Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id <S131231AbQLIAcE>; Fri, 8 Dec 2000 19:32:04 -0500
Received: (majordomo@vger.kernel.org) by vger.kernel.org
	id <S130471AbQLIAb6>; Fri, 8 Dec 2000 19:31:58 -0500
Received: from vger.timpanogas.org ([207.109.151.240]:40714 "EHLO
	vger.timpanogas.org") by vger.kernel.org with ESMTP
	id <S131560AbQLIAbm>; Fri, 8 Dec 2000 19:31:42 -0500
Date: Fri, 8 Dec 2000 17:56:48 -0700
From: "Jeff V. Merkey" <jmerkey@vger.timpanogas.org>
To: David Woodhouse <dwmw2@infradead.org>
Cc: Mark Vojkovich <mvojkovich@valinux.com>, Andi Kleen <ak@suse.de>,
        Rainer Mager <rmager@vgkk.com>, linux-kernel@vger.kernel.org
Subject: Re: Signal 11
Message-ID: <20001208175648.A6588@vger.timpanogas.org>
In-Reply-To: <20001208161645.A6075@vger.timpanogas.org> <Pine.LNX.4.30.0012082224110.1210-100000@imladris.demon.co.uk>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
X-Mailer: Mutt 1.0.1i
In-Reply-To: <Pine.LNX.4.30.0012082224110.1210-100000@imladris.demon.co.uk>; from dwmw2@infradead.org on Fri, Dec 08, 2000 at 10:24:55PM +0000
Sender: linux-kernel-owner@vger.kernel.org
X-Mailing-List: linux-kernel@vger.kernel.org



I'll try.

Jeff


On Fri, Dec 08, 2000 at 10:24:55PM +0000, David Woodhouse wrote:
> On Fri, 8 Dec 2000, Jeff V. Merkey wrote:
> 
> > I have not seen it on UP systems either.  I only see it on SMP systems.
> > After trying very hard last night, I was able to get my 4 x PPro system to
> > do it with 2.4.0-12.  It seems related to loading in some way.  If you
> > have more than two processors, the loading is less since there's more
> > processors, and for whatever reason, it makes it harder to produce
> > whatever race condition is causing it.  I can get it to happen
> > pretty easily on a 2 x PII system.
> 
> Can you reproduce it with bcrl's patch below:
> 
> Index: mm/memory.c
> ===================================================================
> RCS file: /net/passion/inst/cvs/linux/mm/memory.c,v
> retrieving revision 1.2.2.40
> diff -u -r1.2.2.40 memory.c
> --- mm/memory.c	2000/12/05 13:33:39	1.2.2.40
> +++ mm/memory.c	2000/12/08 22:24:09
> @@ -860,6 +860,7 @@
>  	/*
>  	 * Ok, we need to copy. Oh, well..
>  	 */
> +	set_pte(page_table, pte);
>  	spin_unlock(&mm->page_table_lock);
>  	new_page = page_cache_alloc();
>  	if (!new_page)
> @@ -870,6 +871,12 @@
>  	 * Re-check the pte - we dropped the lock
>  	 */
>  	if (pte_same(*page_table, pte)) {
> +		/* We are changing the pte, so get rid of the old
> +		 * one to avoid races with the hardware, this really
> +		 * only affects the accessed bit here.
> +		 */
> +		pte = ptep_get_and_clear(page_table);
> +
>  		if (PageReserved(old_page))
>  			++mm->rss;
>  		break_cow(vma, old_page, new_page, address, page_table);
> @@ -1216,12 +1223,14 @@
>  		return do_swap_page(mm, vma, address, pte,
> pte_to_swp_entry(entry), write_access);
>  	}
> 
> +	entry = ptep_get_and_clear(pte);
>  	if (write_access) {
>  		if (!pte_write(entry))
>  			return do_wp_page(mm, vma, address, pte, entry);
> 
>  		entry = pte_mkdirty(entry);
>  	}
> +
>  	entry = pte_mkyoung(entry);
>  	establish_pte(vma, address, pte, entry);
>  	spin_unlock(&mm->page_table_lock);
> 
> 
> -- 
> dwmw2
> 
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
Please read the FAQ at http://www.tux.org/lkml/