From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0CE3FC433F5 for ; Tue, 14 Dec 2021 17:34:25 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 8086B6B0071; Tue, 14 Dec 2021 12:34:14 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 7B85D6B0073; Tue, 14 Dec 2021 12:34:14 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 658786B0074; Tue, 14 Dec 2021 12:34:14 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0169.hostedemail.com [216.40.44.169]) by kanga.kvack.org (Postfix) with ESMTP id 573A76B0071 for ; Tue, 14 Dec 2021 12:34:14 -0500 (EST) Received: from smtpin15.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 18D33181AC9C6 for ; Tue, 14 Dec 2021 17:34:04 +0000 (UTC) X-FDA: 78917098008.15.6A75D6A Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by imf11.hostedemail.com (Postfix) with ESMTP id D400540017 for ; Tue, 14 Dec 2021 17:34:01 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 93DE0B81BC9; Tue, 14 Dec 2021 17:34:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 90AF7C34606; Tue, 14 Dec 2021 17:33:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1639503240; bh=a14UGs1HcGFj82qfqT6BrA/2RMCLBg5mQx9AVEK4VpU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ZlNfM5dbjGpaDzMXebg0TsJnfkA5Czsy+vca92OsqdJw0F5cjEpoJo01rPHq/3rrJ fuW0NaLq+vFPwBn5y4KGLJi7jFsGXAmEkMaF9RuphWRETj7RucU3CpLTqB4osHXdNL UN20De1UpptLO/bPtLRtxHSyQ83o9UJY3Qwi2Is8= Date: Tue, 14 Dec 2021 18:33:57 +0100 From: Greg Kroah-Hartman To: Alexander Potapenko Cc: Alexander Viro , Andrew Morton , Andrey Konovalov , Andy Lutomirski , Ard Biesheuvel , Arnd Bergmann , Borislav Petkov , Christoph Hellwig , Christoph Lameter , David Rientjes , Dmitry Vyukov , Eric Dumazet , Herbert Xu , Ilya Leoshkevich , Ingo Molnar , Jens Axboe , Joonsoo Kim , Kees Cook , Marco Elver , Matthew Wilcox , "Michael S. Tsirkin" , Pekka Enberg , Peter Zijlstra , Petr Mladek , Steven Rostedt , Thomas Gleixner , Vasily Gorbik , Vegard Nossum , Vlastimil Babka , linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 41/43] security: kmsan: fix interoperability with auto-initialization Message-ID: References: <20211214162050.660953-1-glider@google.com> <20211214162050.660953-42-glider@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: D400540017 X-Stat-Signature: ni99b6d65bes99san689rt1gu5oe11np Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=linuxfoundation.org header.s=korg header.b=ZlNfM5db; dmarc=pass (policy=none) header.from=linuxfoundation.org; spf=pass (imf11.hostedemail.com: domain of gregkh@linuxfoundation.org designates 145.40.68.75 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org X-HE-Tag: 1639503241-669746 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Dec 14, 2021 at 06:00:41PM +0100, Alexander Potapenko wrote: > On Tue, Dec 14, 2021 at 5:38 PM Greg Kroah-Hartman > wrote: > > > > > @@ -124,6 +125,7 @@ choice > > > config INIT_STACK_ALL_ZERO > > > bool "zero-init everything (strongest and safest)" > > > depends on CC_HAS_AUTO_VAR_INIT_ZERO > > > + depends on !KMSAN > > > > So this means KMSAN is a developer debugging feature only and should > > never be turned on on a real device/server that has users? > > 100% correct. KMSAN is way slower than KASAN, it also eats 2/3 of your > memory to store the metadata. > I thought it was sort of self-evident, but I can surely mention this > explicitly in the cover letter. Please mention it here and in the Kconfig option for it as well (don't know if it was there or not.) Also you might want to print out very large "DO NOT USE THIS ON A REAL MACHINE" to the kernel log when booting, like other kernel options are starting to do that should not be enabled. thanks, greg k-h