From: Pekka Enberg <penberg@kernel.org>
To: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Christoph Lameter <cl@linux-foundation.org>,
Matt Mackall <mpm@selenic.com>
Subject: Re: Memory allocator semantics
Date: Tue, 11 Feb 2014 10:50:24 +0200 [thread overview]
Message-ID: <CAOJsxLHs890eypzfnNj4ff1zqy_=bC8FA7B0YYbcZQF_c_wSog@mail.gmail.com> (raw)
In-Reply-To: <20140209020004.GY4250@linux.vnet.ibm.com>
Hi Paul,
On Sun, Feb 9, 2014 at 4:00 AM, Paul E. McKenney
<paulmck@linux.vnet.ibm.com> wrote:
> From what I can see, (A) works by accident, but is kind of useless because
> you allocate and free the memory without touching it. (B) and (C) are the
> lightest touches I could imagine, and as you say, both are bad. So I
> believe that it is reasonable to prohibit (A).
>
> Or is there some use for (A) that I am missing?
So again, there's nothing in (A) that the memory allocator is
concerned about. kmalloc() makes no guarantees whatsoever about the
visibility of "r1" across CPUs. If you're saying that there's an
implicit barrier between kmalloc() and kfree(), that's an unintended
side-effect, not a design decision AFAICT.
Pekka
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2014-02-11 8:50 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-02 20:33 Memory allocator semantics Paul E. McKenney
2014-01-03 3:39 ` Josh Triplett
2014-01-03 5:14 ` Paul E. McKenney
2014-01-03 5:47 ` Josh Triplett
2014-01-03 7:57 ` Paul E. McKenney
2014-01-03 8:42 ` Josh Triplett
2014-02-08 10:27 ` Pekka Enberg
2014-02-09 2:00 ` Paul E. McKenney
2014-02-11 8:50 ` Pekka Enberg [this message]
2014-02-11 12:09 ` Paul E. McKenney
2014-02-11 18:43 ` Christoph Lameter
2014-02-14 17:30 ` Paul E. McKenney
2014-02-10 19:07 ` Christoph Lameter
2014-02-11 12:14 ` Paul E. McKenney
2014-02-11 13:20 ` Pekka Enberg
2014-02-11 15:01 ` Paul E. McKenney
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='CAOJsxLHs890eypzfnNj4ff1zqy_=bC8FA7B0YYbcZQF_c_wSog@mail.gmail.com' \
--to=penberg@kernel.org \
--cc=cl@linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mpm@selenic.com \
--cc=paulmck@linux.vnet.ibm.com \
/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;
as well as URLs for NNTP newsgroup(s).