From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752008Ab3KSIbA (ORCPT ); Tue, 19 Nov 2013 03:31:00 -0500 Received: from mail-ea0-f172.google.com ([209.85.215.172]:40365 "EHLO mail-ea0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751310Ab3KSIa5 (ORCPT ); Tue, 19 Nov 2013 03:30:57 -0500 Date: Tue, 19 Nov 2013 09:30:53 +0100 From: Ingo Molnar To: akpm@linux-foundation.org Cc: mingo@elte.hu, hpa@zytor.com, tglx@linutronix.de, kirill.shutemov@linux.intel.com, dave.hansen@intel.com, mingo@redhat.com, n-horiguchi@ah.jp.nec.com, willy@linux.intel.com, linux-kernel@vger.kernel.org Subject: Re: [patch 3/3] x86, mm: get ASLR work for hugetlb mappings Message-ID: <20131119083053.GB1243@gmail.com> References: <20131115221406.1692E1E418F@corp2gmr1-2.eem.corp.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131115221406.1692E1E418F@corp2gmr1-2.eem.corp.google.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * akpm@linux-foundation.org wrote: > From: "Kirill A. Shutemov" > Subject: x86, mm: get ASLR work for hugetlb mappings > > Matthew noticed that hugetlb doesn't participate in ASLR on x86-64. The > reason is genereic hugetlb_get_unmapped_area() which is used on x86-64. > It doesn't support randomization and use bottom-up unmapped area lookup, > instead of usual top-down on x86-64. > > x86 has arch-specific hugetlb_get_unmapped_area(), but it's used only on > x86-32. > > Let's use arch-specific hugetlb_get_unmapped_area() on x86-64 too. It > fixes the issue and make hugetlb use top-down unmapped area lookup. So the title and the changelog has typos (I counted three), which makes me wonder how well this was tested. To show/document the testing effort a before/after /proc/PID/maps output showing hugetlb vma addresses would be nice, showing that ASLR didn't work before and that it works adequately after the patch. A word about the range and granularity of randomization in the typical case would be nice as well. Thanks, Ingo