From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f43.google.com (mail-pa0-f43.google.com [209.85.220.43]) by kanga.kvack.org (Postfix) with ESMTP id 07D636B00D2 for ; Tue, 22 Oct 2013 11:22:11 -0400 (EDT) Received: by mail-pa0-f43.google.com with SMTP id hz1so7994962pad.30 for ; Tue, 22 Oct 2013 08:22:11 -0700 (PDT) Received: from psmtp.com ([74.125.245.143]) by mx.google.com with SMTP id ph6si11991471pbb.7.2013.10.22.08.22.10 for ; Tue, 22 Oct 2013 08:22:11 -0700 (PDT) Message-ID: <526697F5.7040800@intel.com> Date: Tue, 22 Oct 2013 08:21:25 -0700 From: Dave Hansen MIME-Version: 1.0 Subject: Re: [PATCH] x86, mm: get ASLR work for hugetlb mappings References: <1382449940-24357-1-git-send-email-kirill.shutemov@linux.intel.com> In-Reply-To: <1382449940-24357-1-git-send-email-kirill.shutemov@linux.intel.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: "Kirill A. Shutemov" , Andrew Morton , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" Cc: Nadia Yvette Chambers , Naoya Horiguchi , x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Matthew Wilcox On 10/22/2013 06:52 AM, Kirill A. Shutemov wrote: > 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. I have to wonder if this was on purpose in order to keep the large and small mappings separate. We don't *have* to keep them separate this, of course, but it makes me wonder. > 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. Shouldn't we fix the generic code instead of further specializing the x86 stuff? In any case, you probably also want to run this through: the libhugetlbfs tests: http://sourceforge.net/p/libhugetlbfs/code/ci/master/tree/tests/ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org