Re: [syzbot] [edac?] general protection fault in detach_timer (3)

[syzbot <syzbot+edc6b57cbed1fb72d0f9@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING: ODEBUG bug in mcheck_cpu_init

------------[ cut here ]------------
ODEBUG: init active (active state 0) object: ffff8880b87234a0 object type: timer_list hint: mce_timer_fn+0x0/0x280 include/linux/highmem-internal.h:-1
WARNING: lib/debugobjects.c:632 at debug_print_object+0xec/0x230 lib/debugobjects.c:629, CPU#1: swapper/1/0
Modules linked in:
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:debug_print_object+0x18a/0x230 lib/debugobjects.c:629
Code: f8 48 c1 e8 03 80 3c 18 00 74 08 4c 89 ff e8 5d fa 59 fd 4d 8b 0f 4c 89 ef 48 8b 74 24 08 48 89 ea 44 89 e1 4d 89 f0 ff 34 24 <67> 48 0f b9 3a 48 83 c4 08 ff 05 83 7c d9 0a 48 83 c4 10 5b 41 5c
RSP: 0000:ffffc900001d7c20 EFLAGS: 00010046
RAX: 1ffffffff16df350 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: ffffffff8bcc2c40 RSI: ffffffff8bcc2840 RDI: ffffffff8fbc29e0
RBP: ffffffff8bcc2c40 R08: ffff8880b87234a0 R09: ffffffff8b6fae00
R10: dffffc0000000000 R11: ffffffff81b25c80 R12: 0000000000000000
R13: ffffffff8fbc29e0 R14: ffff8880b87234a0 R15: ffffffff8b6f9a80
FS:  0000000000000000(0000) GS:ffff888125ce1000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000000dfb0000 CR4: 00000000003506b0
Call Trace:
 <TASK>
 __debug_object_init+0x224/0x350 lib/debugobjects.c:818
 debug_timer_init kernel/time/timer.c:788 [inline]
 debug_init kernel/time/timer.c:836 [inline]
 timer_init_key+0x41/0x2c0 kernel/time/timer.c:880
 __mcheck_cpu_setup_timer arch/x86/kernel/cpu/mce/core.c:2087 [inline]
 mcheck_cpu_init+0x3dc/0x600 arch/x86/kernel/cpu/mce/core.c:2269
 identify_cpu+0x1f2c/0x3940 arch/x86/kernel/cpu/common.c:2126
 identify_secondary_cpu+0xaa/0x160 arch/x86/kernel/cpu/common.c:2187
 ap_starting+0x9c/0x150 arch/x86/kernel/smpboot.c:190
 start_secondary+0x66/0x110 arch/x86/kernel/smpboot.c:280
 common_startup_64+0x13e/0x157
 </TASK>
----------------
Code disassembly (best guess):
   0:	f8                   	clc
   1:	48 c1 e8 03          	shr    $0x3,%rax
   5:	80 3c 18 00          	cmpb   $0x0,(%rax,%rbx,1)
   9:	74 08                	je     0x13
   b:	4c 89 ff             	mov    %r15,%rdi
   e:	e8 5d fa 59 fd       	call   0xfd59fa70
  13:	4d 8b 0f             	mov    (%r15),%r9
  16:	4c 89 ef             	mov    %r13,%rdi
  19:	48 8b 74 24 08       	mov    0x8(%rsp),%rsi
  1e:	48 89 ea             	mov    %rbp,%rdx
  21:	44 89 e1             	mov    %r12d,%ecx
  24:	4d 89 f0             	mov    %r14,%r8
  27:	ff 34 24             	push   (%rsp)
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	48 83 c4 08          	add    $0x8,%rsp
  33:	ff 05 83 7c d9 0a    	incl   0xad97c83(%rip)        # 0xad97cbc
  39:	48 83 c4 10          	add    $0x10,%rsp
  3d:	5b                   	pop    %rbx
  3e:	41 5c                	pop    %r12


Tested on:

commit:         3abea627 x86/mce: Shutdown polling timer on teardown p..
git tree:       https://github.com/yutao-intel/linux.git fix-edac-v2
console output: https://syzkaller.appspot.com/x/log.txt?x=127e8779580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e618aabdc2dca7e6
dashboard link: https://syzkaller.appspot.com/bug?extid=edc6b57cbed1fb72d0f9
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

Note: no patches were applied.