From: David Miller <davem@davemloft.net>
To: aneesh.kumar@linux.vnet.ibm.com
Cc: aarcange@redhat.com, linux-arch@vger.kernel.org,
steve.capper@linaro.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, akpm@linux-foundation.org,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH V4 1/2] mm: Update generic gup implementation to handle hugepage directory
Date: Sat, 01 Nov 2014 15:21:12 -0400 (EDT) [thread overview]
Message-ID: <20141101.152112.741323581543029110.davem@davemloft.net> (raw)
In-Reply-To: <1414570785-18966-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com>
From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Date: Wed, 29 Oct 2014 13:49:44 +0530
> Update generic gup implementation with powerpc specific details.
> On powerpc at pmd level we can have hugepte, normal pmd pointer
> or a pointer to the hugepage directory.
>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> ---
> Changes from V3:
> * Drop arm and arm64 changes
> * Add hugepte assumption to the function
Wait, what are you doing here?
You can't assume that a pmd is something you can just go:
__pte(pmd_val(x))
with. Not at all.
You have to use the correct pmd_*() accessors at all times on
this object.
Platforms can encode PMDs however they like. In fact, on sparc64,
we used to have 32-bit PMDs with a special encoding for huge
PMDs that looked nothing at all like a 64-bit PTE.
Please code this in a portable manner to support the powerpc
facilities, don't add assumptions that are not necessarily
universally true.
prev parent reply other threads:[~2014-11-01 19:21 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-29 8:19 [PATCH V4 1/2] mm: Update generic gup implementation to handle hugepage directory Aneesh Kumar K.V
2014-10-29 8:19 ` [PATCH V4 2/2] arch/powerpc: Switch to generic RCU get_user_pages_fast Aneesh Kumar K.V
2014-10-29 9:25 ` [PATCH V4 1/2] mm: Update generic gup implementation to handle hugepage directory Steve Capper
2014-11-01 18:05 ` David Miller
2014-11-01 19:21 ` David Miller [this message]
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