Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964959AbWHHPg0 (ORCPT ); Tue, 8 Aug 2006 11:36:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964960AbWHHPg0 (ORCPT ); Tue, 8 Aug 2006 11:36:26 -0400 Received: from ug-out-1314.google.com ([66.249.92.170]:41897 "EHLO ug-out-1314.google.com") by vger.kernel.org with ESMTP id S964959AbWHHPgZ (ORCPT ); Tue, 8 Aug 2006 11:36:25 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=A4lH7EjTopy2yUeHcJriPA2T7b1jAc3kpSDJOJhvATN4y7JtmSEkkagrVpYPyZju6CVWWHIUlYulacIZYpaBFMq3rsV5oyB3RDLcVs9AyteP+QwiU18MQ6yF6rWJ4s4zUCXY3PTTb94gSKZZQaNRgcQsbMUxmFfBuXHmSN7t87w= Message-ID: Date: Tue, 8 Aug 2006 08:36:23 -0700 From: "Ulrich Drepper" To: "Nick Piggin" Subject: Re: [RFC] NUMA futex hashing Cc: "Eric Dumazet" , "Andi Kleen" , "Ravikiran G Thirumalai" , "Shai Fultheim (Shai@scalex86.org)" , "pravin b shelar" , linux-kernel@vger.kernel.org In-Reply-To: <44D8A9BE.3050607@yahoo.com.au> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20060808070708.GA3931@localhost.localdomain> <200608081429.44497.dada1@cosmosbay.com> <200608081447.42587.ak@suse.de> <200608081457.11430.dada1@cosmosbay.com> <44D8A9BE.3050607@yahoo.com.au> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1032 Lines: 18 On 8/8/06, Nick Piggin wrote: > Let me get this straight: to insert a contended futex into your rbtree, > you need to hold the mmap sem to ensure that address remains valid, > then you need to take a lock which protects your rbtree. Why does it have to remain valid? As long as the kernel doesn't crash on any of the operations associated with the futex syscalls let the address space region explode, implode, whatever. It's a bug in the program if the address region is changed while a futex is placed there. If the futex syscall hangs forever or returns with a bogus state (error or even success) this is perfectly acceptable. We shouldn't slow down correct uses just to make it possible for broken programs to receive a more detailed error description. - 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/