Re: [PATCH 04/12] mm: alloc_contig_freed_pages() added

From: Dave Hansen
Date: Thu Mar 31 2011 - 16:33:52 EST


On Thu, 2011-03-31 at 15:24 -0400, Steven Rostedt wrote:
> On Thu, Mar 31, 2011 at 08:58:03AM -0700, Dave Hansen wrote:
> > On Thu, 2011-03-31 at 15:16 +0200, Marek Szyprowski wrote:
> > >
> > > +unsigned long alloc_contig_freed_pages(unsigned long start, unsigned long end,
> > > + gfp_t flag)
> > > +{
> > > + unsigned long pfn = start, count;
> > > + struct page *page;
> > > + struct zone *zone;
> > > + int order;
> > > +
> > > + VM_BUG_ON(!pfn_valid(start));
> >
> > This seems kinda mean. Could we return an error? I understand that
> > this is largely going to be an early-boot thing, but surely trying to
> > punt on crappy input beats a full-on BUG().
> >
> > if (!pfn_valid(start))
> > return -1;
>
> But still keep the warning?
>
> if (WARN_ON(!pfn_valid(start))
> return -1;

Sure. You might also want to make sure you're respecting __GFP_NOWARN
if you're going to do that, or maybe just warn once per boot.


-- Dave

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