syzbot


WARNING in hv_tlb_flush_enqueue

Status: upstream: reported C repro on 2026/06/22 17:01
Subsystems: kvm-x86
[Documentation on labels]
Reported-by: syzbot+5d2b94b77112148d1744@syzkaller.appspotmail.com
First crash: 19h14m, last: 16h52m
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
4be3193c-7052-49bc-a47e-e6d2540ca0a9 assessment-security 💥 WARNING in hv_tlb_flush_enqueue 2026/06/22 01:55 2026/06/22 01:55 2026/06/22 01:56 43bfcdb07c3552e4664e1029672054ac0924d543
failed to run ["git" "-c" "core.hooksPath=/dev/null" "checkout" "8cd8cf7a07e5d141b0c75ce6cf470630e11aa11a"]: exit status 128
Previous HEAD position was 7367539ad4b0 Merge tag 'cxl-fixes-6.9-rc7' of gi...
truncated to first 200 bytes; open job for full error
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [kvm-x86?] WARNING in hv_tlb_flush_enqueue 0 (1) 2026/06/22 17:01
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-6-12 WARNING in hv_tlb_flush_enqueue origin:upstream -1 syz 2 30d 65d 0/1 premoderation: reported syz repro on 2026/04/18 15:04

Sample crash report:
------------[ cut here ]------------
pvqspinlock: lock 0xffff88802c0c8790 has corrupted value 0x0!
WARNING: kernel/locking/qspinlock_paravirt.h:504 at __pv_queued_spin_unlock_slowpath+0x220/0x2e0 kernel/locking/qspinlock_paravirt.h:504, CPU#0: syz.0.3154/18851
Modules linked in:
CPU: 0 UID: 0 PID: 18851 Comm: syz.0.3154 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:__pv_queued_spin_unlock_slowpath+0x223/0x2e0 kernel/locking/qspinlock_paravirt.h:504
Code: fc ff df 48 c1 ea 03 0f b6 14 02 4c 89 e0 83 e0 07 83 c0 03 38 d0 7c 04 84 d2 75 4d 41 8b 14 24 48 8d 3d 40 00 44 05 4c 89 e6 <67> 48 0f b9 3a e9 2f ff ff ff 48 89 df 48 89 14 24 e8 17 07 e0 f6
RSP: 0018:ffffc9000c4273a0 EFLAGS: 00010246
RAX: 0000000000000003 RBX: ffff88802c0c8790 RCX: ffffffff8b99c87f
RDX: 0000000000000000 RSI: ffff88802c0c8790 RDI: ffffffff90ddc8f0
RBP: ffff88802c0c8798 R08: 0000000000000000 R09: ffffed10058190f2
R10: ffff88802c0c8793 R11: 0000000000000000 R12: ffff88802c0c8790
R13: ffff88802c0c8000 R14: 0000000000000000 R15: ffff88802c0c87d0
FS:  00007ffaf56696c0(0000) GS:ffff8880d6318000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000005645e000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 __raw_callee_save___pv_queued_spin_unlock_slowpath+0x15/0x40
 .slowpath+0x9/0x18
 pv_queued_spin_unlock arch/x86/include/asm/paravirt-spinlock.h:40 [inline]
 queued_spin_unlock arch/x86/include/asm/paravirt-spinlock.h:72 [inline]
 do_raw_spin_unlock+0x145/0x1e0 kernel/locking/spinlock_debug.c:142
 __raw_spin_unlock include/linux/spinlock_api_smp.h:168 [inline]
 _raw_spin_unlock+0x1e/0x50 kernel/locking/spinlock.c:190
 spin_unlock include/linux/spinlock.h:390 [inline]
 hv_tlb_flush_enqueue.isra.0+0x195/0x200 arch/x86/kvm/hyperv.c:1967
 kvm_hv_flush_tlb+0x17b4/0x1ae0 arch/x86/kvm/hyperv.c:2150
 kvm_hv_hypercall+0xd0b/0x2350 arch/x86/kvm/hyperv.c:2629
 kvm_emulate_hypercall+0x115/0x3c0 arch/x86/kvm/x86.c:10510
 __vmx_handle_exit arch/x86/kvm/vmx/vmx.c:6848 [inline]
 vmx_handle_exit+0x4d6/0x1ef0 arch/x86/kvm/vmx/vmx.c:6858
 vcpu_enter_guest arch/x86/kvm/x86.c:11550 [inline]
 vcpu_run+0x3558/0x5d50 arch/x86/kvm/x86.c:11707
 kvm_arch_vcpu_ioctl_run+0x5b6/0x1890 arch/x86/kvm/x86.c:12062
 kvm_vcpu_ioctl+0x730/0x1700 virt/kvm/kvm_main.c:4470
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ffaf479ce59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffaf5669028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ffaf4a15fa0 RCX: 00007ffaf479ce59
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000006
RBP: 00007ffaf4832e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffaf4a16038 R14: 00007ffaf4a15fa0 R15: 00007ffcc021d3a8
 </TASK>
----------------
Code disassembly (best guess), 3 bytes skipped:
   0:	48 c1 ea 03          	shr    $0x3,%rdx
   4:	0f b6 14 02          	movzbl (%rdx,%rax,1),%edx
   8:	4c 89 e0             	mov    %r12,%rax
   b:	83 e0 07             	and    $0x7,%eax
   e:	83 c0 03             	add    $0x3,%eax
  11:	38 d0                	cmp    %dl,%al
  13:	7c 04                	jl     0x19
  15:	84 d2                	test   %dl,%dl
  17:	75 4d                	jne    0x66
  19:	41 8b 14 24          	mov    (%r12),%edx
  1d:	48 8d 3d 40 00 44 05 	lea    0x5440040(%rip),%rdi        # 0x5440064
  24:	4c 89 e6             	mov    %r12,%rsi
* 27:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2c:	e9 2f ff ff ff       	jmp    0xffffff60
  31:	48 89 df             	mov    %rbx,%rdi
  34:	48 89 14 24          	mov    %rdx,(%rsp)
  38:	e8 17 07 e0 f6       	call   0xf6e00754

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/06/22 04:08 upstream 8cd8cf7a07e5 43bfcdb0 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in hv_tlb_flush_enqueue
2026/06/22 01:45 upstream 8cd8cf7a07e5 43bfcdb0 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in hv_tlb_flush_enqueue
* Struck through repros no longer work on HEAD.