Re: NFS oops in 2.6.26rc4

[Dave Jones <davej@redhat.com>]

On Fri, May 30, 2008 at 01:59:12PM -0400, Chuck Lever wrote:

 > > When trying to mount an nfs export, I got this oops..
 > >
 > > BUG: unable to handle kernel paging request at f4569000
 > > IP: [<f8daac01>] :sunrpc:xdr_encode_opaque_fixed+0x2d/0x69
 > > *pde = 34c23163 *pte = 34569160
 > > Oops: 0000 [#1] SMP DEBUG_PAGEALLOC
 > > Modules linked in: nfs nfsd lockd nfs_acl auth_rpcgss exportfs sunrpc ext2 sg button via_rhine via_ircc pcspkr r8169 mii pata_sil680 irda crc_ccitt i2c_viapro i2c_core dm_snapshot dm_zero dm_mirror dm_log dm_mod pata_via ata_generic pata_acpi libata sd_mod scsi_mod ext3 jbd mbcache uhci_hcd ohci_hcd ehci_hcd [last unloaded: scsi_wait_scan]
 > > ...
 > > Code: e5 57 56 89 d6 53 83 ec 04 85 c9 89 45 f0 89 c8 74 4c 8d 59 03 c1 eb 02 8d 14 9d 00 00 00 00 29 ca 85 f6 74 11 c1 e9 02 8b 7d f0 <f3> a5 89 c1 83 e1 03 74 02 f3 a4 85 d2 74 1b 8b 7d f0 89 d1 c1
 > > EIP: [<f8daac01>] xdr_encode_opaque_fixed+0x2d/0x69 [sunrpc] SS:ESP 0068:f4566a68
 > > ---[ end trace a8a691a45122c25a ]---
 > > mount.nfs used greatest stack depth: 812 bytes left
 > 
 > The last line suggests you are trying this with 4KB kernel stacks.  I
 > have patches queued for .27 that provide some stack relief in this
 > code path.  If you hit this often, you might want to try with 8KB
 > stacks to see if that helps.

Yes, Fedora kernels have been using 4K stacks for some time.
>From the trace though, it doesn't look like we actually ran out of
stack space ? 

 > In the meantime, the traceback is a little funky, so I can't see
 > directly what the root cause is.  Can you provide the full command
 > line of the mount command that caused this?

mount point in the fstab is ..

gelk:/mnt/data      /mnt/nfs/gelk       nfs     nfsvers=3,tcp        0 0

 >  What "brand" of server were you trying to mount?

It's just another linux box. A no-name core2 duo, running 2.6.25.

 > How often can you reproduce this?

Seems to do it every time I ask it to.

	Dave

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