From: Jeff Dike <jdike@addtoit.com>
To: John Reiser <jreiser@BitWagon.com>
Cc: user-mode-linux-devel@lists.sourceforge.net
Subject: Re: [uml-devel] why allocate page for stack in clone(, stack, ~CLONE_VM & (...)) ?
Date: Thu, 1 Nov 2007 22:25:40 -0400 [thread overview]
Message-ID: <20071102022540.GA12253@c2.user-mode-linux.org> (raw)
In-Reply-To: <472A4DAC.3060104@BitWagon.com>
On Thu, Nov 01, 2007 at 03:05:32PM -0700, John Reiser wrote:
> In arch/um/os/start_up.c, function start_ptraced_child() does:
> pid = clone(ptrace_child, (void *) sp, SIGCHLD, NULL);
> where sp points into a newly- mmap()ed page. Instead, why not
> avoid the mmap() entirely via:
> pid = clone(ptrace_child, NULL, SIGCHLD, NULL);
>
> Because the flags to clone() do not contain CLONE_VM, then the clone()
> is equivalent to a fork() with respect to address space.
If you look at what's currently in mainline, you'll see it does
exactly what you suggest - the patch in question is this one:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=3cdaf45578b9aa1eb748d0a32678ee5a0180575b
Jeff
--
Work email - jdike at linux dot intel dot com
-------------------------------------------------------------------------
This SF.net email is sponsored by: Splunk Inc.
Still grepping through log files to find problems? Stop.
Now Search log events and configuration files using AJAX and a browser.
Download your FREE copy of Splunk now >> http://get.splunk.com/
_______________________________________________
User-mode-linux-devel mailing list
User-mode-linux-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel
prev parent reply other threads:[~2007-11-02 2:25 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-01 22:05 [uml-devel] why allocate page for stack in clone(, stack, ~CLONE_VM & (...)) ? John Reiser
2007-11-02 2:25 ` Jeff Dike [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20071102022540.GA12253@c2.user-mode-linux.org \
--to=jdike@addtoit.com \
--cc=jreiser@BitWagon.com \
--cc=user-mode-linux-devel@lists.sourceforge.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox