From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f42.google.com (mail-wg0-f42.google.com [74.125.82.42]) by kanga.kvack.org (Postfix) with ESMTP id 0ED196B006C for ; Tue, 18 Nov 2014 16:15:33 -0500 (EST) Received: by mail-wg0-f42.google.com with SMTP id z12so10789887wgg.1 for ; Tue, 18 Nov 2014 13:15:32 -0800 (PST) Received: from one.firstfloor.org (one.firstfloor.org. [193.170.194.197]) by mx.google.com with ESMTPS id cw3si23030534wib.52.2014.11.18.13.15.32 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Tue, 18 Nov 2014 13:15:32 -0800 (PST) Date: Tue, 18 Nov 2014 22:15:31 +0100 From: Andi Kleen Subject: Re: [PATCH v6 00/11] Kernel address sanitizer - runtime memory debugger. Message-ID: <20141118211531.GH12538@two.firstfloor.org> References: <1404905415-9046-1-git-send-email-a.ryabinin@samsung.com> <1415199241-5121-1-git-send-email-a.ryabinin@samsung.com> <5461B906.1040803@samsung.com> <20141118125843.434c216540def495d50f3a45@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141118125843.434c216540def495d50f3a45@linux-foundation.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Andrey Ryabinin , Dmitry Vyukov , Konstantin Serebryany , Dmitry Chernenkov , Andrey Konovalov , Yuri Gribov , Konstantin Khlebnikov , Sasha Levin , Michal Marek , Thomas Gleixner , Ingo Molnar , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Dave Hansen , Andi Kleen , Vegard Nossum , "H. Peter Anvin" , x86@kernel.org, linux-mm@kvack.org, Randy Dunlap , Peter Zijlstra , Alexander Viro , Dave Jones , Jonathan Corbet , Joe Perches , linux-kernel@vger.kernel.org > It's a huge pile of tricky code we'll need to maintain. To justify its > inclusion I think we need to be confident that kasan will find a > significant number of significant bugs that > kmemcheck/debug_pagealloc/slub_debug failed to detect. I would put it differently. kmemcheck is effectively too slow to run regularly. kasan is much faster and covers most of kmemcheck. So I would rather see it as a more practical replacement to kmemcheck, not an addition. > How do we get that confidence? I've seen a small number of > minorish-looking kasan-detected bug reports go past, maybe six or so. > That's in a 20-year-old code base, so one new minor bug discovered per > three years? Not worth it! > > Presumably more bugs will be exposed as more people use kasan on > different kernel configs, but will their number and seriousness justify > the maintenance effort? I would expect so. It's also about saving developer time. IMHO getting better tools like this is the only way to keep up with growing complexity. > If kasan will permit us to remove kmemcheck/debug_pagealloc/slub_debug > then that tips the balance a little. What's the feasibility of that? Maybe removing kmemcheck. slub_debug/debug_pagealloc are simple, and are in different niches (lower overhead debugging) -Andi -- ak@linux.intel.com -- Speaking for myself only. -- 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