syzbot


WARNING: locking bug in kvm_xen_set_evtchn_fast

Status: upstream: reported C repro on 2024/11/21 15:03
Subsystems: kvm-x86 kvm
[Documentation on labels]
Reported-by: syzbot+919877893c9d28162dc2@syzkaller.appspotmail.com
First crash: 420d, last: 13d
Cause bisection: introduced by (bisect log) :
commit 560af5dc839eef08a273908f390cfefefb82aa04
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Wed Oct 9 15:45:03 2024 +0000

  lockdep: Enable PROVE_RAW_LOCK_NESTING with PROVE_LOCKING.

Crash: WARNING: locking bug in kvm_xen_set_evtchn_fast (log)
Repro: C syz .config
  
Discussions (18)
Title Replies (including bot) Last reply
[syzbot] Monthly kvm report (Jan 2026) 0 (1) 2026/01/12 08:40
[syzbot] Monthly kvm-x86 report (Dec 2025) 0 (1) 2025/12/26 07:48
[syzbot] Monthly kvm report (Dec 2025) 0 (1) 2025/12/11 05:58
[syzbot] Monthly kvm-x86 report (Nov 2025) 0 (1) 2025/11/25 08:46
[syzbot] Monthly kvm report (Nov 2025) 0 (1) 2025/11/10 09:15
[syzbot] Monthly kvm-x86 report (Oct 2025) 0 (1) 2025/10/24 18:48
[syzbot] Monthly kvm report (Oct 2025) 0 (1) 2025/10/10 07:32
[syzbot] Monthly kvm-x86 report (Sep 2025) 0 (1) 2025/09/15 12:33
[syzbot] Monthly kvm report (Sep 2025) 0 (1) 2025/09/01 07:38
[syzbot] Monthly kvm report (Jul 2025) 0 (1) 2025/07/31 08:59
[syzbot] Monthly kvm-x86 report (Jul 2025) 0 (1) 2025/07/08 08:12
[syzbot] Monthly kvm-x86 report (Jun 2025) 0 (1) 2025/06/08 17:33
[syzbot] Monthly kvm report (May 2025) 0 (1) 2025/05/12 13:34
[syzbot] Monthly kvm report (Apr 2025) 0 (1) 2025/04/02 09:38
[syzbot] Monthly kvm report (Feb 2025) 0 (1) 2025/02/11 13:32
[syzbot] Monthly kvm report (Jan 2025) 0 (1) 2025/01/13 10:54
[syzbot] Monthly kvm report (Dec 2024) 0 (1) 2024/12/11 11:27
[syzbot] [kvm?] WARNING: locking bug in kvm_xen_set_evtchn_fast 4 (7) 2024/11/26 16:26
Last patch testing requests (5)
Created Duration User Patch Repo Result
2025/12/26 01:41 15m retest repro upstream report log
2025/12/04 23:42 43m retest repro upstream report log
2025/11/08 10:31 24m retest repro upstream report log
2025/11/08 10:31 15m retest repro upstream report log
2025/08/28 20:13 14m retest repro upstream report log

Sample crash report:
=============================
[ BUG: Invalid wait context ]
syzkaller #0 Not tainted
-----------------------------
swapper/1/0 is trying to lock:
ffff88807e7552e0 (&gpc->lock){....}-{3:3}, at: kvm_xen_set_evtchn_fast+0x1fb/0x9b0 arch/x86/kvm/xen.c:1820
other info that might help us debug this:
context-{2:2}
1 lock held by swapper/1/0:
 #0: ffff88807e755838 (&kvm->srcu){.?.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:185 [inline]
 #0: ffff88807e755838 (&kvm->srcu){.?.+}-{0:0}, at: srcu_read_lock include/linux/srcu.h:277 [inline]
 #0: ffff88807e755838 (&kvm->srcu){.?.+}-{0:0}, at: kvm_xen_set_evtchn_fast+0x1c3/0x9b0 arch/x86/kvm/xen.c:1818
stack backtrace:
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <IRQ>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_lock_invalid_wait_context kernel/locking/lockdep.c:4830 [inline]
 check_wait_context kernel/locking/lockdep.c:4902 [inline]
 __lock_acquire+0xec2/0x2cf0 kernel/locking/lockdep.c:5187
 lock_acquire+0x107/0x340 kernel/locking/lockdep.c:5868
 __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline]
 _raw_read_lock_irqsave+0x48/0x60 kernel/locking/spinlock.c:236
 kvm_xen_set_evtchn_fast+0x1fb/0x9b0 arch/x86/kvm/xen.c:1820
 xen_timer_callback+0x109/0x220 arch/x86/kvm/xen.c:140
 __run_hrtimer kernel/time/hrtimer.c:1777 [inline]
 __hrtimer_run_queues+0x4d0/0xc30 kernel/time/hrtimer.c:1841
 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1903
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline]
 __sysvec_apic_timer_interrupt+0x102/0x3e0 arch/x86/kernel/apic/apic.c:1062
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
 sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1056
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:82
Code: 13 e3 02 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 73 c1 0e 00 f3 0f 1e fa fb f4 <c3> cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc90000197e20 EFLAGS: 000002c2
RAX: 0000000000064249 RBX: ffffffff819713ee RCX: 0000000080000001
RDX: 0000000000000001 RSI: ffffffff8d79207b RDI: ffffffff8bc083e0
RBP: ffffc90000197f10 R08: ffff8880b87336db R09: 1ffff110170e66db
R10: dffffc0000000000 R11: ffffed10170e66dc R12: ffffffff8f822270
R13: 1ffff110038d4b70 R14: 0000000000000001 R15: 0000000000000001
 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:767
 default_idle_call+0x73/0xb0 kernel/sched/idle.c:122
 cpuidle_idle_call kernel/sched/idle.c:191 [inline]
 do_idle+0x1be/0x4d0 kernel/sched/idle.c:332
 cpu_startup_entry+0x44/0x60 kernel/sched/idle.c:430
 start_secondary+0x101/0x110 arch/x86/kernel/smpboot.c:312
 common_startup_64+0x13e/0x147
 </TASK>
----------------
Code disassembly (best guess):
   0:	13 e3                	adc    %ebx,%esp
   2:	02 00                	add    (%rax),%al
   4:	cc                   	int3
   5:	cc                   	int3
   6:	cc                   	int3
   7:	90                   	nop
   8:	90                   	nop
   9:	90                   	nop
   a:	90                   	nop
   b:	90                   	nop
   c:	90                   	nop
   d:	90                   	nop
   e:	90                   	nop
   f:	90                   	nop
  10:	90                   	nop
  11:	90                   	nop
  12:	90                   	nop
  13:	90                   	nop
  14:	90                   	nop
  15:	90                   	nop
  16:	90                   	nop
  17:	f3 0f 1e fa          	endbr64
  1b:	66 90                	xchg   %ax,%ax
  1d:	0f 00 2d 73 c1 0e 00 	verw   0xec173(%rip)        # 0xec197
  24:	f3 0f 1e fa          	endbr64
  28:	fb                   	sti
  29:	f4                   	hlt
* 2a:	c3                   	ret <-- trapping instruction
  2b:	cc                   	int3
  2c:	cc                   	int3
  2d:	cc                   	int3
  2e:	cc                   	int3
  2f:	cc                   	int3
  30:	cc                   	int3
  31:	cc                   	int3
  32:	cc                   	int3
  33:	cc                   	int3
  34:	cc                   	int3
  35:	cc                   	int3
  36:	cc                   	int3
  37:	90                   	nop
  38:	90                   	nop
  39:	90                   	nop
  3a:	90                   	nop
  3b:	90                   	nop
  3c:	90                   	nop
  3d:	90                   	nop
  3e:	90                   	nop
  3f:	90                   	nop

Crashes (660):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/01 18:08 upstream b69053dd3ffb d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING: locking bug in kvm_xen_set_evtchn_fast
2024/11/23 13:17 upstream 06afb0f36106 68da6d95 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/12/12 01:00 upstream d358e5254674 d1b870e1 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/03/04 11:39 upstream 99fa936e8e4f c3901742 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/06/14 19:37 upstream 4774cfe3543a 5f4b362d .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/10/22 00:15 upstream 6548d364a3e8 9832ed61 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/10/12 22:44 upstream 8765f467912f ff1712fe .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/09/29 07:25 upstream 8f9736633f8c 001c9061 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/09/21 01:05 upstream 3b08f56fbbb9 67c37560 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/09/20 02:50 upstream 097a6c336d00 67c37560 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/09/09 18:44 upstream f777d1112ee5 d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/09/09 11:39 upstream f777d1112ee5 d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/08/07 00:37 upstream 479058002c32 4bd24a3e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/07/23 03:55 upstream 89be9a83ccf1 85deaf45 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/06/22 14:49 upstream 739a6c93cc75 d6cdfb8a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/05/30 08:27 upstream e0797d3b91de 3d2f584d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/06/05 03:19 upstream 1af80d00e1e0 fd5e6e61 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/11/20 21:22 upstream 8e621c9a3375 2cc4c24a .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/11/09 01:16 upstream 7bb4d6512545 4e1406b4 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/10/25 10:30 upstream d2818517e348 c0460fcd .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/10/18 05:25 upstream 6f3b6e91f720 1c8c8cd8 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/10/17 04:15 upstream 634ec1fc7982 19568248 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/10/16 11:55 upstream 7ea30958b305 19568248 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/09/16 11:47 upstream 46a51f4f5eda e2beed91 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/09/15 14:38 upstream f83ec76bf285 e2beed91 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/09/15 02:51 upstream 79e8447ec662 e2beed91 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/09/09 13:26 upstream f777d1112ee5 d291dd2d .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/09/06 13:47 upstream d1d10cea0895 d291dd2d .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/09/01 16:11 upstream b320789d6883 807a3b61 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/08/14 20:00 upstream 0cc53520e68b dcc075fb .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/08/11 02:56 upstream 2b38afce25c4 32a0e5ed .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/08/06 13:23 upstream 479058002c32 4bd24a3e .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/08/04 16:00 upstream d2eedaa3909b abdcb213 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/07/29 10:18 upstream ced1b9e0392d c4a95487 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/07/29 06:20 upstream ced1b9e0392d c4a95487 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/07/28 15:29 upstream 038d61fd6422 6654ea9c .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/07/27 14:54 upstream ec2df4364666 fb8f743d .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/07/23 04:57 upstream 89be9a83ccf1 e1dd4f22 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/07/20 00:37 upstream bf61759db409 7117feec .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/07/15 01:06 upstream 347e9f5043c8 03fcfc4b .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/07/13 02:22 upstream 3f31a806a62e 3cda49cf .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/07/07 09:01 upstream 772b78c2abd8 4f67c4ae .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/07/06 09:59 upstream 1f988d0788f5 4f67c4ae .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/07/04 20:59 upstream c435a4f487e8 d869b261 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/07/04 16:10 upstream 4c06e63b9203 d869b261 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/06/25 08:20 upstream 7595b66ae9de 26d77996 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/06/24 12:56 upstream 78f4e737a53e e2f27c35 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING: locking bug in kvm_xen_set_evtchn_fast
2024/11/21 10:38 upstream 8f7c8b88bda4 4b25d554 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING: locking bug in kvm_xen_set_evtchn_fast
2024/11/21 04:53 upstream 8f7c8b88bda4 4b25d554 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/08/07 08:49 upstream cca7a0aae895 9a42d6b1 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/09/23 17:05 linux-next 846bd2225ec3 0ac7291c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/09/19 10:54 linux-next ae2d20002576 e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/09/14 05:39 linux-next 590b221ed425 e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/08/11 22:32 linux-next b1549501188c 32a0e5ed .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/08/08 16:38 linux-next b1549501188c 987b750d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/08/08 13:58 linux-next b1549501188c 987b750d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/08/08 09:44 linux-next b1549501188c 6a893178 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/08/07 23:25 linux-next 442d93313cae 04cffc22 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/08/07 21:25 linux-next 442d93313cae 04cffc22 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/08/07 17:53 linux-next 442d93313cae 04cffc22 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/08/07 16:22 linux-next 442d93313cae 04cffc22 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/08/07 16:21 linux-next 442d93313cae 04cffc22 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING: locking bug in kvm_xen_set_evtchn_fast
2025/07/22 15:04 linux-next d086c886ceb9 1555463b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root WARNING: locking bug in kvm_xen_set_evtchn_fast
* Struck through repros no longer work on HEAD.