syzbot
WARNING: ODEBUG bug in mcheck_cpu_init
Status:
moderation: reported on 2026/10/09 13:58
Subsystems:
edac
Labels:
prio:low
[Documentation on labels]
Reported-by: syzbot+fcc0b3f9f99f26c710d7@syzkaller.appspotmail.com
First crash: 6d19h, last: 1d04h
Sample crash report:
------------[ cut here ]------------
ODEBUG: init active (active state 0) object: ffff8880b85234a0 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 Tainted: G S L syzkaller #0 PREEMPT_{RT,(full)}
Tainted: [S]=CPU_OUT_OF_SPEC, [L]=SOFTLOCKUP
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 8d a7 58 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 23 54 d7 0b 48 83 c4 10 5b 41 5c
RSP: 0000:ffffc900001d7c20 EFLAGS: 00010046
RAX: 1ffffffff16df3c0 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: ffffffff8bcc7840 RSI: ffffffff8bcc7440 RDI: ffffffff90bccf10
RBP: ffffffff8bcc7840 R08: ffff8880b85234a0 R09: ffffffff8b6fb180
R10: dffffc0000000000 R11: ffffffff81b2b610 R12: 0000000000000000
R13: ffffffff90bccf10 R14: ffff8880b85234a0 R15: ffffffff8b6f9e00
FS: 0000000000000000(0000) GS:ffff888124abb000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000000efb0000 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:2262
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 8d a7 58 fd call 0xfd58a7a0
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 23 54 d7 0b incl 0xbd75423(%rip) # 0xbd7545c
39: 48 83 c4 10 add $0x10,%rsp
3d: 5b pop %rbx
3e: 41 5c pop %r12
* Struck through repros no longer work on HEAD.