SRU request for LP#58170
 

https://bugs.launchpad.net/ubuntu/+source/linux-source-2.6.15/+bug/58170

SRU justification:

Impact: Kernel BUG in lib/radix-tree.c:372.

There is no serialisation between NFS asynchronous writebacks
and truncation at the page level due to the fact that nfs_sync_inode()
cannot lock the pages that it is about to write out.

This means that it is possible to be flushing out data (and calling something
like set_page_writeback()) while the page cache is busy evicting the page.

Fix: Backport of upstream cherry pick cd52ed35535ef443f08bf5cd3331d350272885b8

Testcases:

1. Dapper Kernel always freezes when it mounts nfsv4 filesystems
and
2. Virtual vmware machines are on a nfs mounted filesystem. One vmware
machine goes unuseable and comsumes all the CPU time. A kill -KILL pid
doesn't wipe out the vmware process. A ls -lh on the nfs mount hangs.
and
3. Create file i/o's in a virtual host, for example copy folder to other
and kernel BUG in lib/radix-tree.c occurs.

Patch verified on a 2.6.15 AMD64 server kernel image
https://bugs.launchpad.net/ubuntu/+source/linux-source-2.6.15/+bug/58170/comments/19

Patch Attached.


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SRU request for LP#58170
 

Colin Ian King wrote:
> https://bugs.launchpad.net/ubuntu/+source/linux-source-2.6.15/+bug/58170
>
> SRU justification:
>
> Impact: Kernel BUG in lib/radix-tree.c:372.
>
> There is no serialisation between NFS asynchronous writebacks
> and truncation at the page level due to the fact that nfs_sync_inode()
> cannot lock the pages that it is about to write out.
>
> This means that it is possible to be flushing out data (and calling something
> like set_page_writeback()) while the page cache is busy evicting the page.
>
> Fix: Backport of upstream cherry pick cd52ed35535ef443f08bf5cd3331d350272885b8
>
> Testcases:
>
> 1. Dapper Kernel always freezes when it mounts nfsv4 filesystems
> and
> 2. Virtual vmware machines are on a nfs mounted filesystem. One vmware
> machine goes unuseable and comsumes all the CPU time. A kill -KILL pid
> doesn't wipe out the vmware process. A ls -lh on the nfs mount hangs.
> and
> 3. Create file i/o's in a virtual host, for example copy folder to other
> and kernel BUG in lib/radix-tree.c occurs.
>
> Patch verified on a 2.6.15 AMD64 server kernel image
> https://bugs.launchpad.net/ubuntu/+source/linux-source-2.6.15/+bug/58170/comments/19
>
> Patch Attached.
>
>
>

ACK - You need to subscribe ubuntu-sru and nominate for Dapper release
before the archive admins will notice that it is an SRU.

rtg
--
Tim Gardner tim.gardner@ubuntu.com

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