WARNING in mce_timer_fn

Status: upstream: reported C repro on 2026/07/31 17:16
Subsystems: edac
Labels: prio:normal
[Documentation on labels]
Reported-by: syzbot+9d17de59c48d71bd6824@syzkaller.appspotmail.com
First crash: 80d, last: 9h23m
Cause bisection: failed (error log, bisect log)
  
▶ ▼ ✨ AI Jobs (3)
ID Workflow Result Correct Bug Created Started Finished Revision
41748173 repro-c Reproduced: ✅ ❓ WARNING in mce_timer_fn 2026/10/17 08:09 2026/10/17 08:10 2026/10/17 09:29 432c0077
bbe55458 patching 💥 WARNING in mce_timer_fn 2026/10/13 20:14 2026/10/13 20:14 2026/10/13 20:55 7321cd29
c8bac80f assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ WARNING in mce_timer_fn 2026/07/31 01:58 2026/07/31 01:58 2026/07/31 02:04 aaffb173
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [edac?] WARNING in mce_timer_fn 1 (3) 2026/10/17 12:23
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 WARNING in mce_timer_fn -1 2 1d23h 2d00h 0/2 upstream: reported on 2026/10/16 21:03
▶ ▼ Last patch testing requests (4)
Created Duration User Patch Repo Result
2026/10/17 11:53 28m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 70dd4ee72eb2d5793c62e71c14e3aba78e5a4e56 report job log log
2026/09/12 17:16 22m retest repro upstream report job log log
2026/09/12 13:52 18m retest repro linux-next error job log
2026/09/10 02:01 13m retest repro upstream report job log log
▶ ▼ Cause bisection attempts (2)
Created Duration User Patch Repo Result
2026/09/05 15:11 29m bisect upstream error job log
2026/08/26 18:39 0m bisect upstream error

Sample crash report:
------------[ cut here ]------------
cpu_t != t
WARNING: arch/x86/kernel/cpu/mce/core.c:1770 at mce_timer_fn+0x289/0x2e0 arch/x86/kernel/cpu/mce/core.c:1770, CPU#0: udevd/4970
Modules linked in:
CPU: 0 UID: 0 PID: 4970 Comm: udevd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/05/2026
RIP: 0010:mce_timer_fn+0x289/0x2e0 arch/x86/kernel/cpu/mce/core.c:1770
Code: 59 00 4d 01 e4 4d 39 ec 4d 0f 47 e5 31 ff 4c 89 e6 e8 6b 40 59 00 4d 85 e4 0f 84 20 ff ff ff e9 f7 fe ff ff e8 b8 45 59 00 90 <0f> 0b 90 e9 cf fd ff ff 4c 89 f6 48 c7 c7 a0 ef bf 8f e8 60 dc 84
RSP: 0018:ffffc90000007c20 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8880b8223440 RCX: 0000000000000100
RDX: ffff88807cbccb00 RSI: ffffffff81b311b8 RDI: ffffffff8e6af920
RBP: ffff8880b8323440 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000000
R13: 0000000000000100 R14: 1ffff92000000f8d R15: ffffffff81b30f30
FS:  00007fa1f48b4880(0000) GS:ffff888122946000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000563a7ab14be0 CR3: 000000007be29000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 call_timer_fn+0x198/0x5f0 kernel/time/timer.c:1748
 expire_timers kernel/time/timer.c:1799 [inline]
 __run_timers+0x757/0xb00 kernel/time/timer.c:2374
 __run_timer_base kernel/time/timer.c:2386 [inline]
 __run_timer_base kernel/time/timer.c:2378 [inline]
 run_timer_base+0x114/0x190 kernel/time/timer.c:2395
 run_timer_softirq+0x10/0x50 kernel/time/timer.c:2403
 handle_softirqs+0x1e6/0x9d0 kernel/softirq.c:645
 __do_softirq kernel/softirq.c:679 [inline]
 invoke_softirq kernel/softirq.c:519 [inline]
 __irq_exit_rcu+0x16a/0x210 kernel/softirq.c:758
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:775
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
 sysvec_apic_timer_interrupt+0xa3/0xc0 arch/x86/kernel/apic/apic.c:1062
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:26 [inline]
RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:109 [inline]
RIP: 0010:arch_local_irq_save arch/x86/include/asm/irqflags.h:127 [inline]
RIP: 0010:lock_acquire kernel/locking/lockdep.c:5938 [inline]
RIP: 0010:lock_acquire+0x166/0x380 kernel/locking/lockdep.c:5899
Code: d5 00 00 00 65 8b 05 61 63 a6 13 85 c0 0f 85 c6 00 00 00 65 48 8b 05 91 1c a6 13 8b 90 a4 0b 00 00 85 d2 0f 85 b0 00 00 00 9c <8f> 04 24 fa 48 c7 c7 49 a7 4d 8e e8 6a 07 ed 09 45 89 e8 44 89 f6
RSP: 0018:ffffc90004e9f578 EFLAGS: 00000246
RAX: ffff88807cbccb00 RBX: 0000000000000000 RCX: 0000000000000001
RDX: 0000000000000000 RSI: ffffffff81b9c261 RDI: fffffbfff1fbd8bc
RBP: ffffffff8fdec5e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000200 R11: 000000000000b9e5 R12: 0000000000000002
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 rcu_read_lock include/linux/rcupdate.h:849 [inline]
 class_rcu_constructor include/linux/rcupdate.h:1216 [inline]
 unwind_next_frame+0xd1/0x2090 arch/x86/kernel/unwind_orc.c:495
 __unwind_start+0x3cd/0x7e0 arch/x86/kernel/unwind_orc.c:787
 unwind_start arch/x86/include/asm/unwind.h:64 [inline]
 arch_stack_walk+0x73/0xf0 arch/x86/kernel/stacktrace.c:24
 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:409 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:426
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5414 [inline]
 __kmalloc_noprof+0x32f/0x840 mm/slub.c:5439
 _kmalloc_noprof include/linux/slab.h:995 [inline]
 tomoyo_realpath_from_path+0xb6/0x690 security/tomoyo/realpath.c:251
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x276/0x460 security/tomoyo/file.c:827
 security_inode_getattr+0x116/0x280 security/security.c:1895
 vfs_getattr fs/stat.c:259 [inline]
 vfs_fstat+0x4b/0xe0 fs/stat.c:281
 __do_sys_newfstat+0x8b/0x110 fs/stat.c:551
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa1f4111ad7
Code: 73 01 c3 48 8b 0d 21 f3 0d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 05 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 8b 15 f1 f2 0d 00 f7 d8 64 89 02 b8
RSP: 002b:00007ffe5cd40ab8 EFLAGS: 00000206 ORIG_RAX: 0000000000000005
RAX: ffffffffffffffda RBX: 000000000000000d RCX: 00007fa1f4111ad7
RDX: 0000000000090800 RSI: 00007ffe5cd40ac0 RDI: 000000000000000d
RBP: 00007ffe5cd40ac0 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000206 R12: 00005592845d9170
R13: 00000000000000ff R14: 000055926871bbe0 R15: 00007ffe5cd40e10
 </TASK>
----------------
Code disassembly (best guess):
   0:	d5 00 00 00          	{rex2 0x0} add %al,(%rax)
   4:	65 8b 05 61 63 a6 13 	mov    %gs:0x13a66361(%rip),%eax        # 0x13a6636c
   b:	85 c0                	test   %eax,%eax
   d:	0f 85 c6 00 00 00    	jne    0xd9
  13:	65 48 8b 05 91 1c a6 	mov    %gs:0x13a61c91(%rip),%rax        # 0x13a61cac
  1a:	13
  1b:	8b 90 a4 0b 00 00    	mov    0xba4(%rax),%edx
  21:	85 d2                	test   %edx,%edx
  23:	0f 85 b0 00 00 00    	jne    0xd9
  29:	9c                   	pushf
* 2a:	8f 04 24             	pop    (%rsp) <-- trapping instruction
  2d:	fa                   	cli
  2e:	48 c7 c7 49 a7 4d 8e 	mov    $0xffffffff8e4da749,%rdi
  35:	e8 6a 07 ed 09       	call   0x9ed07a4
  3a:	45 89 e8             	mov    %r13d,%r8d
  3d:	44 89 f6             	mov    %r14d,%esi

Crashes (37):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/17 12:22 git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 70dd4ee72eb2 508909ea .config console log report C ci-upstream-kasan-gce-selinux-root WARNING in mce_timer_fn
2026/08/11 06:28 upstream d58772d8520c 508909ea .config strace log report syz / log [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in mce_timer_fn
2026/08/10 08:17 upstream db2ddb871435 5d63f80b .config console log report syz / log [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in mce_timer_fn
2026/07/30 14:05 linux-next cc2b5f627e8c 2377cd3d .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING in mce_timer_fn
2026/10/18 11:41 upstream 32c52ec87d62 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root WARNING in mce_timer_fn
2026/10/18 11:38 upstream 32c52ec87d62 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root WARNING in mce_timer_fn
2026/10/18 11:38 upstream 32c52ec87d62 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root WARNING in mce_timer_fn
2026/10/18 11:37 upstream 32c52ec87d62 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root WARNING in mce_timer_fn
2026/10/17 10:17 upstream 70dd4ee72eb2 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in mce_timer_fn
2026/10/17 05:51 upstream 70dd4ee72eb2 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root WARNING in mce_timer_fn
2026/10/16 15:11 upstream 2f2f7eeef8b0 b1757810 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in mce_timer_fn
2026/10/16 15:09 upstream 2f2f7eeef8b0 b1757810 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in mce_timer_fn
2026/10/16 15:06 upstream 2f2f7eeef8b0 b1757810 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in mce_timer_fn
2026/10/16 15:06 upstream 2f2f7eeef8b0 b1757810 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in mce_timer_fn
2026/10/16 15:06 upstream 2f2f7eeef8b0 b1757810 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in mce_timer_fn
2026/10/16 15:04 upstream 2f2f7eeef8b0 b1757810 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in mce_timer_fn
2026/10/16 15:04 upstream 2f2f7eeef8b0 b1757810 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in mce_timer_fn
2026/10/16 15:04 upstream 2f2f7eeef8b0 b1757810 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in mce_timer_fn
2026/10/16 15:03 upstream 2f2f7eeef8b0 b1757810 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in mce_timer_fn
2026/10/16 14:59 upstream 2f2f7eeef8b0 b1757810 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in mce_timer_fn
2026/10/16 14:51 upstream 2f2f7eeef8b0 b1757810 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in mce_timer_fn
2026/10/16 14:51 upstream 2f2f7eeef8b0 b1757810 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in mce_timer_fn
2026/08/27 01:50 upstream 73e3f0710014 a2b77b9e .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto WARNING in mce_timer_fn
2026/08/17 08:11 upstream dcb68831eac7 746171ee .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in mce_timer_fn
2026/07/30 14:30 upstream 11028ab62899 2377cd3d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root WARNING in mce_timer_fn
2026/07/30 10:35 upstream 11028ab62899 2377cd3d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root WARNING in mce_timer_fn
2026/07/30 10:33 upstream 11028ab62899 2377cd3d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root WARNING in mce_timer_fn
2026/08/20 03:38 upstream bd5f485f3f02 1e72964b .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in mce_timer_fn
2026/10/16 15:48 upstream 2f2f7eeef8b0 b1757810 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in mce_timer_fn
2026/10/16 13:04 upstream 2f2f7eeef8b0 b1757810 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in mce_timer_fn
2026/10/16 13:03 upstream 2f2f7eeef8b0 b1757810 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in mce_timer_fn
2026/10/16 13:02 upstream 2f2f7eeef8b0 b1757810 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in mce_timer_fn
2026/07/30 12:40 upstream 11028ab62899 abc81b93 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in mce_timer_fn
2026/07/30 12:39 upstream 11028ab62899 abc81b93 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in mce_timer_fn
2026/08/17 23:25 linux-next 4477a78374a5 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING in mce_timer_fn
2026/07/30 12:51 linux-next cc2b5f627e8c 2377cd3d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING in mce_timer_fn
2026/07/30 12:24 linux-next cc2b5f627e8c 2377cd3d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING in mce_timer_fn
* Struck through repros no longer work on HEAD.