------------[ cut here ]------------
WARNING: kernel/rcu/tree_stall.h:1049 at rcu_check_gp_start_stall+0x2e4/0x470 kernel/rcu/tree_stall.h:1049, CPU#0: syz.1.18/6043
Modules linked in:
CPU: 0 UID: 0 PID: 6043 Comm: syz.1.18 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:rcu_check_gp_start_stall+0x2e4/0x470 kernel/rcu/tree_stall.h:1049
Code: ff ff 48 c7 c7 80 d5 d5 99 be 04 00 00 00 e8 83 3b 80 00 4c 89 f7 b8 01 00 00 00 87 05 c5 42 2e 18 85 c0 0f 85 17 ff ff ff 90 <0f> 0b 90 48 81 ff 40 3e 34 8e 74 47 48 c7 c0 80 2d c4 8f 48 c1 e8
RSP: 0018:ffffc90000007db8 EFLAGS: 00010046
RAX: 0000000000000000 RBX: 0000000000000246 RCX: ffffffff81a792ad
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffffff8e343e40
RBP: ffffc90000007f30 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff33abab0 R12: 0000000000002904
R13: dffffc0000000000 R14: ffffffff8e343e40 R15: dffffc0000000000
FS: 0000555575d2e500(0000) GS:ffff8881259bb000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000075b74000 CR4: 00000000003526f0
Call Trace:
rcu_core+0x402/0x1060 kernel/rcu/tree.c:2864
handle_softirqs+0x22b/0x7c0 kernel/softirq.c:626
__do_softirq kernel/softirq.c:660 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0x60/0x150 kernel/softirq.c:727
irq_exit_rcu+0x9/0x30 kernel/softirq.c:743
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1056
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:vcpu_enter_guest arch/x86/kvm/x86.c:11439 [inline]
RIP: 0010:vcpu_run+0x5215/0x7670 arch/x86/kvm/x86.c:11639
Code: 4c 8b a4 24 20 01 00 00 4c 89 e3 48 c1 eb 03 42 0f b6 04 3b 84 c0 0f 85 12 10 00 00 41 c6 04 24 01 e8 2f 9e 81 00 fb 4c 89 f0 <48> c1 e8 03 42 80 3c 38 00 74 08 4c 89 f7 e8 48 a4 e0 00 49 ff 06
RSP: 0018:ffffc90002f775c0 EFLAGS: 00000202
RAX: ffff888077a79d08 RBX: 1ffff1100ef4f186 RCX: 0000000080000001
RDX: 0000000000000006 RSI: ffffffff8dab3e14 RDI: ffffffff8be259e0
RBP: ffffc90002f779b0 R08: ffffffff8fc3fd77 R09: 1ffffffff1f87fae
R10: dffffc0000000000 R11: fffffbfff1f87faf R12: ffff888077a78c32
R13: ffff888077a78000 R14: ffff888077a79d08 R15: dffffc0000000000
kvm_arch_vcpu_ioctl_run+0x1148/0x1c90 arch/x86/kvm/x86.c:11984
kvm_vcpu_ioctl+0x99a/0xed0 virt/kvm/kvm_main.c:4492
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc29298f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffcdfe28888 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fc292be5fa0 RCX: 00007fc29298f749
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
RBP: 00007fc292a13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc292be5fa0 R14: 00007fc292be5fa0 R15: 0000000000000003
----------------
Code disassembly (best guess):
0: 4c 8b a4 24 20 01 00 mov 0x120(%rsp),%r12
7: 00
8: 4c 89 e3 mov %r12,%rbx
b: 48 c1 eb 03 shr $0x3,%rbx
f: 42 0f b6 04 3b movzbl (%rbx,%r15,1),%eax
14: 84 c0 test %al,%al
16: 0f 85 12 10 00 00 jne 0x102e
1c: 41 c6 04 24 01 movb $0x1,(%r12)
21: e8 2f 9e 81 00 call 0x819e55
26: fb sti
27: 4c 89 f0 mov %r14,%rax
* 2a: 48 c1 e8 03 shr $0x3,%rax <-- trapping instruction
2e: 42 80 3c 38 00 cmpb $0x0,(%rax,%r15,1)
33: 74 08 je 0x3d
35: 4c 89 f7 mov %r14,%rdi
38: e8 48 a4 e0 00 call 0xe0a485
3d: 49 ff 06 incq (%r14)