From owner-freebsd-hackers Thu Aug 22 22:19:24 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.FreeBSD.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 152CC37B400 for ; Thu, 22 Aug 2002 22:19:22 -0700 (PDT) Received: from critter.freebsd.dk (critter.freebsd.dk [212.242.86.163]) by mx1.FreeBSD.org (Postfix) with ESMTP id 2F75343E72 for ; Thu, 22 Aug 2002 22:19:21 -0700 (PDT) (envelope-from phk@critter.freebsd.dk) Received: from critter.freebsd.dk (localhost [127.0.0.1]) by critter.freebsd.dk (8.12.3/8.12.2) with ESMTP id g7N5Froc016197; Fri, 23 Aug 2002 07:15:56 +0200 (CEST) (envelope-from phk@critter.freebsd.dk) To: "Un, SungKyong" Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: userland malloc() and zeroed page allocation in Kernel In-Reply-To: Your message of "Fri, 23 Aug 2002 11:09:07 +0900." <001601c24a4a$121fbb60$1bf2fe81@etri.re.kr> Date: Fri, 23 Aug 2002 07:15:53 +0200 Message-ID: <16196.1030079753@critter.freebsd.dk> From: Poul-Henning Kamp Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG In message <001601c24a4a$121fbb60$1bf2fe81@etri.re.kr>, "Un, SungKyong" writes: >But when I try to test this, something strange happed. > > for (i=0; i<200;i++) { > malloc(1MB); > check it's all zeroed; > set this block to 'X'; > } > free all allocated memory(200MB); > for (i=0; i<200;i++) { > malloc(1MB); > check it's all 'X'; > } You cannot trust the value of memory you have free(3)'ed to stay until you malloc(3) again. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message