Re: [v4][PATCH 2/2] fix large pages in pagemap

[Dave Hansen <dave@linux.vnet.ibm.com>]

On Wed, 2008-06-11 at 13:52 -0700, Andrew Morton wrote:
> access_process_vm-device-memory-infrastructure.patch is a powerpc
> feature, and it uses pmd_huge().

I think that's bogus.  It probably needs to check the VMA in
generic_access_phys() if it wants to be safe.  I don't see any way that
pmd_huge() can give anything back other than 0 on ppc:

arch/powerpc/mm/hugetlbpage.c:

	int pmd_huge(pmd_t pmd)
	{
	        return 0;
	}

or in include/linux/hugetlb.h:

	#define pmd_huge(x)     0

> Am I missing something, or is pmd_huge() a whopping big grenade for x86
> developers to toss at non-x86 architectures?  It seems quite dangerous.

Yeah, it isn't really usable outside of arch code, although it kinda
looks like it.

-- Dave

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