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 E106EC433EF for ; Fri, 22 Apr 2022 16:09:17 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 532CE8D0002; Fri, 22 Apr 2022 12:09:17 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4E2576B00AA; Fri, 22 Apr 2022 12:09:17 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 383B48D0002; Fri, 22 Apr 2022 12:09:17 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.25]) by kanga.kvack.org (Postfix) with ESMTP id 28BC66B00A9 for ; Fri, 22 Apr 2022 12:09:17 -0400 (EDT) Received: from smtpin09.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay12.hostedemail.com (Postfix) with ESMTP id EB64C120754 for ; Fri, 22 Apr 2022 16:09:16 +0000 (UTC) X-FDA: 79384999512.09.0A324F2 Received: from mail-io1-f53.google.com (mail-io1-f53.google.com [209.85.166.53]) by imf11.hostedemail.com (Postfix) with ESMTP id 6E0894002F for ; Fri, 22 Apr 2022 16:09:14 +0000 (UTC) Received: by mail-io1-f53.google.com with SMTP id r12so9073036iod.6 for ; Fri, 22 Apr 2022 09:09:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=7ywngeaPOxck8z+da0Rb5cHl7IWBnc+HuyghQxZLcVk=; b=oG1haJS5hmczkwWbyWqWbIQaUylnKJJUnzf14PdQs7QjktBBhU9YQSVIFpfGm8F1RJ A3p1lsqVP5QDbT7NEnVUml3TwvhnPfRRU+pq8FwWMksiYbc7BXjHZQhVLz71LSIKH7DF xeDLcInX5J6paNdMWEqpbYQg/JX/BdrznAnRH4TB20PgkpDWy3N5AaxLehVf/qY/Qxa/ 1GI5+1Eq6ZsSznd6mrEWnsgZGHzos/iR+voO3zTbfBArFy9D0r9uhbe6x/YeYFS6qk2+ FY0QedT2lpEcnbhin5BCJMx3i/ot7yBiZbNx5G1qvaD7V3m+CMqlhRCwjoh8hIVuoYRn NJTg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=7ywngeaPOxck8z+da0Rb5cHl7IWBnc+HuyghQxZLcVk=; b=EpykX/ADj5PlAgO0CUIBSoWOKiiUtJnKgFnlKp+32Vd/PDHkvEUEi+gLPNSVW2dXBW 7OEdClFG+tMLXV3lejIZCbg4TxHJp27qj+mhkwqqe8WqqjOR7KWsMfruaxwdlSqesfXc vpQsdLGL3mUhPJjlAdy66jzR6MqmjRXdpjB2kx0qgSxnXQBk/07KL7xvqSYO9Uz/GYiW JJL8OZ+Vwp9umdgxaFjPMUgbBTd5RiyYitcTjBGaHY3UnOM6Nhb6pWEqJH2aofjYWeXu xwSfeN+EMwEIjWZnmhBrmeo9NCRaC2l4lP7JJ/k4PWV26hidkFLNCFnrDjcwcUF68+Ma wVSg== X-Gm-Message-State: AOAM532ZseZkSPo0OPBkHoyL77ulu/hZKcv+MxqbSf+U/ZGVRQMT/7yp xjNppY3UTYrksucpxJVfeySu97QujnQv8iJRuIM= X-Google-Smtp-Source: ABdhPJytqgoKB/LhjwjdWDKbDXz5rBm+JEhsXjBZkk1xtyNUNvug+BnxZy8qyRlmSnBYP4X43IatfCoxx82hSJwBO+E= X-Received: by 2002:a05:6638:dd3:b0:32a:7bdd:799b with SMTP id m19-20020a0566380dd300b0032a7bdd799bmr2474463jaj.117.1650643755556; Fri, 22 Apr 2022 09:09:15 -0700 (PDT) MIME-Version: 1.0 References: <20220421031738.3168157-1-pcc@google.com> In-Reply-To: From: Andrey Konovalov Date: Fri, 22 Apr 2022 18:09:04 +0200 Message-ID: Subject: Re: [PATCH] mm: make minimum slab alignment a runtime property To: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Peter Collingbourne , Andrew Morton , Linux ARM , Linux Memory Management List , Linux Kernel Mailing List , Vlastimil Babka , Pekka Enberg , cl@linux.org, roman.gushchin@linux.dev, Joonsoo Kim , David Rientjes , Catalin Marinas , Herbert Xu , Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , kasan-dev , Eric Biederman , Kees Cook Content-Type: text/plain; charset="UTF-8" X-Stat-Signature: uhw1mk9oisqzb7rqx1axaxpiogz7x4bn X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 6E0894002F Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=oG1haJS5; spf=pass (imf11.hostedemail.com: domain of andreyknvl@gmail.com designates 209.85.166.53 as permitted sender) smtp.mailfrom=andreyknvl@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-Rspam-User: X-HE-Tag: 1650643754-287354 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 2:39 PM Hyeonggon Yoo <42.hyeyoo@gmail.com> wrote: > > > > kasan_hw_tags_enabled() is also false when kasan is just not initialized yet. > > > What about writing a new helper something like kasan_is_disabled() > > > instead? > > > > The decision of whether to enable KASAN is made early, before the slab > > allocator is initialized (start_kernel -> smp_prepare_boot_cpu -> > > kasan_init_hw_tags vs start_kernel -> mm_init -> kmem_cache_init). If > > you think about it, this needs to be the case for KASAN to operate > > correctly because it influences the behavior of the slab allocator via > > the kasan_*poison* hooks. So I don't think we can end up calling this > > function before then. > > Sounds not bad. I wanted to make sure the value of arch_slab_minaligned() > is not changed during its execution. > > Just some part of me thought something like this would be more > intuitive/robust. > > if (systems_supports_mte() && kasan_arg != KASAN_ARG_OFF) > return MTE_GRANULE_SIZE; > else > return __alignof__(unsigned long long); Hi Hyeonggon, We could add and use kasan_hw_rags_requested(), which would return (systems_supports_mte() && kasan_arg != KASAN_ARG_OFF). However, I'm not sure we will get a fully static behavior: systems_supports_mte() also only starts returning proper result at some point during CPU bring-up if I'm not mistaken. Thanks!