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X-IronPort-AV: E=McAfee;i="6600,9927,10838"; a="410908988" X-IronPort-AV: E=Sophos;i="6.02,160,1688454000"; d="scan'208";a="410908988" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Sep 2023 09:02:09 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10838"; a="746294853" X-IronPort-AV: E=Sophos;i="6.02,160,1688454000"; d="scan'208";a="746294853" Received: from rdromms-mobl4.amr.corp.intel.com (HELO [10.212.158.204]) ([10.212.158.204]) by orsmga002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Sep 2023 09:02:08 -0700 Message-ID: <782b131a-c3b9-7679-824a-70625c966def@intel.com> Date: Tue, 19 Sep 2023 09:02:07 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 Subject: Re: [RFC PATCH 00/14] Prevent cross-cache attacks in the SLUB allocator Content-Language: en-US To: Matteo Rizzo , Linus Torvalds Cc: Ingo Molnar , "Lameter, Christopher" , penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, vbabka@suse.cz, roman.gushchin@linux.dev, 42.hyeyoo@gmail.com, keescook@chromium.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-hardening@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, corbet@lwn.net, luto@kernel.org, peterz@infradead.org, jannh@google.com, evn@google.com, poprdi@google.com, jordyzomer@google.com References: <20230915105933.495735-1-matteorizzo@google.com> <7a4f5128-28fd-3c5f-34c2-1c34f4448174@intel.com> <1d7573c0-ebbc-6ed2-f152-1045eb0542f9@os.amperecomputing.com> From: Dave Hansen In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: EA5144002C X-Rspam-User: X-Stat-Signature: hotjt9y1abefnmxpephwyz6uhxjtjyrh X-Rspamd-Server: rspam01 X-HE-Tag: 1695139576-36833 X-HE-Meta: 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 vct233ah BKXVzyTOC0XwfmwQf71tuEAG7zEhGIiktHqtZPA7Y6OSEe1HNKdYZBF01UJDbsF2S5D+6RW+b2pzXTKGcH8EepSO7BNiYyryA8VIIxLEsr9K/yYLxkIgeGHZHTkrGa4NEbvgcIscgprbOwKWKKRYItk0C+bmlaDYUPHyYrdtWZvtBl0yhq2WatAeq8sL12Zq/58yFCpGaV/vXcMf8kjnmypIYxg== 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 9/19/23 08:48, Matteo Rizzo wrote: >> I think the whole "make it one single compile-time option" model is >> completely and fundamentally broken. > Wouldn't making this toggleable at boot time or runtime make performance > even worse? Maybe. But you can tolerate even more of a performance impact from a feature if the people that don't care can actually disable it. There are also plenty of ways to minimize the overhead of switching it on and off at runtime. Static branches are your best friend here.