XFS memory allocation deadlock in 2.6.38

['Christoph Hellwig']

On Tue, Mar 29, 2011 at 09:39:07PM +0200, Johannes Weiner wrote:
> > -	ptr = vmalloc(size);
> > +	ptr = __vmalloc(size, GFP_NOFS | __GFP_HIGHMEM, PAGE_KERNEL);
> >  	if (ptr)
> >  		memset(ptr, 0, size);
> >  	return ptr;
> 
> Note that vmalloc is currently broken in that it does a GFP_KERNEL
> allocation if it has to allocate page table pages, even when invoked
> with GFP_NOFS:
> 
> 	http://marc.info/?l=linux-mm&m=128942194520631&w=4

Oh great.  In that case we had a chance to hit the deadlock even before
the offending commit, just a much smaller one.