Re: [hugepage] Fix unmap_and_free_vma backout path

['David Gibson' <david@gibson.dropbear.id.au>]

On Sun, Nov 12, 2006 at 11:35:28PM -0800, Chen, Kenneth W wrote:
> David Gibson wrote on Sunday, November 12, 2006 10:23 PM
> > > > Probably, yes, although it's yet another "if (hugepage)
> > > > specialcase()".  But I still think we want the above patch as well.
> > > > It will make sure we correctly back out from any other possible
> > > > failure cases in hugetlbfs_file_mmap() - ones I haven't thought of, or
> > > > which get added later.
> > > 
> > > 
> > > Something like this?  I haven't tested it yet.  But looks plausible
> > > because we already have if is_file_hugepages() in the generic path.
> > 
> > Um.. if you're going to test pgoff here, you should also test the
> > address.
> 
> prepare_hugepage_range() should catch misaligned memory address, right?
> What more does get_unmapped_area() need to test?
> 
> 
> > Oh, and that point is too late to catch MAP_FIXED mappings.
> 
> I don't understand what you mean by that.

Sorry, old data.  I was thinking of the old get_unmapped_area() which
had entirely separate paths for MAP_FIXED and otherwise.  And I had my
sense inverted as well.

It used to be that prepare_hugepage_range() was called *only* in the
MAP_FIXED case (it being assumed that the hugetlb specific
get_unmapped_area call would do any necessary preparation).

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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