blktap-dkms links to missing symbols in kernel 3.5

[Mike McClurg]

The blktap-dkms kernel module links to two symbols which were removed from the 3.5 kernel tree. dmesg shows the following:

$ dmesg | grep blktap
[ 18.067395] blktap: Unknown symbol do_munmap (err 0)
[ 18.067478] blktap: Unknown symbol do_mmap_pgoff (err 0)

It seems that the new functions are called vm_munmap and vm_mmap_pgoff.

This bug prevents the blktap kernel module from loading, and in turn prevents xcp-xapi from starting at all.

[Mike McClurg (mike-mcclurg)]

Marking confirmed.

[Mike McClurg (mike-mcclurg)]

Unverified fix:

https://github.com/mcclurmc/blktap-dkms/commit/d33302b91d42e605f64e561488811064028cc4d1

This fix "works" in that it compiles and the resulting module loads cleanly ;) Need to do some testing tomorrow.

[Tamas Lengyel (tamas-k-lengyel)]

The fix seems to be running fine for me. No issues so far with several qcow2 xen vm's.

[Mike McClurg (mike-mcclurg)]

I haven't uploaded this fix yet ;) Anyway, blktap doesn't speak qcow, so I don't think that the issue would manifest itself for you. The issue is that the blktap kernel module doesn't even build on the 3.5 kernel without the patch that I referred to in #2.

[Mike McClurg (mike-mcclurg)]

I've resolved this issue in upstream blktap-dkms, and pushed the updated deb package to the xcp-unstable PPA [1]. The fixed version is blktap-dkms-2.0.93-1ubuntu1~quantal. The upstream source repo is here [2] if anyone wants to take a look.

I'll see if I an initiate a requestsync directly from the PPA. This fix hasn't been able to go into Debian yet, because they haven't put kernel 3.5 into Sid yet (I think it just hit experimental, so I'll see about getting this package into experimental).

[1] https://launchpad.net/~ubuntu-xen-org/+archive/xcp-unstable/
[2] https://github.com/mcclurmc/blktap-dkms/

[Launchpad Janitor (janitor)]

This bug was fixed in the package blktap-dkms - 2.0.93-0ubuntu1

---------------
blktap-dkms (2.0.93-0ubuntu1) quantal; urgency=low

  * New upstream release which fixes compatiblity with linux 3.5
    kernel (LP: #1028135).
 -- James Page <email address hidden> Fri, 07 Sep 2012 17:28:22 +0100

[Mike McClurg (mike-mcclurg)]

Thanks James!