Re: [Intel IOMMU 05/10] Intel IOMMU driver

[Andrew Morton <akpm@linux-foundation.org>]

On Tue, 19 Jun 2007 16:32:23 -0700 (PDT) Christoph Lameter <clameter@sgi.com> wrote:

> On Tue, 19 Jun 2007, Keshavamurthy, Anil S wrote:
> 
> > +static inline void *alloc_pgtable_page(void)
> > +{
> > +	return (void *)get_zeroed_page(GFP_ATOMIC);
> > +}
> 
> Need to pass gfp_t parameter. Repeates a couple of times.
> ...
> Is it not possible here to drop the lock and do the alloc with GFP_KERNEL 
> and deal with the resulting race? That is done in other parts of the 
> kernel.
> ...
> This may be able to become a GFP_KERNEL alloc since interrupts are enabled 
> at this point?
> ...
> GFP_KERNEL alloc possible?
> 

Yeah, if there are any callsites at all at which we know that we can
perform a sleeping allocation, Christoph's suggestions should be adopted. 
Because even a bare GFP_NOIO is heaps more robust than GFP_ATOMIC, and it
will also reload the free-pages reserves, making subsequent GFP_ATOMIC
allocations more likely to succeed.