From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262840AbUBZQuL (ORCPT ); Thu, 26 Feb 2004 11:50:11 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262844AbUBZQuL (ORCPT ); Thu, 26 Feb 2004 11:50:11 -0500 Received: from chaos.analogic.com ([204.178.40.224]:4737 "EHLO chaos.analogic.com") by vger.kernel.org with ESMTP id S262840AbUBZQs0 (ORCPT ); Thu, 26 Feb 2004 11:48:26 -0500 Date: Thu, 26 Feb 2004 11:50:27 -0500 (EST) From: "Richard B. Johnson" X-X-Sender: root@chaos Reply-To: root@chaos.analogic.com To: Willy Tarreau cc: Marcelo Tosatti , linux-kernel@vger.kernel.org Subject: Re: [BUG][2.4] /proc/kcore is a random generator ? In-Reply-To: <20040226161637.GA4201@alpha.home.local> Message-ID: References: <200402181337.i1IDbsXU010467@hera.kernel.org> <20040226161637.GA4201@alpha.home.local> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 26 Feb 2004, Willy Tarreau wrote: > Hi all, > > I'm encountering a rather strange behaviour here with 2.4.25 on a P4 HT, > even when I boot it with "nosmp" : > - du /proc/kcore says '525255' (I have 512 MB RAM) > - if I do it again many several times, sometimes it says '0' > - after a moment (or several tests, I don't know), it stabilizes to some > value (either 0 or 525255). > - then, just starting vmstat, or logging into the system is enough to > make it switch to the other value. > > At first, I had the feeling that it displayed '0' when I have an even number > of processes, and 525255 when I have an odd number, but it's not even the case. > Once it doesn't move by itself, a few fork/exec are enough to switch the value. > > If I boot in HT mode, sometimes I can reliably make it display 0 and 525255 > alternatively, just as if the pid parity or CPU number was involved in the > result. > > Update: same results with 2.4.26-pre1. du from coreutils 4.5.4 and 5.0. > > This is amazing. Did anyone notice this ? A friend just told me that plain > 2.4.22 on his notebook does the same ! > > Regards, > Willy > Well with 'older' utilities on 2.4.24, I always get '0' with `du`! Script started on Thu Feb 26 11:48:23 2004 # du /proc/kcore 0 /proc/kcore # ls -la /proc/kcore -r-------- 1 root root 335536128 Feb 26 11:48 /proc/kcore # exit exit Script done on Thu Feb 26 11:48:43 2004 Probably moon-phase. Cheers, Dick Johnson Penguin : Linux version 2.4.24 on an i686 machine (797.90 BogoMips). Note 96.31% of all statistics are fiction.