[linux-lvm] Re: Kernel oops on while resizing logical volume (data loss)

Dave Kleikamp shaggy at austin.ibm.com
Mon Oct 23 17:13:42 UTC 2006

On Mon, 2006-10-23 at 18:11 +0200, Allard Hoeve wrote:
> Dear LVM maintainers,
> (JFS maintainer CC'ed because of crash on LVM + JFS)
> Today I encountered a kernel oops while resizing one of our logical volumes. 
> Others at the office have encountered this oops before, but until now I haven't 
> had the chance to get to the oops message itself.
> A short description of the machine:
> * The machine is a Dell PowerEdge 2850 (megaraid_mbox 4e/Di SCSI)
> * There are 6 disks in a RAID5 setup (one large logical disk)
> * The machine had medium load overall
> * The machine had low load on the partition to be resized
> Output of lsmod and lspci -vv attached.
> Description of the setup:
> * The machine was running a vanilla Linux
> * The machine was running Debian Sarge (lvm2 2.01.04-5)
> * 80% of the RAID5 array covered by LVM2
> * One volume group
> * Five logical volumes
> About the crash:
> * I was using lvextend -L +100G /dev/srv/home
> * Oops happend during resize
> * The partition in question had a JFS filesystem
> * Resizing the largest logical volume
> * Resizing from 150 to 250 GB
> * Partition was mounted read/write (online)
> * Two other resizes had finished succesfully happened before
>    the kernel oops occurred

It looks like lbmRead() (jfs) called submit_bio() where bio->bi_bdev is
NULL.  I don't know how this can be happening, and it doesn't look like
anything I've seen before.  I didn't see any lv's that appear to be an
external journal, so I'm assuming the partition has an internal journal.

> After a reboot:
> * Second attempt at lvresize succeeded after reboot
> * mount -o remount,resize of filesystem succeeded
> It seems like this bug is only triggered on consecutive resize attempts, but I 
> cannot confirm this.

I'll look a bit closer to see if I can find any way multiple resizes
might lead to a null bdev somewhere.

> Output of vgs and lvs attached (unfortunately only of the new situation)
> The oops itself:
> See attached file. Please note the NULL pointer and memory allocation function 
> references.
> I hope this information is complete. If you require any more information about 
> this, please don't hesitate to contact me. If you do, please CC me, I'm not on 
> any of the LVS lists.
> Thanks for your time,
> Sincerely,
> Allard Hoeve
David Kleikamp
IBM Linux Technology Center

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