Re: KVM host kernel hang

[Avi Kivity <avi@redhat.com>]

Alexander Graf wrote:
> Hi,
>
> while trying to run a current openSUSE in VMWare ESX in KVM (using NPT),
> some KVM code seems to be stuck in an endless loop. The qemu process
> hangs, I can't attach gdb to it and the kernel module seems to be
> hanging in a place where I don't see any looping code. One CPU is
> definitely stuck in sys at 100% though.
>
> This is running git as of yesterday with some minor ESX modifications
> that should not touch any of these parts (userspace and MSRs).
>
> Maybe one of you guys has a clue what's going on here. You'll find a
> snippet of a t-sysrq trace with all qemu relevant parts below. The
> registers (incl. IP) of these don't change over time.
>
> Alex
>
> qemu-system-x D ffff810001025280     0 27900   9501
>  ffff8101000e5c58 0000000000000082 0000000000000000 ffff8101000e5c1c
>  ffff81011446e728 ffffffff807e6280 ffffffff807e6280 ffff8100388ca680
>  ffffffff80601890 ffff8100388ca9c0 0000000000200200 ffff8100388ca9c0
> Call Trace:
>  [<ffffffff804485ec>] __mutex_lock_slowpath+0x72/0xa9
>  [<ffffffff8044847a>] mutex_lock+0x1e/0x22
>  [<ffffffff88d7f630>] :kvm:kvm_arch_vm_ioctl+0x30e/0x5ae
>  [<ffffffff88d7c78e>] :kvm:kvm_vm_ioctl+0x744/0x777
>  [<ffffffff802acada>] vfs_ioctl+0x2a/0x78
>  [<ffffffff802acd6f>] do_vfs_ioctl+0x247/0x261
>  [<ffffffff802acdde>] sys_ioctl+0x55/0x77
>  [<ffffffff8020bffa>] system_call_after_swapgs+0x8a/0x8f
>  [<00007f2f3b15eb67>]
>
>   

Waiting for kvm->lock, so can't kill or strace.

> qemu-system-x R  running task        0 27908   9501
>  0000000000000000 ffffffff88d7d3ad 0000000000000390 ffff810100120040
>  ffff810116491000 00000000fee00390 0000000000000000 0000000000000000
>  ffff81011b361d08 ffffffff88d7f1fb 0000000000000000 0000000100000000
> Call Trace:
> Inexact backtrace:
>
>  [<ffffffff88d7d3ad>] :kvm:kvm_get_cs_db_l_bits+0x27/0x3e
>  [<ffffffff88d7f1fb>] :kvm:emulate_instruction+0x199/0x266
>  [<ffffffff88d86700>] :kvm:kvm_mmu_page_fault+0x49/0x86
>  [<ffffffff88a3ebe8>] :kvm_amd:pf_interception+0xa8/0xb1
>  [<ffffffff88a3e1b4>] :kvm_amd:handle_exit+0x218/0x221
>  [<ffffffff88d810f6>] :kvm:kvm_arch_vcpu_ioctl_run+0x600/0x81a
>  [<ffffffff88d7a4f0>] :kvm:kvm_vcpu_ioctl+0xf6/0x485
>  [<ffffffff802acada>] vfs_ioctl+0x2a/0x78
>  [<ffffffff802acd6f>] do_vfs_ioctl+0x247/0x261
>  [<ffffffff802a13a3>] fget_light+0x1/0x83
>  [<ffffffff802acdde>] sys_ioctl+0x55/0x77
>  [<ffffffff802a0b48>] sys_writev+0x60/0x94
>  [<ffffffff8020bffa>] system_call_after_swapgs+0x8a/0x8f
>   

But the mutex is not taken here.  Looks like we lost it, maybe 
CONFIG_LOCKDEP can find out where.

-- 
error compiling committee.c: too many arguments to function