From: Ethan Solomita <solo@google.com>
To: Hugh Dickins <hugh@veritas.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>, linux-mm@kvack.org
Subject: Re: page_referenced() and VM_LOCKED
Date: Tue, 04 Dec 2007 16:26:41 -0800 [thread overview]
Message-ID: <4755F041.4000605@google.com> (raw)
In-Reply-To: <Pine.LNX.4.64.0711161749020.12201@blonde.wat.veritas.com>
Hugh Dickins wrote:
> On Fri, 16 Nov 2007, KAMEZAWA Hiroyuki wrote:
>> On Thu, 15 Nov 2007 20:25:45 -0800
>> Ethan Solomita <solo@google.com> wrote:
>>
>>> page_referenced_file() checks for the vma to be VM_LOCKED|VM_MAYSHARE
>>> and adds returns 1.
>
> That's a case where it can deduce that the page is present and should
> be treated as referenced, without even examining the page tables.
>
>>> We don't do the same in page_referenced_anon().
>
> It cannot make that same deduction in the page_referenced_anon() case
> (different vmas may well contain different COWs of some original page).
Sorry to come back in with this so late -- if the vma is VM_MAYSHARE,
would there be COWs of the original page?
-- Ethan
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next prev parent reply other threads:[~2007-12-05 0:26 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-16 4:25 page_referenced() and VM_LOCKED Ethan Solomita
2007-11-16 5:46 ` KAMEZAWA Hiroyuki
2007-11-16 18:00 ` Hugh Dickins
2007-11-17 0:32 ` kamezawa.hiroyu
2007-11-19 9:39 ` KAMEZAWA Hiroyuki
2007-11-19 19:09 ` Hugh Dickins
2007-12-05 0:26 ` Ethan Solomita [this message]
2007-12-05 15:54 ` Hugh Dickins
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