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 AE15BC433EF for ; Mon, 25 Apr 2022 15:56:14 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3368C6B0074; Mon, 25 Apr 2022 11:56:14 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2E5416B0075; Mon, 25 Apr 2022 11:56:14 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1D4F36B0078; Mon, 25 Apr 2022 11:56:14 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.27]) by kanga.kvack.org (Postfix) with ESMTP id 0D8C36B0074 for ; Mon, 25 Apr 2022 11:56:14 -0400 (EDT) Received: from smtpin05.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay13.hostedemail.com (Postfix) with ESMTP id E3983619C7 for ; Mon, 25 Apr 2022 15:56:13 +0000 (UTC) X-FDA: 79395853026.05.EF8D3CA Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf23.hostedemail.com (Postfix) with ESMTP id BC0A814003E for ; Mon, 25 Apr 2022 15:56:08 +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 dfw.source.kernel.org (Postfix) with ESMTPS id 3B91361278; Mon, 25 Apr 2022 15:56:12 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A0018C385A9; Mon, 25 Apr 2022 15:56:08 +0000 (UTC) Date: Mon, 25 Apr 2022 16:56:05 +0100 From: Catalin Marinas To: Peter Collingbourne Cc: Andrey Konovalov , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Andrew Morton , Linux ARM , Linux Memory Management List , Linux Kernel Mailing List , vbabka@suse.cz, penberg@kernel.org, roman.gushchin@linux.dev, iamjoonsoo.kim@lge.com, rientjes@google.com, Herbert Xu , Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , kasan-dev , Eric Biederman , Kees Cook Subject: Re: [PATCH v3] mm: make minimum slab alignment a runtime property Message-ID: References: <20220422201830.288018-1-pcc@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220422201830.288018-1-pcc@google.com> X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: BC0A814003E X-Stat-Signature: rc9n44ggeo5iys1nwqbqby1xzkozfogc Authentication-Results: imf23.hostedemail.com; dkim=none; dmarc=fail reason="SPF not aligned (relaxed), No valid DKIM" header.from=arm.com (policy=none); spf=pass (imf23.hostedemail.com: domain of cmarinas@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=cmarinas@kernel.org X-Rspam-User: X-HE-Tag: 1650902168-965992 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 Fri, Apr 22, 2022 at 01:18:30PM -0700, Peter Collingbourne wrote: > When CONFIG_KASAN_HW_TAGS is enabled we currently increase the minimum > slab alignment to 16. This happens even if MTE is not supported in > hardware or disabled via kasan=off, which creates an unnecessary > memory overhead in those cases. Eliminate this overhead by making > the minimum slab alignment a runtime property and only aligning to > 16 if KASAN is enabled at runtime. > > On a DragonBoard 845c (non-MTE hardware) with a kernel built with > CONFIG_KASAN_HW_TAGS, waiting for quiescence after a full Android > boot I see the following Slab measurements in /proc/meminfo (median > of 3 reboots): > > Before: 169020 kB > After: 167304 kB > > Link: https://linux-review.googlesource.com/id/I752e725179b43b144153f4b6f584ceb646473ead > Signed-off-by: Peter Collingbourne > Reviewed-by: Andrey Konovalov Reviewed-by: Catalin Marinas