Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267561AbTHOVwU (ORCPT ); Fri, 15 Aug 2003 17:52:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267520AbTHOVwU (ORCPT ); Fri, 15 Aug 2003 17:52:20 -0400 Received: from marblerye.cs.uga.edu ([128.192.101.172]:16000 "HELO marblerye.cs.uga.edu") by vger.kernel.org with SMTP id S267561AbTHOVwK (ORCPT ); Fri, 15 Aug 2003 17:52:10 -0400 To: Ed L Cashin Cc: linux-kernel , Linus Torvalds , Rusty Russell Subject: Re: [PATCH] do_wp_page: BUG on invalid pfn References: <20030815184720.A4D482CE79@lists.samba.org> <877k5e8vwe.fsf@uga.edu> <20030815212244.GQ1027@matchmail.com> From: Ed L Cashin Date: Fri, 15 Aug 2003 17:52:09 -0400 Message-ID: <87k79e7fna.fsf@uga.edu> User-Agent: Gnus/5.090014 (Oort Gnus v0.14) Emacs/21.2 (i386-debian-linux-gnu) 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 Content-Length: 2041 Lines: 58 Mike Fedyk writes: > On Fri, Aug 15, 2003 at 05:15:45PM -0400, Ed L Cashin wrote: >> Rusty Russell writes: >> >> > In message <87d6fixvpm.fsf@uga.edu> you write: >> >> This patch just does what the comment says should be done. >> > >> > Hi Ed! >> > >> > Not trivial I'm afraid. Send to Linus and lkml. >> >> >> This patch just does what the comment says should be done. I thought >> it was a trivial patch, but Rusty Russell has informed me otherwise. >> (Thanks, RR). >> >> >> --- linux-2.6.0-test2/mm/memory.c.orig Sun Jul 27 13:01:24 2003 >> +++ linux-2.6.0-test2/mm/memory.c Wed Aug 6 18:30:55 2003 >> @@ -990,15 +990,10 @@ >> int ret; >> >> if (unlikely(!pfn_valid(pfn))) { >> - /* >> - * This should really halt the system so it can be debugged or >> - * at least the kernel stops what it's doing before it corrupts >> - * data, but for the moment just pretend this is OOM. >> - */ >> - pte_unmap(page_table); >> printk(KERN_ERR "do_wp_page: bogus page at address %08lx\n", >> address); >> - goto oom; >> + dump_stack(); >> + BUG(); > > You're not unmapping the pte I guess to not interfere with the dump_stack, This patch changes the logic from "pretend it's out of memory" to "announce something's very wrong and bail out right away." Unmapping the pte seems like a precursor to carrying on business as usual, but there must be some subtleties here that I am unaware of, or Rusty Russell wouldn't have called this patch non-trivial. > but what about the printk? Will that affect the dump_stack also? It seems like you'd return from the printk before dumping the stack, so I wouldn't think so. -- --Ed L Cashin | PGP public key: ecashin@uga.edu | http://noserose.net/e/pgp/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/