From: Linus Torvalds <torvalds@linux-foundation.org>
To: Andi Kleen <andi@firstfloor.org>
Cc: 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>,
Rik van Riel <riel@redhat.com>,
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 15:07:08 -0700 [thread overview]
Message-ID: <AANLkTinFqM4BSD0jkrqkrNxg-o+3eC6QQ6zq8jKdaLJx@mail.gmail.com> (raw)
In-Reply-To: <20100910235022.74ec04de@basil.nowhere.org>
On Fri, Sep 10, 2010 at 2:50 PM, Andi Kleen <andi@firstfloor.org> wrote:
>> 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?
I'm talking about this:
if (!exclusive) {
if (PageAnon(page))
return;
anon_vma = anon_vma->root;
} else {
.. big bad comment ...
if (PageAnon(page))
return;
}
where both sides of the if-statement start off doing the same thing.
It would be much cleaner to just do
... big _comprehensible_ comment ...
if (PageAnon(page))
return;
if (!exclusive)
anon_vma = anon_vma->root;
which avoids that silly else that just does something that we always do.
The reason I reacted is that Naoya-san's patch did that cleaner
version for the hugetlb case. So when I compared it to the non-hugetlb
case I just went "Ewww..."
Linus
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next prev parent reply other threads:[~2010-09-10 22:08 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 [this message]
2010-09-11 2:09 ` Rik van Riel
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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