linux-kernel - Re: Memory allocator semantics

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 11 Feb 2014 10:50:24 +0200
From:	Pekka Enberg <penberg@...nel.org>
To:	Paul McKenney <paulmck@...ux.vnet.ibm.com>
Cc:	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Christoph Lameter <cl@...ux-foundation.org>,
	Matt Mackall <mpm@...enic.com>
Subject: Re: Memory allocator semantics

Hi Paul,

On Sun, Feb 9, 2014 at 4:00 AM, Paul E. McKenney
<paulmck@...ux.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 from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/