Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754666Ab0DSRRe (ORCPT ); Mon, 19 Apr 2010 13:17:34 -0400 Received: from mx1.redhat.com ([209.132.183.28]:11731 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754456Ab0DSRRc (ORCPT ); Mon, 19 Apr 2010 13:17:32 -0400 Date: Mon, 19 Apr 2010 18:32:17 +0200 From: Andrea Arcangeli To: Peter Zijlstra Cc: Mel Gorman , r6144 , linux-kernel@vger.kernel.org, Darren Hart , tglx , Lee Schermerhorn Subject: Re: Process-shared futexes on hugepages puts the kernel in an infinite loop in 2.6.32.11; is this fixed now? Message-ID: <20100419163217.GB32034@random.random> References: <1271432722.2564.16.camel@localhost.localdomain> <1271449668.1674.466.camel@laptop> <20100419114300.GT19264@csn.ul.ie> <1271677956.1674.922.camel@laptop> <20100419153245.GX19264@csn.ul.ie> <1271691905.1488.317.camel@laptop> <20100419161102.GZ32034@random.random> <1271693928.1676.18.camel@laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1271693928.1676.18.camel@laptop> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1058 Lines: 21 On Mon, Apr 19, 2010 at 06:18:48PM +0200, Peter Zijlstra wrote: > Well, most poison values have that problem and still we have them. Also That would better be fixed too to stay <4096 for higher chance of bug-detection, it doesn't make this case correct ;). > on 64bit machines you can use POISON_POINTER_DELTA to map it outside the > virtual address range. We've thousands of magic values there, I don't see much benefit from POISON_POINTER_DELTA other than being able to call it 0xdeadbeef+POISON_POINTER_DELTA ;). We always look the assembly to find the actual real raw pointer value (without the field offset) so I think using a range between 0xaaa and 0xbbb for the error pointers, is functional enough, but it's up to you as long as it is a address range that can't be used by userland it's surely ok ;). -- 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/