[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Re: NFS kernel oops with Thecus DMA patch

On Fri, Sep 25, 2009 at 06:06:35PM +0100, Martin Michlmayr wrote:
> * Steve Langasek <vorlon@debian.org> [2009-09-22 23:28]:
> > After building myself a 2.6.30 kernel with the iop dma patches for my Thecus,
> > I started seeing reproducible kernel oopses on large NFS transfers, such as
> > the one included below.  After some prodding at the source for other uses of
> > down_read(), I concluded that we're not supposed to call
> > down_read(&current->mm->mmap_sem) if in_atomic() is true.  Updating the dma1
> > patch from http://people.debian.org/~tbm/dma/dma-patch to the attached
> > appears to have fixed the problem for me, giving me a stable DMA-enabled
> > squeeze kernel.

> Thanks a lot for investigating and fixing this issue!  I'm building an
> updated kernel for lenny with this fix now.

Sorry, it turns out this didn't fix the problem after all. :/  Putting NFS
load on the system caused the panic to reappear again, and even downgrading
to the 2.6.26 dma kernel doesn't fix it; so it seems it was just coincidence
that it first appeared after I upgraded, and this patch is a wash.

Vince Sanders suggests this is a misuse-of-the-DMA-engine problem generally,
perhaps related to alignment issues.

Steve Langasek                   Give me a lever long enough and a Free OS
Debian Developer                   to set it on, and I can move the world.
Ubuntu Developer                                    http://www.debian.org/
slangasek@ubuntu.com                                     vorlon@debian.org

Attachment: signature.asc
Description: Digital signature

Reply to: