From: "Stephen C. Tweedie" <sct@redhat.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "Stephen C. Tweedie" <sct@redhat.com>,
"Benjamin C.R. LaHaise" <blah@kvack.org>,
Alexander Viro <viro@math.psu.edu>,
Richard F Weber <rfweber@link.com>,
linux-mm@kvack.org
Subject: Re: Hopefully a simple question on /proc/pid/mem
Date: Tue, 1 May 2001 10:36:31 +0100 [thread overview]
Message-ID: <20010501103631.J26638@redhat.com> (raw)
In-Reply-To: <m166flhnvy.fsf@frodo.biederman.org>; from ebiederm@xmission.com on Mon, Apr 30, 2001 at 07:13:53PM -0600
Hi,
On Mon, Apr 30, 2001 at 07:13:53PM -0600, Eric W. Biederman wrote:
> > Hint: think about what happens if you make a shared mapping of a
> > private proc/*/mem region...
>
> Now that we have reusable swap cache pages we could make it work
> correctly, except for the case of the first write a private mapping of
> file. Not that we would want to...
Think about fork. If a parent forks and then touches a private page
before the child does, it's the parent which gets a new page. The
supposed shared mmap of the parent now points to the child's page, not
the parent's. COW basically just can't do the right thing if a page
is both shared and private at the same time.
--Stephen
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next prev parent reply other threads:[~2001-05-01 9:36 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-04-30 18:17 Hopefully a simple question on /proc/pid/mem Richard F Weber
2001-04-30 18:50 ` Stephen C. Tweedie
2001-04-30 19:00 ` Alexander Viro
2001-04-30 19:02 ` Benjamin C.R. LaHaise
2001-04-30 19:26 ` Alexander Viro
2001-04-30 19:26 ` Benjamin C.R. LaHaise
2001-04-30 19:44 ` Alexander Viro
2001-04-30 21:58 ` Stephen C. Tweedie
2001-05-01 1:13 ` Eric W. Biederman
2001-05-01 9:36 ` Stephen C. Tweedie [this message]
2001-05-01 15:16 ` Eric W. Biederman
2001-04-30 19:13 ` Richard F Weber
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