WARNING in mce_timer_fn

Status: upstream: reported syz repro on 2026/07/31 17:16
Subsystems: edac
Labels: prio:normal
[Documentation on labels]
Reported-by: syzbot+9d17de59c48d71bd6824@syzkaller.appspotmail.com
First crash: 3d06h, last: 3d02h
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
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 (2) 2026/07/31 18:23

Sample crash report:
------------[ cut here ]------------
cpu_t != t
WARNING: arch/x86/kernel/cpu/mce/core.c:1770 at mce_timer_fn+0x23f/0x280 arch/x86/kernel/cpu/mce/core.c:1770, CPU#0: ktimers/0/16
Modules linked in:
CPU: 0 UID: 0 PID: 16 Comm: ktimers/0 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:mce_timer_fn+0x23f/0x280 arch/x86/kernel/cpu/mce/core.c:1770
Code: 00 75 0a e8 93 3b 55 00 e9 16 ff ff ff e8 89 3b 55 00 4c 8b 1d f2 b1 af 0c 2e 2e 2e 41 ff d3 e9 ff fe ff ff e8 72 3b 55 00 90 <0f> 0b 90 e9 33 fe ff ff e8 64 3b 55 00 48 c7 c7 a0 20 20 8e 4c 89
RSP: 0018:ffffc90000157a08 EFLAGS: 00010246
RAX: ffffffff8170683e RBX: ffff8880b87234a0 RCX: ffff88801daf8000
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000100
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000100
R10: dffffc0000000000 R11: ffffffff81706600 R12: 0000000000000000
R13: dffffc0000000000 R14: ffffffff8dc427d0 R15: ffff8880b87234a0
FS:  0000000000000000(0000) GS:ffff8881259f2000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f08d99b56c8 CR3: 000000003fe3e000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748
 expire_timers kernel/time/timer.c:1799 [inline]
 __run_timers kernel/time/timer.c:2374 [inline]
 __run_timer_base+0x67b/0x9b0 kernel/time/timer.c:2386
 run_timer_base kernel/time/timer.c:2395 [inline]
 run_timer_softirq+0x67/0x170 kernel/time/timer.c:2403
 handle_softirqs+0x1d9/0x6c0 kernel/softirq.c:626
 __do_softirq kernel/softirq.c:660 [inline]
 run_ktimerd+0x69/0x100 kernel/softirq.c:1155
 smpboot_thread_fn+0x57c/0xa80 kernel/smpboot.c:160
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Crashes (8):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
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
2026/07/30 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
2026/07/30 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
2026/07/30 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.