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INFO: rcu detected stall in kvm_vcpu_ioctl

Status: upstream: reported on 2025/06/05 19:21
Reported-by: syzbot+20e139d318a0d1d22a4b@syzkaller.appspotmail.com
First crash: 172d, last: 83d
▶ ▼ Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in kvm_vcpu_ioctl (2) kvm-x86 1 1 473d 473d 0/29 auto-obsoleted due to no activity on 2024/11/06 13:35
upstream INFO: rcu detected stall in kvm_vcpu_ioctl (3) kvm-x86 1 2 268d 333d 0/29 auto-obsoleted due to no activity on 2025/05/30 15:19
upstream INFO: rcu detected stall in kvm_vcpu_ioctl mm 1 C error unreliable 251 1454d 2631d 0/29 closed as invalid on 2022/02/08 10:48
linux-4.19 INFO: rcu detected stall in kvm_vcpu_ioctl 1 C error 46 1489d 2145d 0/1 upstream: reported C repro on 2020/01/10 19:56
linux-4.14 INFO: rcu detected stall in kvm_vcpu_ioctl 1 C error 12 2046d 2203d 0/1 upstream: reported C repro on 2019/11/13 08:08
linux-4.19 BUG: soft lockup in kvm_vcpu_ioctl 1 C error 2 1667d 1670d 0/1 upstream: reported C repro on 2021/04/28 21:34
android-5-15 BUG: soft lockup in kvm_vcpu_ioctl 1 1 590d 590d 0/2 auto-obsoleted due to no activity on 2024/07/12 20:15

Sample crash report:
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (10500 ticks this GP) idle=0ef/1/0x4000000000000000 softirq=21777/21777 fqs=587 
	(t=10503 jiffies g=27037 q=1321)
rcu: rcu_preempt kthread starved for 9327 jiffies! g27037 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:R  running task     stack:27464 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x29e/0x11b0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0x98/0x350 kernel/rcu/tree.c:2145
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 0 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 0 skipped: idling at default_idle+0xb/0x10 arch/x86/kernel/process.c:729
NMI backtrace for cpu 1
CPU: 1 PID: 8163 Comm: syz.7.951 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <IRQ>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x397/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
 rcu_dump_cpu_stacks+0x22f/0x380 kernel/rcu/tree_stall.h:349
 print_cpu_stall+0x31d/0x5f0 kernel/rcu/tree_stall.h:633
 check_cpu_stall kernel/rcu/tree_stall.h:727 [inline]
 rcu_pending kernel/rcu/tree.c:3936 [inline]
 rcu_sched_clock_irq+0x6d8/0x1110 kernel/rcu/tree.c:2619
 update_process_times+0x193/0x200 kernel/time/timer.c:1818
 tick_sched_handle kernel/time/tick-sched.c:254 [inline]
 tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473
 __run_hrtimer kernel/time/hrtimer.c:1690 [inline]
 __hrtimer_run_queues+0x4fe/0xc40 kernel/time/hrtimer.c:1754
 hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1816
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
 __sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:lock_release+0x584/0x870 kernel/locking/lockdep.c:5647
Code: 00 00 00 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 75 75 f7 44 24 50 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 2f 00 00 00 00 66 43 c7 44 2f 09 00 00 43 c6 44 2f 0b 00
RSP: 0018:ffffc90003906fa0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 2c7aebe1e80255c9 RCX: c55228d9beda1700
RDX: 0000000000000002 RSI: ffffffff8a0b28c0 RDI: ffffffff8a59a240
RBP: ffffc900039070c0 R08: dffffc0000000000 R09: fffffbfff1ad3196
R10: fffffbfff1ad3196 R11: 1ffffffff1ad3195 R12: ffff888027c36480
R13: dffffc0000000000 R14: ffff888027c36420 R15: 1ffff92000720e00
 __copy_from_user include/linux/uaccess.h:109 [inline]
 __kvm_read_guest_page+0x130/0x1c0 virt/kvm/kvm_main.c:2861
 kvm_fetch_guest_virt+0x11b/0x160 arch/x86/kvm/x86.c:6672
 __do_insn_fetch_bytes+0x298/0x680 arch/x86/kvm/emulate.c:961
 x86_decode_insn+0x316/0x47d0 arch/x86/kvm/emulate.c:5106
 x86_decode_emulated_instruction arch/x86/kvm/x86.c:8095 [inline]
 x86_emulate_instruction+0x233/0x2250 arch/x86/kvm/x86.c:8136
 __vmx_handle_exit arch/x86/kvm/vmx/vmx.c:6171 [inline]
 vmx_handle_exit+0xc77/0x18c0 arch/x86/kvm/vmx/vmx.c:6188
 vcpu_enter_guest+0x61a9/0x70e0 arch/x86/kvm/x86.c:10072
 vcpu_run arch/x86/kvm/x86.c:10162 [inline]
 kvm_arch_vcpu_ioctl_run+0xdea/0x1f40 arch/x86/kvm/x86.c:10399
 kvm_vcpu_ioctl+0x887/0xb80 virt/kvm/kvm_main.c:3894
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f72450aebe9
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:00007f7243316038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f72452e5fa0 RCX: 00007f72450aebe9
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000007
RBP: 00007f7245131e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f72452e6038 R14: 00007f72452e5fa0 R15: 00007ffff9238298
 </TASK>

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/02 12:29 linux-5.15.y 01879f56bdde 807a3b61 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in kvm_vcpu_ioctl
2025/06/30 09:35 linux-5.15.y 3dea0e7f549e fc9d8ee5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in kvm_vcpu_ioctl
2025/06/12 21:12 linux-5.15.y 1c700860e8bc 98683f8f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in kvm_vcpu_ioctl
2025/06/05 19:21 linux-5.15.y 1c700860e8bc 6b6b5f21 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in kvm_vcpu_ioctl
* Struck through repros no longer work on HEAD.