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From: Dave Hansen <dave@linux.vnet.ibm.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: mpm@selenic.com, hans.rosenfeld@amd.com, linux-mm@kvack.org,
	hugh@veritas.com, riel@redhat.com, nacc <nacc@linux.vnet.ibm.com>,
	Adam Litke <agl@linux.vnet.ibm.com>
Subject: Re: [v4][PATCH 2/2] fix large pages in pagemap
Date: Wed, 11 Jun 2008 14:23:55 -0700	[thread overview]
Message-ID: <1213219435.20475.44.camel@nimitz> (raw)
In-Reply-To: <20080611135207.32a46267.akpm@linux-foundation.org>

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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  parent reply	other threads:[~2008-06-11 21:23 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-06-11 18:02 [v4][PATCH 1/2] pass mm into pagewalkers Dave Hansen
2008-06-11 18:02 ` [v4][PATCH 2/2] fix large pages in pagemap Dave Hansen
2008-06-11 19:37   ` Andrew Morton
2008-06-11 19:53     ` Matt Mackall
2008-06-11 20:11       ` Andrew Morton
2008-06-11 20:21         ` Matt Mackall
2008-06-11 20:34         ` Dave Hansen
2008-06-11 20:52           ` Andrew Morton
2008-06-11 21:01             ` Rik van Riel
2008-06-11 21:23             ` Dave Hansen [this message]
2008-06-11 22:37               ` Matt Mackall
2008-06-12 21:36                 ` Hugh Dickins
2008-06-12 22:35                   ` Matt Mackall
2008-06-11 20:15       ` Dave Hansen
2008-06-11 19:35 ` [v4][PATCH 1/2] pass mm into pagewalkers Andrew Morton

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