Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754945Ab1FFQWe (ORCPT ); Mon, 6 Jun 2011 12:22:34 -0400 Received: from mail-wy0-f174.google.com ([74.125.82.174]:43346 "EHLO mail-wy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753635Ab1FFQWd (ORCPT ); Mon, 6 Jun 2011 12:22:33 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=subject:from:to:cc:in-reply-to:references:content-type:date :message-id:mime-version:x-mailer:content-transfer-encoding; b=eD0DBWUWFmn82IwbgQ4aGf97Bw1Dwn9WNSXgKvkPGQFIPNCA2INYTp1BqoHFFw7SSb 5XSnnogTrQsDZ8oLUTn42g7iKBxIYGmYQzULuK+bS5YYxFbhwqRuhuuKqfOYMlZF0Sa+ Wn9pjQAIFW3c0KxcTsNfdNObQPEoNqGEt+1s4= Subject: Re: Change in functionality of futex() system call. From: Eric Dumazet To: Peter Zijlstra Cc: David Oliver , linux-kernel@vger.kernel.org, Shawn Bohrer , Zachary Vonler , KOSAKI Motohiro , Hugh Dickins , Thomas Gleixner , Darren Hart , Ingo Molnar In-Reply-To: <1307376989.2322.171.camel@twins> References: <1307373819.3098.40.camel@edumazet-laptop> <1307376672.2322.167.camel@twins> <1307376989.2322.171.camel@twins> Content-Type: text/plain; charset="UTF-8" Date: Mon, 06 Jun 2011 18:22:29 +0200 Message-ID: <1307377349.3098.65.camel@edumazet-laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.32.2 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 768 Lines: 22 Le lundi 06 juin 2011 à 18:16 +0200, Peter Zijlstra a écrit : > Hmm, wouldn't that still be susceptible to the zero-page thing if: we > create a writable private file map of a sparse file, touch a page and > then remap the thing RO? > > > Also I am not sure how MAP_PRIVATE could be affected. If we still try a RW gup()... It will allocate a page for us, instead of still pointing to shared one. On previous kernel, the application using read-only mapping could use MAP_PRIVATE or MAP_SHARED with same 'behavior' -- 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/