Re: [Xen-devel] Grant Table Network Issues

[David Hopwood <david.nospam.hopwood@xxxxxxxxxxxxxxxx>]

Michael Vrable wrote:
> On Sun, Aug 14, 2005 at 09:29:02AM +0100, Keir Fraser wrote:
> > On 13 Aug 2005, at 19:59, Michael Vrable wrote:
> >
> > > The line causing trouble is "BUG_ON(in_irq())". [...]
> > The only code between irq_exit and kmap_skb_frag on the stack trace is 
> > unmodified Linux code. Assuming that is all correct (and presumably the 
> > same whether we enable grant tables or not) I might guess another 
> > interrupt arrives and the handler corrupts things?
> I discovered the cause of this and other crashes yesterday: when grant
> tables are enabled in the netback driver, net_tx_action() and
> net_tx_action_dealloc() in netback.c each allocate large arrays from the
> kernel's stack ("gnttab_map_grant_ref_t map_ops[MAX_PENDING_REQS]" and
> "gnttab_unmap_grant_ref_t unmap_ops[MAX_PENDING_REQS]").  This results
> in a stack overflow.
Is there no way to make a kernel stack overflow fail fast with an obvious
error, rather than causing other subtle failures?

--
David Hopwood <david.nospam.hopwood@xxxxxxxxxxxxxxxx>


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