Re: [Xen-devel] ext4_mb_generate_buddy remounting read-only on domU

[Konrad Rzeszutek Wilk <konrad@xxxxxxxxxx>]

On Wed, Nov 30, 2011 at 11:04:44AM +0100, Sergi Seira wrote:
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> Hi,
> 
> has anyone had ext4 filesystem remounting hours after a live-migration?
> 
> We've been having those 'read only remounts' always hours after a 
> live-migration.
> The more load a domU has the faster we get 'read only remount'.
> We are suspecting something is getting corrupted after a live migration, and 
> under load an error bumps:
> 
>  kernel: [3424760.190005] EXT4-fs error (device xvda3): 
> ext4_mb_generate_buddy: EXT4-fs: group 55: 6102 blocks in bitmap, 6101 in gd
>  kernel: [3424760.190059] Aborting journal on device xvda3-8.
>  kernel: [3424760.191197] EXT4-fs (xvda3): Remounting filesystem read-only
>  kernel: [3424760.204396] EXT4-fs (xvda3): delayed block allocation failed 
> for inode 374665 at logical offset 318 with max blocks 1 with error -30
>  kernel: [3424760.204447] This should not happen!!  Data will be lost
>  kernel: [3424760.204483] EXT4-fs (xvda3): ext4_da_writepages: jbd2_start: 
> 1015 pages, ino 374665; err -30
> 
> We have to fsck the volume from dom0 before re-creating domU.
> 
> Our system runs on :
> 
>  dom0 debian6 2.6.32-5-xen-amd64

This looks familiar,
http://xen.1045712.n5.nabble.com/ext4-BUG-in-dom0-Kernel-2-6-32-36-td4773487.html

Ah no. There was some fix to blktap for this I think. What exactly is
the drivery you are using to drive the root/home/swap of the guest? Is
it blkback or blktap?


>  xen-hypervisor 4.0.1-2
> 
> DomU are:
> 
>  domU paravirtual debian6 2.6.32-5-xen-amd64
>  3 iscsi volumes act as vxda's, swap, root and home (400G)
>  7 vcpus
>  8 GB RAM
> 
> Regards,
> Sergi
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