Re: [Xen-devel] xend segfaults when starting

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Wed, 11 Aug 2010, Ian Campbell wrote:
> On Wed, 2010-08-04 at 15:55 +0100, Stefano Stabellini wrote:
> > > > On Wed, 2010-08-04 at 14:12 +0100, Christoph Egger wrote:
> > > > > Hi!
> > > > >
> > > > > xend causes python to segfault on startup.
> > > > > The changeset in error is: 21904:6a0dd2c29999
> > > >
> 
> > It doesn't, in fact:
> > 
> > changeset:   21907:6a0dd2c29999
> > parent:      21904:9f49667fec71
> > user:        Ian Campbell <ian.campbell@xxxxxxxxxx>
> > date:        Fri Jul 30 16:20:48 2010 +0100
> > summary:     libxc: free thread specific hypercall buffer on
> > xc_interface_close
> > 
> > I am going to revert this and leave it to Ian to fix it properly
> > (currently on vacation). 
> 
> I'm currently looking at this but I'm not seeing this issue, xend starts
> up fine and I can start a (PV) VM.
> 
> When you said "segfault on startup" did you mean of xend or of a domain?
> (I think the former).
> 
> Can you give me a little more information about your environment please?
> Is it NetBSD by any chance?
> 
> Please could you reapply this changeset add some tracing to
> hcall_buf_prep and _xc_clean_hcall_buf to print out the hcall_buff and
> hcall_buff->buf as they are allocated and freed. The line numbers
> indicate that the free(hcall_buf->buf) is faulting. We've just called
> unlock_pages on the same address but since we seem to deliberately throw
> away any errors from munlock (see "safe_munlock") that doesn't really
> tell us much about its validity.
> 
> Perhaps this whole area needs looking at with an eye to NetBSD
> portability?
> 
 
I gave few days to Christoph to reply, I'll reapply the patch for now
but if Christoph can come up with a good explanation of the problem I'll
revert it again or fix the bug.


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