Re: INFO: rcu detected stall in kvm_arch_vcpu_ioctl_run

[Dmitry Vyukov <dvyukov@google.com>]

On Tue, Sep 11, 2018 at 8:12 AM, syzbot
<syzbot+b3fdc9590894087f1188@syzkaller.appspotmail.com> wrote:
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    3d0e7a9e00fd Merge tag 'md/4.19-rc2' of git://git.kernel.o..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=12820cd1400000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=8f59875069d721b6
> dashboard link: https://syzkaller.appspot.com/bug?extid=b3fdc9590894087f1188
> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=16940056400000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+b3fdc9590894087f1188@syzkaller.appspotmail.com

#syz dup: INFO: rcu detected stall in kvm_vcpu_ioctl

> 8021q: adding VLAN 0 to HW filter on device team0
> 8021q: adding VLAN 0 to HW filter on device team0
> 8021q: adding VLAN 0 to HW filter on device team0
> hrtimer: interrupt took 32920 ns
> L1TF CPU bug present and SMT on, data leak possible. See CVE-2018-3646 and
> https://www.kernel.org/doc/html/latest/admin-guide/l1tf.html for details.
> rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
> rcu:    (detected by 1, t=10502 jiffies, g=7509, q=466)
> rcu: All QSes seen, last rcu_preempt kthread activity 10502
> (4295044073-4295033571), jiffies_till_next_fqs=1, root ->qsmask 0x0
> syz-executor7   R  running task    23424  7586   5576 0x00000000
> Call Trace:
>  <IRQ>
>  sched_show_task.cold.83+0x2b6/0x30a kernel/sched/core.c:5296
>  print_other_cpu_stall.cold.79+0xa83/0xba5 kernel/rcu/tree.c:1430
>  check_cpu_stall kernel/rcu/tree.c:1557 [inline]
>  __rcu_pending kernel/rcu/tree.c:3276 [inline]
>  rcu_pending kernel/rcu/tree.c:3319 [inline]
>  rcu_check_callbacks+0xafc/0x1990 kernel/rcu/tree.c:2665
>  update_process_times+0x2d/0x70 kernel/time/timer.c:1636
>  tick_sched_handle+0x9f/0x180 kernel/time/tick-sched.c:164
>  tick_sched_timer+0x45/0x130 kernel/time/tick-sched.c:1274
>  __run_hrtimer kernel/time/hrtimer.c:1398 [inline]
>  __hrtimer_run_queues+0x41c/0x10d0 kernel/time/hrtimer.c:1460
>  hrtimer_interrupt+0x313/0x780 kernel/time/hrtimer.c:1518
>  local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1029 [inline]
>  smp_apic_timer_interrupt+0x1a1/0x760 arch/x86/kernel/apic/apic.c:1054
>  apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:864
>  </IRQ>
> RIP: 0010:arch_local_irq_enable arch/x86/include/asm/paravirt.h:798 [inline]
> RIP: 0010:vcpu_enter_guest+0x12ad/0x62e0 arch/x86/kvm/x86.c:7610
> Code: 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 b7 4a 00 00 48 83 3d bd 8c 43 08
> 00 0f 84 b1 3d 00 00 e8 3a 32 70 00 fb 66 0f 1f 44 00 00 <bf> 01 00 00 00 e8
> 09 cf 46 00 31 ff 65 44 8b 25 af 50 f3 7e 44 89
> RSP: 0018:ffff8801b116f4f0 EFLAGS: 00000293 ORIG_RAX: ffffffffffffff13
> RAX: ffff8801cd182680 RBX: ffff8801d97f8080 RCX: 1ffff10039a305e4
> RDX: 0000000000000000 RSI: ffffffff810e9d06 RDI: ffffffff895229b8
> RBP: ffff8801b116f840 R08: ffff8801cd182f20 R09: 0000000000000006
> R10: 0000000000000000 R11: ffff8801cd182680 R12: ffff8801cd182680
> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
>  vcpu_run arch/x86/kvm/x86.c:7693 [inline]
>  kvm_arch_vcpu_ioctl_run+0x375/0x16e0 arch/x86/kvm/x86.c:7870
>  kvm_vcpu_ioctl+0x72b/0x1150 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2590
>  vfs_ioctl fs/ioctl.c:46 [inline]
>  file_ioctl fs/ioctl.c:501 [inline]
>  do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685
>  ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702
>  __do_sys_ioctl fs/ioctl.c:709 [inline]
>  __se_sys_ioctl fs/ioctl.c:707 [inline]
>  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707
>  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x457099
> Code: fd b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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
> 0f 83 cb b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007ffdfe480958 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> RAX: ffffffffffffffda RBX: 0000000001598914 RCX: 0000000000457099
> RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000006
> RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
> R13: 00000000004cf730 R14: 00000000004c59b9 R15: 0000000000000000
> rcu: rcu_preempt kthread starved for 10502 jiffies! g7509 f0x2
> RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
> rcu: RCU grace-period kthread stack dump:
> rcu_preempt     R  running task    22872    10      2 0x80000000
> Call Trace:
>  context_switch kernel/sched/core.c:2825 [inline]
>  __schedule+0x86c/0x1ed0 kernel/sched/core.c:3473
>  schedule+0xfe/0x460 kernel/sched/core.c:3517
>  schedule_timeout+0x140/0x260 kernel/time/timer.c:1804
>  rcu_gp_kthread+0x9d9/0x2310 kernel/rcu/tree.c:2194
>  kthread+0x35a/0x420 kernel/kthread.c:246
>  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413
>
>
> ---
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