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=-6.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS 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 25F0EC2BA19 for ; Thu, 16 Apr 2020 02:38:41 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id BB451206F9 for ; Thu, 16 Apr 2020 02:38:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="jrHbU5WL" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BB451206F9 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 2F7DD8E0071; Wed, 15 Apr 2020 22:38:40 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 282D48E0001; Wed, 15 Apr 2020 22:38:40 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 14B908E0071; Wed, 15 Apr 2020 22:38:40 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0164.hostedemail.com [216.40.44.164]) by kanga.kvack.org (Postfix) with ESMTP id ECD5D8E0001 for ; Wed, 15 Apr 2020 22:38:39 -0400 (EDT) Received: from smtpin13.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id A1D7C181AEF00 for ; Thu, 16 Apr 2020 02:38:39 +0000 (UTC) X-FDA: 76712159958.13.food11_68af0960dd149 X-HE-Tag: food11_68af0960dd149 X-Filterd-Recvd-Size: 7178 Received: from mail-pg1-f195.google.com (mail-pg1-f195.google.com [209.85.215.195]) by imf21.hostedemail.com (Postfix) with ESMTP for ; Thu, 16 Apr 2020 02:38:39 +0000 (UTC) Received: by mail-pg1-f195.google.com with SMTP id t11so947901pgg.2 for ; Wed, 15 Apr 2020 19:38:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:subject:to:cc:references:in-reply-to:mime-version :message-id:content-transfer-encoding; bh=inF2oUQWOVUn1zSzuLcDRWp19ZrU3frGNXSsTZrmfdQ=; b=jrHbU5WLW/3NRzRL4tUP93CurNe3euf3u04ZSvHtx4DoKvg6BdTPCBmBNvMyBxrmZ7 TgU6cisZ6MbOW00sFnL3XXqhrZos/MnOzXaPFFHxANt1Lbnm9vbEaY/H69/eXJTkDffy ipYXWrWZ5P1cZa1xWZhnN8U2oyc9HkCyolyDPlTsvYS1NbDcLglMyXiC04gAJ3QohUCR jjhhKSZFl5DZdnIqOWAvjUvsN7l3N7G0oCbfxTH2p8/CtE0JdvlD3sOFTmXSKJceP4wx +WBjX7cQkyZuAZdZmSzBG05XUhJpmhNFkrmD+CwNHb8SpwSIZ1DZTATXqT/9abQkBz88 tb5w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:subject:to:cc:references:in-reply-to :mime-version:message-id:content-transfer-encoding; bh=inF2oUQWOVUn1zSzuLcDRWp19ZrU3frGNXSsTZrmfdQ=; b=KXhmj14j9v4jzcpjW7rRtUVBXNFbM148umKIsqqJMze0vwgILCYEDxK75Wiw6DbT91 b19CS2SrVFWsuP1flgoyUPg/ZqSWfkjv3xyTuq670Z8V+aLAiLA54qFxnpGf+u7su3ec MOkooR/ClxOBuk8A2f61mNn8FK5X3Aen2u1LgggDoay4HJZ6vfND/veGnNhxr6stFq3z fRE/iW0HRt1Bc0ViKo7nKPGlm8aJmohy0sg9dpuTGFCYjj/GrTIhmtB9QMXOuvbEZWSO TvxM8ca3M68WMDz4DNMWaFTnCNfXCL7lpfmqALn4EDUiYFkRauaaaKCoTiX8bJ8NgwMW +PLQ== X-Gm-Message-State: AGi0Pub9ui6k7DmGfFrkbaamMjVFMndFAVdAQ800TY9WQBQrhwMBlNbE 2K3joBr37aVqIsqb04xAhc0= X-Google-Smtp-Source: APiQypLiACMHB4H40lzo7TjDzMxKO4UkcSYRYlY6AuEcTVgyHDfawhLANelI41IO6oDhsCuzUrA+DA== X-Received: by 2002:a62:7811:: with SMTP id t17mr31223582pfc.268.1587004718236; Wed, 15 Apr 2020 19:38:38 -0700 (PDT) Received: from localhost ([203.18.28.220]) by smtp.gmail.com with ESMTPSA id 198sm15506729pfa.87.2020.04.15.19.38.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Apr 2020 19:38:37 -0700 (PDT) Date: Thu, 16 Apr 2020 12:38:00 +1000 From: Nicholas Piggin Subject: Re: [PATCH v2 4/4] mm/vmalloc: Hugepage vmalloc mappings To: Will Deacon Cc: Borislav Petkov , Catalin Marinas , "H. Peter Anvin" , linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, Ingo Molnar , Thomas Gleixner , x86@kernel.org References: <20200413125303.423864-1-npiggin@gmail.com> <20200413125303.423864-5-npiggin@gmail.com> <20200415104755.GD12621@willie-the-truck> In-Reply-To: <20200415104755.GD12621@willie-the-truck> MIME-Version: 1.0 Message-Id: <1587003993.x84ylh11b2.astroid@bobo.none> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable 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: Excerpts from Will Deacon's message of April 15, 2020 8:47 pm: > Hi Nick, >=20 > On Mon, Apr 13, 2020 at 10:53:03PM +1000, Nicholas Piggin wrote: >> For platforms that define HAVE_ARCH_HUGE_VMAP and support PMD vmap mappi= ngs, >> have vmalloc attempt to allocate PMD-sized pages first, before falling b= ack >> to small pages. Allocations which use something other than PAGE_KERNEL >> protections are not permitted to use huge pages yet, not all callers exp= ect >> this (e.g., module allocations vs strict module rwx). >>=20 >> This gives a 6x reduction in dTLB misses for a `git diff` (of linux), fr= om >> 45600 to 6500 and a 2.2% reduction in cycles on a 2-node POWER9. >=20 > I wonder if it's worth extending vmap() to handle higher order pages in > a similar way? That might be helpful for tracing PMUs such as Arm SPE, > where the CPU streams tracing data out to a virtually addressed buffer > (see rb_alloc_aux_page()). Yeah it becomes pretty trivial to do that with VM_HUGE_PAGES after this patch, I have something to do it but no callers ready yet, if you have an easy one we can add it. >> This can result in more internal fragmentation and memory overhead for a >> given allocation. It can also cause greater NUMA unbalance on hashdist >> allocations. >>=20 >> There may be other callers that expect small pages under vmalloc but use >> PAGE_KERNEL, I'm not sure if it's feasible to catch them all. An >> alternative would be a new function or flag which enables large mappings= , >> and use that in callers. >>=20 >> Signed-off-by: Nicholas Piggin >> --- >> include/linux/vmalloc.h | 2 + >> mm/vmalloc.c | 135 +++++++++++++++++++++++++++++----------- >> 2 files changed, 102 insertions(+), 35 deletions(-) >>=20 >> diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h >> index 291313a7e663..853b82eac192 100644 >> --- a/include/linux/vmalloc.h >> +++ b/include/linux/vmalloc.h >> @@ -24,6 +24,7 @@ struct notifier_block; /* in notifier.h */ >> #define VM_UNINITIALIZED 0x00000020 /* vm_struct is not fully initializ= ed */ >> #define VM_NO_GUARD 0x00000040 /* don't add guard page */ >> #define VM_KASAN 0x00000080 /* has allocated kasan shadow memory = */ >> +#define VM_HUGE_PAGES 0x00000100 /* may use huge pages */ >=20 > Please can you add a check for this in the arm64 change_memory_common() > code? Other architectures might need something similar, but we need to > forbid changing memory attributes for portions of the huge page. Yeah good idea, I can look about adding some more checks. >=20 > In general, I'm a bit wary of software table walkers tripping over this. > For example, I don't think apply_to_existing_page_range() can handle > huge mappings at all, but the one user (KASAN) only ever uses page mappin= gs > so it's ok there. Right, I have something to warn for apply to page range (and looking at adding support for bigger pages). It doesn't even have a test and warn at the moment which isn't good practice IMO so we should add one even without huge vmap. >=20 >> @@ -2325,9 +2356,11 @@ static struct vm_struct *__get_vm_area_node(unsig= ned long size, >> if (unlikely(!size)) >> return NULL; >> =20 >> - if (flags & VM_IOREMAP) >> - align =3D 1ul << clamp_t(int, get_count_order_long(size), >> - PAGE_SHIFT, IOREMAP_MAX_ORDER); >> + if (flags & VM_IOREMAP) { >> + align =3D max(align, >> + 1ul << clamp_t(int, get_count_order_long(size), >> + PAGE_SHIFT, IOREMAP_MAX_ORDER)); >> + } >=20 >=20 > I don't follow this part. Please could you explain why you're potentially > aligning above IOREMAP_MAX_ORDER? It doesn't seem to follow from the rest > of the patch. Trying to remember. If the caller asks for a particular alignment we=20 shouldn't reduce it. Should put it in another patch. Thanks, Nick