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

[Michal Nazarewicz]

On Thu, 31 Mar 2011 17:58:03 +0200, Dave Hansen <dave@xxxxxxxxxxxxxxxxxx>  
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().

Actually, I would have to check but I think that the usage of this function
(in this patchset) is that the caller expects the function to succeed.  It  
is
quite a low-level function so before running it a lot of preparation is  
needed
and the caller must make sure that several conditions are met.  I don't  
really
see advantage of returning a value rather then BUG()ing.

Also, CMA does not call this function at boot time.

--
Best regards,                                         _     _
.o. | Liege of Serenely Enlightened Majesty of      o' \,=./ `o
..o | Computer Science,  Michal "mina86" Nazarewicz    (o o)
ooo +-----<email/xmpp: mnazarewicz@xxxxxxxxxx>-----ooO--(_)--Ooo--
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