Re: I/O errors after migration - why?

[Tomasz Chmielewski <mangoo@wpkg.org>]

Tomasz Chmielewski schrieb:
> Tomasz Chmielewski schrieb:
>> I'm trying to perform live migration by following the instructions on 
>> http://www.linux-kvm.org/page/Migration.
>> Unfortunately, it doesn't work very well - guest is migrated, but 
>> looses access to its disk.
>>
>> On the destination host, I'm starting the guest with exactly the same 
>> options as on the source host, with "-incoming tcp:0:4444".
>> On the source host, I start the migration with "migrate -d tcp:B:4444".
>>
>> Both hosts use the same iSCSI device and can access it.
>>
>> Looks like the destination host can't really access the iSCSI device 
>> after all? No - after I reboot the guest (echo b > 
>> /proc/sysrq-trigger), it boots just fine from its disk. Also lsof on 
>> the host shows that the kvm process accesses the correct /dev/sdX device.
> 
> Similar symptoms with virtio_blk (i.e., when guest is booted off a live 
> CD and tries to access the disk after migration).
> 
> The only difference between SCSI and virtio_blk is that SCSI signals 
> errors and aborts, and virtio_blk waits forever and doesn't give a clue.

I get this kernel BUG when I remove virtio_blk after migration
(virtio block device was not mounted or used during migration).


------------[ cut here ]------------
kernel BUG at drivers/virtio/virtio.c:140!
invalid opcode: 0000 [#1] SMP
Modules linked in: virtio_blk(-) ipv6 video output ac battery button e1000 ppdev parport_pc i2c_piix4 i2c_core btrfs libcrc32c raid10 raid456 async_xor async_memcpy async_tx xor raid1 raid0 dm_snapshot dm_mirror dm_log dm_mod sbp2 ohci1394 ieee1394 sl811_hcd ohci_hcd uhci_hcd usb_storage ehci_hcd osst sym53c8xx atp870u hptiop ses enclosure aic79xx aic7xxx aic94xx ppa raid_class sym53c500_cs qlogic_cs qlogicfas408 aacraid imm parport mvsas libsas 3w_xxxx initio gdth arcmsr stex tmscsim dc395x iscsi_tcp 3w_9xxx a100u2w BusLogic sr_mod cdrom libsrp libiscsi st ch scsi_transport_srp scsi_transport_spi qla4xxx scsi_transport_iscsi qla2xxx lpfc scsi_transport_fc scsi_transport_sas qla1280 megaraid_sas megaraid ata_piix pdc_adma ahci sata_vsc sata_via sata_uli sata_sx4 sata_svw sata_sis sata_sil 
 sata_sil24 sata_qstor sata_promise sata_nv sata_mv sata_inic162x scsi_wait_scan pata_via pata_triflex pata_sl82c105 pata_sis pata_sil680 pata_serverworks pata_sch pata_pdc202xx_old pata_pdc2
027x pata_pcmcia pata_opti pata_optidma pata_oldpiix pata_ns87415 pata_ns87410 pata_ninja32 pata_netcell pata_mpiix pata_marvell pata_jmicron pata_it821x pata_it8213 pata_hpt3x3 pata_hpt3x2n pata_hpt37x pata_hpt366 pata_efar pata_cypress pata_cs5530 pata_cs5520 pata_cmd64x pata_cmd640 pata_atiixp pata_artop pata_amd pata_ali pata_acpi libata

Pid: 6496, comm: rmmod Not tainted (2.6.27.19-std117 #1)
EIP: 0060:[<c0779f51>] EFLAGS: 00010286 CPU: 0
EIP is at virtio_dev_remove+0x21/0x36
EAX: 000000ff EBX: d8a15c00 ECX: c132653c EDX: 0000c092
ESI: d9dcfd44 EDI: d9dcfd44 EBP: d757cef8 ESP: d757cef4
 DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
Process rmmod (pid: 6496, ti=d757c000 task=d63998e0 task.ti=d757c000)
Stack: d8a15c04 d757cf08 c07068f5 d8a15c04 d8a15cc0 d757cf1c c0706c7b d9dcfd44
       00000000 c09c2cf0 d757cf30 c0705f64 00000000 d9dcfd44 00000880 d757cf40
       c0706ce9 d9dcfe00 00000000 d757cf48 c077a00a d757cf50 d9dcf674 d757cfb0
Call Trace:
 [<c07068f5>] ? __device_release_driver+0x5b/0x78
 [<c0706c7b>] ? driver_detach+0x72/0x97
 [<c0705f64>] ? bus_remove_driver+0x63/0x7f
 [<c0706ce9>] ? driver_unregister+0x2a/0x2e
 [<c077a00a>] ? unregister_virtio_driver+0x8/0xa
 [<d9dcf674>] ? cleanup_module+0x1c/0x1e [virtio_blk]
 [<c044807a>] ? sys_delete_module+0x182/0x1d0
 [<c043bc74>] ? up_read+0x8/0xa
 [<c0811e64>] ? do_page_fault+0x36e/0x672
 [<c0403f02>] ? syscall_call+0x7/0xb
 =======================
Code: 94 c0 51 e8 0b 80 f2 ff c9 c3 55 89 e5 53 8d 58 fc 8b 93 d4 00 00 00 89 d8 ff 52 40 8b 93 40 01 00 00 89 d8 ff 52 08 84 c0 74 04 <0f> 0b eb fe 89 d8 ba 01 00 00 00 e8 f2 fe ff ff 31 c0 5b 5d c3
EIP: [<c0779f51>] virtio_dev_remove+0x21/0x36 SS:ESP 0068:d757cef4
---[ end trace 1d9e100e68f9d27e ]---



-- 
Tomasz Chmielewski
http://wpkg.org