From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f47.google.com (mail-pa0-f47.google.com [209.85.220.47]) by kanga.kvack.org (Postfix) with ESMTP id E74D56B0032 for ; Fri, 30 Jan 2015 16:37:25 -0500 (EST) Received: by mail-pa0-f47.google.com with SMTP id lj1so56953321pab.6 for ; Fri, 30 Jan 2015 13:37:25 -0800 (PST) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id wq4si15145945pab.92.2015.01.30.13.37.24 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 30 Jan 2015 13:37:25 -0800 (PST) Date: Fri, 30 Jan 2015 13:37:23 -0800 From: Andrew Morton Subject: Re: [PATCH v10 02/17] x86_64: add KASan support Message-Id: <20150130133723.26e6e7f2b8e489a8640abd05@linux-foundation.org> In-Reply-To: <54CBAE2E.2030106@samsung.com> References: <1404905415-9046-1-git-send-email-a.ryabinin@samsung.com> <1422544321-24232-1-git-send-email-a.ryabinin@samsung.com> <1422544321-24232-3-git-send-email-a.ryabinin@samsung.com> <20150129151224.4e7947af78605c199763102c@linux-foundation.org> <54CBAE2E.2030106@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrey Ryabinin Cc: linux-kernel@vger.kernel.org, Dmitry Vyukov , Konstantin Serebryany , Dmitry Chernenkov , Andrey Konovalov , Yuri Gribov , Konstantin Khlebnikov , Sasha Levin , Christoph Lameter , Joonsoo Kim , Dave Hansen , Andi Kleen , x86@kernel.org, linux-mm@kvack.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Jonathan Corbet , Andy Lutomirski , "open list:DOCUMENTATION" On Fri, 30 Jan 2015 19:15:42 +0300 Andrey Ryabinin wrote: > >> --- a/lib/Kconfig.kasan > >> +++ b/lib/Kconfig.kasan > >> @@ -5,6 +5,7 @@ if HAVE_ARCH_KASAN > >> > >> config KASAN > >> bool "AddressSanitizer: runtime memory debugger" > >> + depends on !MEMORY_HOTPLUG > >> help > >> Enables address sanitizer - runtime memory debugger, > >> designed to find out-of-bounds accesses and use-after-free bugs. > > > > That's a significant restriction. It has obvious runtime implications. > > It also means that `make allmodconfig' and `make allyesconfig' don't > > enable kasan, so compile coverage will be impacted. > > > > This wasn't changelogged. What's the reasoning and what has to be done > > to fix it? > > > > Yes, this is runtime dependency. Hot adding memory won't work. > Since we don't have shadow for hotplugged memory, kernel will crash on the first access to it. > To fix this we need to allocate shadow for new memory. > > Perhaps it would be better to have a runtime warning instead of Kconfig dependecy? Is there a plan to get mem-hotplug working with kasan, btw? It doesn't strike me as very important/urgent. Please add a sentence about this to the changelog as well. -- 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