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From: Rik van Riel <riel@redhat.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Hugh Dickins <hughd@google.com>, Christoph Lameter <cl@linux.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Peter Zijlstra <peterz@infradead.org>,
	linux-mm <linux-mm@kvack.org>
Subject: Re: [PATCH 1/4] hugetlb, rmap: always use anon_vma root pointer
Date: Fri, 10 Sep 2010 22:09:32 -0400	[thread overview]
Message-ID: <4C8AE4DC.3030308@redhat.com> (raw)
In-Reply-To: <20100910235022.74ec04de@basil.nowhere.org>

On 09/10/2010 05:50 PM, Andi Kleen wrote:
> On Fri, 10 Sep 2010 10:19:24 -0700
> Linus Torvalds<torvalds@linux-foundation.org>  wrote:
>
>> On Thu, Sep 9, 2010 at 9:23 PM, Naoya Horiguchi
>> <n-horiguchi@ah.jp.nec.com>  wrote:
>>> This patch applies Andrea's fix given by the following patch into
>>> hugepage rmapping code:
>>>
>>>   commit 288468c334e98aacbb7e2fb8bde6bc1adcd55e05
>>>   Author: Andrea Arcangeli<aarcange@redhat.com>
>>>   Date:   Mon Aug 9 17:19:09 2010 -0700
>>>
>>> This patch uses anon_vma->root and avoids unnecessary overwriting
>>> when anon_vma is already set up.
>>
>> Btw, why isn't the code in __page_set_anon_rmap() also doing this
>> cleaner version (ie a single "if (PageAnon(page)) return;" up front)?
>
> Perhaps I misunderstand the question, but __page_set_anon_rmap
> should handle Anon pages, shouldn't it?

__page_set_anon_rmap sets the page->mapping to be
a pointer to the anon_vma & PAGE_MAPPING_ANON.

PageAnon tests for page->mapping & PAGE_MAPPING_ANON,
ie. whether page->mapping is already pointing to an
anon_vma.

If it is, __page_set_anon_rmap should leave the page
mapping pointer alone.

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  parent reply	other threads:[~2010-09-11  2:09 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-09-10  4:23 [PATCH 0/4] hugetlb, rmap: fixes and cleanups Naoya Horiguchi
2010-09-10  4:23 ` [PATCH 1/4] hugetlb, rmap: always use anon_vma root pointer Naoya Horiguchi
2010-09-10 14:37   ` Andrea Arcangeli
2010-09-10 14:40   ` Rik van Riel
2010-09-10 17:19   ` Linus Torvalds
2010-09-10 21:50     ` Andi Kleen
2010-09-10 22:07       ` Linus Torvalds
2010-09-11  2:09       ` Rik van Riel [this message]
2010-09-10  4:23 ` [PATCH 2/4] hugetlb, rmap: use hugepage_add_new_anon_rmap() in hugetlb_cow() Naoya Horiguchi
2010-09-10 14:39   ` Andrea Arcangeli
2010-09-10 14:40   ` Rik van Riel
2010-09-10  4:23 ` [PATCH 3/4] hugetlb, rmap: fix confusing page locking " Naoya Horiguchi
2010-09-10 14:41   ` Rik van Riel
2010-09-10 17:15   ` Linus Torvalds
2010-09-23 23:50     ` Naoya Horiguchi
2010-09-10  4:23 ` [PATCH 4/4] hugetlb, rmap: add BUG_ON(!PageLocked) in hugetlb_add_anon_rmap() Naoya Horiguchi
2010-09-10 14:42   ` Rik van Riel
2010-09-10 14:44   ` Andrea Arcangeli
2010-09-10  9:04 ` [PATCH 0/4] hugetlb, rmap: fixes and cleanups Andi Kleen
2010-09-10 11:47   ` Naoya Horiguchi
2010-09-10 14:30     ` Andi Kleen

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