------------[ cut here ]------------
failed to allocate ring buffer on CPU 2
WARNING: kernel/trace/ring_buffer.c:7976 at trace_rb_cpu_prepare+0x458/0x500 kernel/trace/ring_buffer.c:7976, CPU#0: syz.4.679/8390
Modules linked in:
CPU: 0 UID: 0 PID: 8390 Comm: syz.4.679 Not tainted syzkaller #0 PREEMPT(full) 
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 e9 0d 6c 00 e9 b9 fc ff ff e8 ff 83 fb ff 48 8d 3d b8 cf 17 0f 89 ee <67> 48 0f b9 3a bb f4 ff ff ff e9 df fd ff ff 4c 89 ef e8 bf 0d 6c
RSP: 0018:ffffc9000435f8c0 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff8880358118b8 RCX: ffff8880556de110
RDX: ffff88802b19ca80 RSI: 0000000000000002 RDI: ffffffff9126ada0
RBP: 0000000000000002 R08: ffff8880556de110 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000002
R13: ffff888035811810 R14: 0000000000000010 R15: 0000000000000162
FS:  00007f21034826c0(0000) GS:ffff8880d5dd8000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000005fe7c000 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: 0033:0x7f210259e019
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:00007f2103482028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f2102825fa0 RCX: 00007f210259e019
RDX: 00000000000001ff RSI: 0000200000000140 RDI: ffffffffffffff9c
RBP: 00007f210263500c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2102826038 R14: 00007f2102825fa0 R15: 00007ffe00e134c8
 </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 e9 0d 6c 00       	call   0x6c0e00
  17:	e9 b9 fc ff ff       	jmp    0xfffffcd5
  1c:	e8 ff 83 fb ff       	call   0xfffb8420
  21:	48 8d 3d b8 cf 17 0f 	lea    0xf17cfb8(%rip),%rdi        # 0xf17cfe0
  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:	bf                   	.byte 0xbf
  3e:	0d                   	.byte 0xd
  3f:	6c                   	insb   (%dx),%es:(%rdi)