general protection fault in __io_wq_cpu

Kernel	Title	Rank 🛈	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
linux-5.15	general protection fault in __io_wq_cpu_online	2				1	46d	46d	0/3	upstream: reported on 2026/08/04 05:57
kvm-guest: stealtime: cpu 1, msr 1f7127040
general protection fault, probably for non-canonical address 0xdffffc000000000d: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000068-0x000000000000006f]
CPU: 1 PID: 22 Comm: cpuhp/1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:io_wq_for_each_worker io_uring/io-wq.c:860 [inline]
RIP: 0010:__io_wq_cpu_online+0x55/0x1d0 io_uring/io-wq.c:1326
Code: 0a ff 49 83 c7 60 4c 89 f8 48 c1 e8 03 42 80 3c 30 00 74 08 4c 89 ff e8 89 1c 5c ff 4d 8b 3f 49 83 c7 68 4c 89 f8 48 c1 e8 03 <42> 80 3c 30 00 74 08 4c 89 ff e8 6c 1c 5c ff 4d 8b 27 4d 39 fc 0f
RSP: 0000:ffffc90000177d08 EFLAGS: 00010202
RAX: 000000000000000d RBX: 0000000000000001 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff88812bb5a000
RBP: ffffc90000177d48 R08: ffff8881f71271a0 R09: 0000000000000002
R10: 0000000000000002 R11: 0000000000000000 R12: 00000000000000e8
R13: ffff88812bb5a048 R14: dffffc0000000000 R15: 0000000000000068
FS:  0000000000000000(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000000660f000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 io_wq_cpu_online+0x2a/0x40 io_uring/io-wq.c:1335
 cpuhp_invoke_callback+0x352/0xed0 kernel/cpu.c:214
 cpuhp_thread_fun+0x36b/0x6b0 kernel/cpu.c:823
 smpboot_thread_fn+0x446/0x880 kernel/smpboot.c:164
 kthread+0x3f5/0x4f0 kernel/kthread.c:337
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
Modules linked in:
---[ end trace 302a85e23554603f ]---
RIP: 0010:io_wq_for_each_worker io_uring/io-wq.c:860 [inline]
RIP: 0010:__io_wq_cpu_online+0x55/0x1d0 io_uring/io-wq.c:1326
Code: 0a ff 49 83 c7 60 4c 89 f8 48 c1 e8 03 42 80 3c 30 00 74 08 4c 89 ff e8 89 1c 5c ff 4d 8b 3f 49 83 c7 68 4c 89 f8 48 c1 e8 03 <42> 80 3c 30 00 74 08 4c 89 ff e8 6c 1c 5c ff 4d 8b 27 4d 39 fc 0f
RSP: 0000:ffffc90000177d08 EFLAGS: 00010202
RAX: 000000000000000d RBX: 0000000000000001 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff88812bb5a000
RBP: ffffc90000177d48 R08: ffff8881f71271a0 R09: 0000000000000002
R10: 0000000000000002 R11: 0000000000000000 R12: 00000000000000e8
R13: ffff88812bb5a048 R14: dffffc0000000000 R15: 0000000000000068
FS:  0000000000000000(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000000660f000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	0a ff                	or     %bh,%bh
   2:	49 83 c7 60          	add    $0x60,%r15
   6:	4c 89 f8             	mov    %r15,%rax
   9:	48 c1 e8 03          	shr    $0x3,%rax
   d:	42 80 3c 30 00       	cmpb   $0x0,(%rax,%r14,1)
  12:	74 08                	je     0x1c
  14:	4c 89 ff             	mov    %r15,%rdi
  17:	e8 89 1c 5c ff       	call   0xff5c1ca5
  1c:	4d 8b 3f             	mov    (%r15),%r15
  1f:	49 83 c7 68          	add    $0x68,%r15
  23:	4c 89 f8             	mov    %r15,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 80 3c 30 00       	cmpb   $0x0,(%rax,%r14,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	4c 89 ff             	mov    %r15,%rdi
  34:	e8 6c 1c 5c ff       	call   0xff5c1ca5
  39:	4d 8b 27             	mov    (%r15),%r12
  3c:	4d 39 fc             	cmp    %r15,%r12
  3f:	0f                   	.byte 0xf