c7 fc ff ff    	je     0xfffffcd5
   e:	48 8b 3c 24          	mov    (%rsp),%rdi
  12:	e8 29 12 6c 00       	call   0x6c1240
  17:	e9 b9 fc ff ff       	jmp    0xfffffcd5
  1c:	e8 ff 83 fb ff       	call   0xfffb8420
  21:	48 8d 3d d8 d6 16 0f 	lea    0xf16d6d8(%rip),%rdi        # 0xf16d700
  28:	89 ee                	mov    %ebp,%esi
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	bb f4 ff ff ff       	mov    $0xfffffff4,%ebx
  34:	e9 df fd ff ff       	jmp    0xfffffe18
  39:	4c 89 ef             	mov    %r13,%rdi
  3c:	e8                   	.byte 0xe8
  3d:	ff 11                	call   *(%rcx)
  3f:	6c                   	insb   (%dx),%es:(%rdi)