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 X-Spam-Level: X-Spam-Status: No, score=-15.9 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2AFE6C56201 for ; Thu, 12 Nov 2020 01:35:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D04632076E for ; Thu, 12 Nov 2020 01:35:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="A/0yIMdi" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728947AbgKLBf5 (ORCPT ); Wed, 11 Nov 2020 20:35:57 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32870 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727912AbgKKX1V (ORCPT ); Wed, 11 Nov 2020 18:27:21 -0500 Received: from mail-wr1-x442.google.com (mail-wr1-x442.google.com [IPv6:2a00:1450:4864:20::442]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 32E5EC0613D1 for ; Wed, 11 Nov 2020 15:27:21 -0800 (PST) Received: by mail-wr1-x442.google.com with SMTP id k2so4169504wrx.2 for ; Wed, 11 Nov 2020 15:27:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to :user-agent; bh=WFixHAIkrgBx9SA97GwMYqSCYai8tNFPN/kssmEk0o0=; b=A/0yIMdiNF8p93t02fcd4+t9Grr2gNxUpyKTbL1FB8LsS8bGALDkBNJcBvtKaA5yOG Zd6UuuPqMX0BWJJ4+PQOHgfOAqkL81HJWHCXWWWGEUkSHARoZq5hpW3qMorjA0kGVhk2 bWiyNPORqejVX+FQd76EZblljwTmq9WaLMMorN/PkGMyl4TCCSNwxA+MeOw+Oq4BZyrU zsk74XvCoLTUHukaVgES3BpVCsaqpQRrkzY/6XQwV/10Yg9aJAlwKs7XtrxfkFSgQa58 nWYExiygmnqwhf4MKbDfhSAmEEQhcHTk6MXT7f9PWXpeBM/orvfuC1wSIjBxKuGx1TzV /pJg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to:user-agent; bh=WFixHAIkrgBx9SA97GwMYqSCYai8tNFPN/kssmEk0o0=; b=i4UAIGfLG/gfOlNVxyp3ZcdDqZilWt5jieX+n7D3xrcYX/8t+ofngQa1DkkqLQrD/v e3IH4mokIOWXVnEXi8fJL+piuPjbVktJgRcgPHES1WzY151z7LOcmK49QvbUsyRVyqQ0 1wnhudhdrPffwP4z98L1H3g2jlWuAeBwIHCG1i4GiKwzI9DVmdr5UNgCSkZbYs/Mqm54 mMrosao23wTR6oHiNF9TyF+xqaXlL0iMqn8bWf5y3rn4v/MoNa1NrOZqWnUe1+5Sk0b/ cIj3/OrD7B4n2XyhYXw11zq5gqg+GIHew2idMAV5+tXg6nXV2oazRRz+BdUt4JIJoOL0 yMJw== X-Gm-Message-State: AOAM532c+z5WUJGtcU3EnkHiX0yKxIhS4X28jcTLHLc2qxoF0tejmOk3 TNCgINQPusHAO25ZinoiI7X10w== X-Google-Smtp-Source: ABdhPJw6ksV/O2t8hl1ZAOb71lGfaA2WesPVswzx3IZTWdGrdDHO3revgaUrYCtvpuo6ZzKmqov2ow== X-Received: by 2002:adf:ce87:: with SMTP id r7mr1269889wrn.212.1605137239653; Wed, 11 Nov 2020 15:27:19 -0800 (PST) Received: from elver.google.com ([2a00:79e0:15:13:f693:9fff:fef4:2449]) by smtp.gmail.com with ESMTPSA id n123sm4187814wmn.38.2020.11.11.15.27.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Nov 2020 15:27:18 -0800 (PST) Date: Thu, 12 Nov 2020 00:27:13 +0100 From: Marco Elver To: Andrey Konovalov Cc: Dmitry Vyukov , Alexander Potapenko , Catalin Marinas , Will Deacon , Vincenzo Frascino , Evgenii Stepanov , Andrey Ryabinin , Branislav Rankov , Kevin Brodsky , Andrew Morton , kasan-dev@googlegroups.com, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 19/20] kasan, mm: allow cache merging with no metadata Message-ID: <20201111232713.GA1244863@elver.google.com> References: <936c0c198145b663e031527c49a6895bd21ac3a0.1605046662.git.andreyknvl@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <936c0c198145b663e031527c49a6895bd21ac3a0.1605046662.git.andreyknvl@google.com> User-Agent: Mutt/1.14.6 (2020-07-11) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 10, 2020 at 11:20PM +0100, Andrey Konovalov wrote: > The reason cache merging is disabled with KASAN is because KASAN puts its > metadata right after the allocated object. When the merged caches have > slightly different sizes, the metadata ends up in different places, which > KASAN doesn't support. > > It might be possible to adjust the metadata allocation algorithm and make > it friendly to the cache merging code. Instead this change takes a simpler > approach and allows merging caches when no metadata is present. Which is > the case for hardware tag-based KASAN with kasan.mode=prod. > > Signed-off-by: Andrey Konovalov > Link: https://linux-review.googlesource.com/id/Ia114847dfb2244f297d2cb82d592bf6a07455dba > --- > include/linux/kasan.h | 26 ++++++++++++++++++++++++-- > mm/kasan/common.c | 11 +++++++++++ > mm/slab_common.c | 11 ++++++++--- > 3 files changed, 43 insertions(+), 5 deletions(-) > [...] > > +/* > + * Only allow cache merging when stack collection is disabled and no metadata > + * is present. > + */ > +slab_flags_t __kasan_never_merge(slab_flags_t flags) I'm getting mm/kasan/common.c:88:14: warning: no previous prototype for ‘__kasan_never_merge’ [-Wmissing-prototypes] for a KASAN x86 build with W=1. Presumably because if !KASAN_HW_TAGS then this is never needed and defined static inline in the header. > +{ > + if (kasan_stack_collection_enabled()) > + return flags; > + return flags & ~SLAB_KASAN; > +} Thanks, -- Marco