Re: linux-next regression: IO errors in with ext4 and xen-blkfront

[Jeremy Fitzhardinge <jeremy@goop.org>]

 On 10/20/2010 05:04 PM, Jeremy Fitzhardinge wrote:
>  Hi,
>
> When doing some regression testing with Xen on linux-next, I'm finding
> that my domains are failing to get through the boot sequence due to IO
> errors:
>
> Remounting root filesystem in read-write mode:  EXT4-fs (dm-0): re-mounted. Opts: (null)
> [  OK  ]
> Mounting local filesystems:  EXT3-fs: barriers not enabled
> kjournald starting.  Commit interval 5 seconds
> EXT3-fs (xvda1): using internal journal
> EXT3-fs (xvda1): mounted filesystem with writeback data mode
> SELinux: initialized (dev xvda1, type ext3), uses xattr
> SELinux: initialized (dev xenfs, type xenfs), uses genfs_contexts
> [  OK  ]
> Enabling local filesystem quotas:  [  OK  ]
> Enabling /etc/fstab swaps:  Adding 917500k swap on /dev/mapper/vg_f1364-lv_swap.  Priority:-1 extents:1 across:917500k 
> [  OK  ]
> SELinux: initialized (dev binfmt_misc, type binfmt_misc), uses genfs_contexts
> Entering non-interactive startup
> Starting monitoring for VG vg_f1364:   2 logical volume(s) in volume group "vg_f1364" monitored
> [  OK  ]
> ip6tables: Applying firewall rules: [  OK  ]
> iptables: Applying firewall rules: [  OK  ]
> Bringing up loopback interface:  [  OK  ]
> Bringing up interface eth0:  
> Determining IP information for eth0... done.
> [  OK  ]
> Starting auditd: [  OK  ]
> end_request: I/O error, dev xvda, sector 0
> end_request: I/O error, dev xvda, sector 0
> end_request: I/O error, dev xvda, sector 9675936
> Aborting journal on device dm-0-8.
> Starting portreserve: EXT4-fs error (device dm-0): ext4_journal_start_sb:259: Detected aborted journal
> EXT4-fs (dm-0): Remounting filesystem read-only
> [  OK  ]
> Starting system logger: EXT4-fs (dm-0): error count: 4
> EXT4-fs (dm-0): initial error at 1286479997: ext4_journal_start_sb:251
> EXT4-fs (dm-0): last error at 1287618175: ext4_journal_start_sb:259
>
>
> I haven't tried to bisect this yet (which will be awkward because
> linux-next had also introduced various Xen bootcrashing bugs), but I
> wonder if you have any thoughts about what may be happening here.  I
> guess an obvious candidate is the barrier changes in the storage
> subsystem, but I still get the same errors if I mount root with barrier=0.

Hm.  I get the same errors, but the system boots to login prompt rather
than hanging at that point above, and seems generally happy.  So perhaps
barriers are the key.

> Current linux-2.6 mainline is fine, so the problem is in some of the
> patches targeted at the next merge window.
>


Thanks,
    J