Re: Yet another kernel backtrace pointing at KVM

[Gleb Natapov <gleb@redhat.com>]

On Sun, Jun 28, 2009 at 10:20:50PM +0300, Ivelin Ivanov wrote:
> Hello KVM team,
> 
> I am using KVM for maintaining mixture of Windows and Linux VMs.
> The kernel version is 2.6.30.
> I am using the kernel's KVM module and qemu-kvm-0.86.
> 
The KVM in 2.6.30 does not handle task switch properly and it hits
WARN_ON() here. Current KVM tree should handle this better. What
operation system the guest that triggers this is running? It looks like
it configures some exception handler (may be #DF) to be a task gate.

> Jun 26 15:23:25 pc187 kernel: ------------[ cut here ]------------
> Jun 26 15:23:25 pc187 kernel: WARNING: at arch/x86/kvm/x86.c:204
> kvm_queue_exception_e+0x24/0x45 [kvm]()
> Jun 26 15:23:25 pc187 kernel: Hardware name: IBM System x3650 -[7979B4G]-
> Jun 26 15:23:25 pc187 kernel: Modules linked in: 8021q garp tun reiserfs
> st ide_gd_mod ide_cd_mod bridge stp kvm_intel kvm ipv6 af_packet cpufr
> eq_conservative cpufreq_userspace cpufreq_powersave acpi_cpufreq
> speedstep_lib loop dm_mod i5k_amb ibmpex i5000_edac ibmaem i2c_i801
> iTCO_wdt i
> TCO_vendor_support rtc_cmos bnx2 sr_mod rtc_core ipmi_msghandler ses
> edac_core rtc_lib button pcspkr i2c_core cdrom serio_raw enclosure shpchp
> pci_hotplug joydev sg usbhid hid uhci_hcd ehci_hcd usbcore sd_mod
> crc_t10dif edd ext3 mbcache jbd fan ide_pci_generic ide_core ata_generic
> ata_
> piix libata thermal processor thermal_sys hwmon aacraid scsi_mod
> Jun 26 15:23:25 pc187 kernel: Pid: 3452, comm: qemu-system-x86 Tainted:
> G        W  2.6.30-9-pae #1
> Jun 26 15:23:25 pc187 kernel: Call Trace:
> Jun 26 15:23:25 pc187 kernel:  [<c012eda8>] warn_slowpath_common+0x60/0x90
> Jun 26 15:23:25 pc187 kernel:  [<c012ede5>] warn_slowpath_null+0xd/0x10
> Jun 26 15:23:25 pc187 kernel:  [<f7fea423>]
> kvm_queue_exception_e+0x24/0x45 [kvm]
> Jun 26 15:23:25 pc187 kernel:  [<f7feb509>] kvm_task_switch+0xfb/0xada [kvm]
> Jun 26 15:23:25 pc187 kernel:  [<f7fec1e5>] ?
> kvm_inject_page_fault+0x5a/0x5f [kvm]
> Jun 26 15:23:25 pc187 kernel:  [<f7ff041e>] ?
> kvm_mmu_page_fault+0x16/0x75 [kvm]
> Jun 26 15:23:25 pc187 kernel:  [<f805dea3>] handle_task_switch+0x6d/0x96
> [kvm_intel]
> Jun 26 15:23:25 pc187 kernel:  [<f805e3fd>] kvm_handle_exit+0x1c3/0x1e0
> [kvm_intel]
> Jun 26 15:23:25 pc187 kernel:  [<f805d235>] ?
> vmx_queue_exception+0xf9/0xfe [kvm_intel]
> Jun 26 15:23:25 pc187 kernel:  [<f7feb11a>]
> kvm_arch_vcpu_ioctl_run+0x89d/0xab6 [kvm]
> Jun 26 15:23:25 pc187 kernel:  [<c01a7cfd>] ? do_sync_readv_writev+0xa1/0xdf
> Jun 26 15:23:25 pc187 kernel:  [<f7fe34ef>] kvm_vcpu_ioctl+0xec/0x602 [kvm]
> Jun 26 15:23:25 pc187 kernel:  [<c03441e2>] ? _spin_unlock+0xf/0x23
> Jun 26 15:23:25 pc187 kernel:  [<c014de53>] ?
> generic_smp_call_function_single_interrupt+0x6c/0x9e
> Jun 26 15:23:25 pc187 kernel:  [<c01336e0>] ? irq_exit+0x61/0x63
> Jun 26 15:23:25 pc187 kernel:  [<c0110005>] ?
> smp_call_function_single_interrupt+0x2d/0x2f
> Jun 26 15:23:25 pc187 kernel:  [<c010327a>] ?
> call_function_single_interrupt+0x2a/0x30
> Jun 26 15:23:25 pc187 kernel:  [<f7fe3403>] ? kvm_vcpu_ioctl+0x0/0x602 [kvm]
> Jun 26 15:23:25 pc187 kernel:  [<c01b2fe7>] vfs_ioctl+0x22/0x69
> Jun 26 15:23:25 pc187 kernel:  [<c01b3467>] do_vfs_ioctl+0x439/0x472
> Jun 26 15:23:25 pc187 kernel:  [<c0110005>] ?
> smp_call_function_single_interrupt+0x2d/0x2f
> Jun 26 15:23:25 pc187 kernel:  [<c010327a>] ?
> call_function_single_interrupt+0x2a/0x30
> Jun 26 15:23:25 pc187 kernel:  [<c01a8e52>] ? fget_light+0x8a/0xb1
> Jun 26 15:23:25 pc187 kernel:  [<c01b34e0>] sys_ioctl+0x40/0x5a
> Jun 26 15:23:25 pc187 kernel:  [<c0102b0c>] sysenter_do_call+0x12/0x28
> Jun 26 15:23:25 pc187 kernel: ---[ end trace 9cc5a56b9c7eda33 ]---
> 
> Here is some more info:
> # uname -a
> Linux pc187 2.6.30-9-pae #1 SMP PREEMPT Wed Jun 17 15:29:59 EEST 2009
> i686 i686 i386 GNU/Linux
> # qemu-system-x86_64  --version
> QEMU PC emulator version 0.10.50 (qemu-kvm-devel-86), Copyright (c)
> 2003-2008 Fabrice Bellard
> # modinfo /lib/modules/2.6.30-9-pae/kernel/arch/x86/kvm/kvm.ko
> filename:       /lib/modules/2.6.30-9-pae/kernel/arch/x86/kvm/kvm.ko
> license:        GPL
> author:         Qumranet
> srcversion:     934CD9DB264501B0431438A
> depends:
> vermagic:       2.6.30-9-pae SMP preempt mod_unload modversions CORE2
> parm:           oos_shadow:bool
> parm:           msi2intx:bool
> 
> Hope to hear from you soon.
> Best regards,
> 
> Ivelin Ivanov
> 
> P.S. No mini-dumps were found in the WinXP VM
> 
> 
> 
> 
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--
			Gleb.