Hi Pat,

I found similar steps with ntfs-3g:

On the server side:
# Create volume and a file
dd if=/dev/zero of=ntfs-volume bs=1024 count=$((10*1024))
mkfs.ntfs -F ntfs-volume
mkdir /mnt/ntfs
ntfs-3g ntfs-volume /mnt/ntfs
echo foo > /mnt/ntfs/foo

# Remount
umount /mnt/ntfs
ntfs-3g ntfs-volume /mnt/ntfs

# Export
echo '/mnt/ntfs *(fsid=1)' > /etc/exports
exportfs -a


On the client side
mkdir /mnt/nfs
mount <SERVER>:/mnt/ntfs /mnt/nfs
find /mnt/nfs -exec cat {} \;  # <-- Server crashes

Cheers,
Jakob


On 11/11/14 16:36, Jakob Blomer wrote:
> Hi Pat,
> 
> thanks for the quick reply!  I just created a bugzilla account.
> 
> The best I can provide quickly uses the cvmfs file system, which is not
> in the standard repositories but it is a normal fuse module.
> 
> On the NFS server side:
>   o) Install cvmfs:
> yum install
> https://ecsft.cern.ch/dist/cvmfs/cvmfs-release/cvmfs-release-2-4.el6.noarch.rpm
> yum install cvmfs
> 
>   o) Configure and mount cvmfs
> echo 'CVMFS_HTTP_PROXY=DIRECT' > /etc/cvmfs/default.local
> echo 'CVMFS_NFS_SOURCE=yes' >> /etc/cvmfs/default.local
> mkdir /mnt/cvmfs
> mount -t cvmfs grid.cern.ch /mnt/cvmfs
> 
>   o) Export via NFS
> echo '/mnt/cvmfs *(ro,fsid=1)' > /etc/exports
> exportfs -ra
> 
> 
> On the NFS client side:
> mkdir /mnt/nfs
> mount <SERVER>:/mnt/cvmfs /mnt/nfs
> ls /mnt/nfs  # Server crashes
> 
> 
> Let me see if I can produce something similar with a fuse module that
> comes in the normal repository.
> 
> Cheers,
> Jakob
> 
> 
> On 11/11/14 15:23, Pat Riehecky wrote:
>> On 11/11/2014 07:50 AM, Jakob Blomer wrote:
>>> Dear Scientific Linux team,
>>>
>>> the latest kernel 2.6.32-504 crashes if a fuse file system is accessed
>>> from within the kernel space.  As discovered by Simon, this happens for
>>> instance when a fuse file system is re-exported via NFS.  When it
>>> happens, the stack trace starts with
>>>
>>> BUG: unable to handle kernel NULL pointer dereference at 0000000000000030
>>> IP: [<ffffffffa0202260>] fuse_dentry_revalidate+0xf0/0x400 [fuse]
>>>
>>>
>>> The behavior was not present with the previous kernel 2.6.32-431.29.2.
>>> Besides security patches, the latest kernel seems to also backport new
>>> fuse features which triggers the problem.  As a workaround, we managed
>>> to avoid the problem with a small kernel patch [1].
>>>
>>> Could you report the problem back to Redhat?  If necessary, I can
>>> provide detailed steps how to reproduce it.
>>>
>>> Cheers,
>>> Jakob
>>>
>>>
>>> [1]
>>> https://raw.githubusercontent.com/cvmfs/aufs2-standalone/aufs2.1-32-rhel6.6/rhel6.6-fuse.patch
>>>
>>
>> If we can get some more detailed replication steps it should help get
>> the issue clearly explained to upstream.
>>
>> Do you have a bugzilla account?
>>
>> Pat
>>