* [syzbot] [kvm-x86?] WARNING in hv_tlb_flush_enqueue
@ 2026-06-22 17:01 syzbot
2026-06-23 0:12 ` Sean Christopherson
0 siblings, 1 reply; 3+ messages in thread
From: syzbot @ 2026-06-22 17:01 UTC (permalink / raw)
To: bp, dave.hansen, hpa, kvm, linux-kernel, mingo, pbonzini, seanjc,
syzkaller-bugs, tglx, x86
Hello,
syzbot found the following issue on:
HEAD commit: 8cd8cf7a07e5 Merge tag 'scsi-misc' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1012a7a1580000
kernel config: https://syzkaller.appspot.com/x/.config?x=e69294ccc24d9da
dashboard link: https://syzkaller.appspot.com/bug?extid=5d2b94b77112148d1744
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14c0db7a580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13dd001c580000
Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-8cd8cf7a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b15ef084e059/vmlinux-8cd8cf7a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a22f25c3f8ee/bzImage-8cd8cf7a.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5d2b94b77112148d1744@syzkaller.appspotmail.com
------------[ 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
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [syzbot] [kvm-x86?] WARNING in hv_tlb_flush_enqueue
2026-06-22 17:01 [syzbot] [kvm-x86?] WARNING in hv_tlb_flush_enqueue syzbot
@ 2026-06-23 0:12 ` Sean Christopherson
2026-06-23 0:42 ` syzbot
0 siblings, 1 reply; 3+ messages in thread
From: Sean Christopherson @ 2026-06-23 0:12 UTC (permalink / raw)
To: syzbot
Cc: bp, dave.hansen, hpa, kvm, linux-kernel, mingo, pbonzini,
syzkaller-bugs, tglx, x86
On Mon, Jun 22, 2026, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 8cd8cf7a07e5 Merge tag 'scsi-misc' of git://git.kernel.org..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1012a7a1580000
> kernel config: https://syzkaller.appspot.com/x/.config?x=e69294ccc24d9da
> dashboard link: https://syzkaller.appspot.com/bug?extid=5d2b94b77112148d1744
> compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14c0db7a580000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13dd001c580000
>
> Downloadable assets:
> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-8cd8cf7a.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/b15ef084e059/vmlinux-8cd8cf7a.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/a22f25c3f8ee/bzImage-8cd8cf7a.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+5d2b94b77112148d1744@syzkaller.appspotmail.com
>
> ------------[ 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
>
>
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
>
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
>
> If the report is already addressed, let syzbot know by replying with:
> #syz fix: exact-commit-title
>
> If you want syzbot to run the reproducer, reply with:
> #syz test: git://repo/address.git branch-or-commit-hash
> If you attach or paste a git patch, syzbot will apply it before testing.
>
> If you want to overwrite report's subsystems, reply with:
> #syz set subsystems: new-subsystem
> (See the list of subsystem names on the web dashboard)
>
> If the report is a duplicate of another one, reply with:
> #syz dup: exact-subject-of-another-report
>
> If you want to undo deduplication, reply with:
> #syz undup
#syz test: https://github.com/sean-jc/linux.git aec262d23f20702b3fd317bf67d470499daba87a
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [syzbot] [kvm-x86?] WARNING in hv_tlb_flush_enqueue
2026-06-23 0:12 ` Sean Christopherson
@ 2026-06-23 0:42 ` syzbot
0 siblings, 0 replies; 3+ messages in thread
From: syzbot @ 2026-06-23 0:42 UTC (permalink / raw)
To: bp, dave.hansen, hpa, kvm, linux-kernel, mingo, pbonzini, seanjc,
syzkaller-bugs, tglx, x86
Hello,
syzbot has tested the proposed patch and the reproducer did not trigger any issue:
Reported-by: syzbot+5d2b94b77112148d1744@syzkaller.appspotmail.com
Tested-by: syzbot+5d2b94b77112148d1744@syzkaller.appspotmail.com
Tested on:
commit: aec262d2 KVM: x86/hyperv: Ensure vCPU's Hyper-V object..
git tree: https://github.com/sean-jc/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=167b177a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=79a99f123f20da7b
dashboard link: https://syzkaller.appspot.com/bug?extid=5d2b94b77112148d1744
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
Note: no patches were applied.
Note: testing is done by a robot and is best-effort only.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2026-06-23 0:42 UTC | newest]
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2026-06-22 17:01 [syzbot] [kvm-x86?] WARNING in hv_tlb_flush_enqueue syzbot
2026-06-23 0:12 ` Sean Christopherson
2026-06-23 0:42 ` syzbot
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