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 95A4BC433EF for ; Tue, 12 Jul 2022 23:05:59 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 16B019400D9; Tue, 12 Jul 2022 19:05:59 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 11BE2940063; Tue, 12 Jul 2022 19:05:59 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id F24FD9400D9; Tue, 12 Jul 2022 19:05:58 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id E0D52940063 for ; Tue, 12 Jul 2022 19:05:58 -0400 (EDT) Received: from smtpin03.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id B6EA220A54 for ; Tue, 12 Jul 2022 23:05:58 +0000 (UTC) X-FDA: 79679982396.03.36C9B29 Received: from mail-pj1-f54.google.com (mail-pj1-f54.google.com [209.85.216.54]) by imf05.hostedemail.com (Postfix) with ESMTP id 52052100048 for ; Tue, 12 Jul 2022 23:05:58 +0000 (UTC) Received: by mail-pj1-f54.google.com with SMTP id 89-20020a17090a09e200b001ef7638e536so718682pjo.3 for ; Tue, 12 Jul 2022 16:05:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=xf3o/FVcDrWTjqM4SU9OE71B6I+xuW/GFj0iZmpmQbg=; b=Z6IZzY9s3jOmwMJHCnOHfcd/X/fC5gga+f0/GnThBBONKEbR0I2NH1Ty6iOIdsZmZK aNZ+3HOLhzAiz/Mid2qzpPjGI4JFUuI7nGA4w+vhGU8t1Ok9afcoe/Jc3y3eYW+ViOab rveEgyZkqCy1hZZW8DMIBAUqyENo2A5JOeC+C7DZWne1sV1Bng0215Kup44rqee7ljzP 3+jP61rUQdp8Ls05woP3XU1jDYEQHcMan6eZ/rjuZCWJI/jS6HIryjgTfUh27QyF+0Qr HwRYJrJFek+4g2OqMsbQb+YRG+J8VOZMzWxz6CtFgnDzWRb8c+R5L/pvuutOzNOqXTJT 5rDQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=xf3o/FVcDrWTjqM4SU9OE71B6I+xuW/GFj0iZmpmQbg=; b=mF9FO+QWIIOqXYyHuWhw+VdrwSJkHIQclLoyhDOGtugPZYbMGP7ux/fCxwrGXT/2AF 5Bk8zkUSDfOs5i9q3CO6Yazx4P/fXky29wghq+SqR479CpqYD6fWr2D7AnWTGWUTApNo H3CUuSF6xyThyuENWL9ENt/0i+FnAeBVy8A5l+ftgLBKgdYJv85r+iAyGnuqlYVqXKL2 D9qzgjUhwLCXIVzQdL2eeVV7JsbNPmgQeAwabVYvHRCNGOn2GJawCyNWdQZZ3Jppp60Q CuU83cJx818ReYIB/R+Z+eio1OPxFL0tX7jvyiDrEJfQhfElcn/KEGTbawHdO57QGkWs 7AMg== X-Gm-Message-State: AJIora+ybDgJudNFtAOZ//OLc5I9urHcGvWTqc6i/uVYOwvTnJFc3UvW VIxxizNv6mFHSHMSKudahJx1wQ== X-Google-Smtp-Source: AGRyM1vgSDMytGaDjecq2tqtXq4s3MkrfSl0jPwry11NPVDZdGzL7EkgDGCSpo3Mk+AMiarqH+bA+Q== X-Received: by 2002:a17:903:2cb:b0:14f:4fb6:2fb0 with SMTP id s11-20020a17090302cb00b0014f4fb62fb0mr555392plk.172.1657667157162; Tue, 12 Jul 2022 16:05:57 -0700 (PDT) Received: from google.com (123.65.230.35.bc.googleusercontent.com. [35.230.65.123]) by smtp.gmail.com with ESMTPSA id x4-20020a17090ad68400b001f069352d73sm121393pju.25.2022.07.12.16.05.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 12 Jul 2022 16:05:56 -0700 (PDT) Date: Tue, 12 Jul 2022 23:05:53 +0000 From: Sean Christopherson To: Yosry Ahmed Cc: Tejun Heo , Johannes Weiner , Zefan Li , Marc Zyngier , James Morse , Alexandru Elisei , Suzuki K Poulose , Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Andrew Morton , Michal Hocko , Roman Gushchin , Shakeel Butt , Oliver Upton , Huang@google.com, Shaoqin , Cgroups , Linux Kernel Mailing List , linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, Linux-MM Subject: Re: [PATCH v6 1/4] mm: add NR_SECONDARY_PAGETABLE to count secondary page table uses. Message-ID: References: <20220628220938.3657876-1-yosryahmed@google.com> <20220628220938.3657876-2-yosryahmed@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1657667158; a=rsa-sha256; cv=none; b=famEw7bwJEMYImcXbTBSyYEHS0/cOlxoOjBfi1je/hnuvRONzKfGtyMb2QI/FYPPcjJQZe jgCEMTYUUtfyR0u5KCc2NWiuLl5NrfuDg8dxeNNljXarDj88F0Jo1qnSa7+cYQwjWMQh47 p4ryXg0sVMWGi5GAkGRBZGeFoV5IjDc= ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=Z6IZzY9s; spf=pass (imf05.hostedemail.com: domain of seanjc@google.com designates 209.85.216.54 as permitted sender) smtp.mailfrom=seanjc@google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1657667158; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=xf3o/FVcDrWTjqM4SU9OE71B6I+xuW/GFj0iZmpmQbg=; b=dbQW7AqHPfhF6O3q1Rr4mkV1H1pfgQNedwDotZQmC4FfPKsPNPuGP3mkOsh4qi5I9AhYP6 Mpyh5wlSYNGDMElOVtY3rvl0IW91+zm68Ny1hlqxSHRgaREXLjRVd2UZdkUhx/g/wWaGwH YwH8QkmXBpUxFocRi3enfKLxefsyw48= X-Rspamd-Queue-Id: 52052100048 Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=Z6IZzY9s; spf=pass (imf05.hostedemail.com: domain of seanjc@google.com designates 209.85.216.54 as permitted sender) smtp.mailfrom=seanjc@google.com; dmarc=pass (policy=reject) header.from=google.com X-Rspamd-Server: rspam02 X-Rspam-User: X-Stat-Signature: 117nxfu3sj1nyz78i65n7tf7q6wi6cj6 X-HE-Tag: 1657667158-582648 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 Tue, Jul 12, 2022, Yosry Ahmed wrote: > Thanks for taking another look at this! > > On Thu, Jul 7, 2022 at 1:59 PM Sean Christopherson wrote: > > > > On Tue, Jun 28, 2022, Yosry Ahmed wrote: > > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > > > index aab70355d64f3..13190d298c986 100644 > > > --- a/include/linux/mmzone.h > > > +++ b/include/linux/mmzone.h > > > @@ -216,6 +216,7 @@ enum node_stat_item { > > > NR_KERNEL_SCS_KB, /* measured in KiB */ > > > #endif > > > NR_PAGETABLE, /* used for pagetables */ > > > + NR_SECONDARY_PAGETABLE, /* secondary pagetables, e.g. kvm shadow pagetables */ > > > > Nit, s/kvm/KVM, and drop the "shadow", which might be misinterpreted as saying KVM > > pagetables are only accounted when KVM is using shadow paging. KVM's usage of "shadow" > > is messy, so I totally understand why you included it, but in this case it's unnecessary > > and potentially confusing. > > > > And finally, something that's not a nit. Should this be wrapped with CONFIG_KVM > > (using IS_ENABLED() because KVM can be built as a module)? That could be removed > > if another non-KVM secondary MMU user comes along, but until then, #ifdeffery for > > stats the depend on a single feature seems to be the status quo for this code. > > > > I will #ifdef the stat, but I will emphasize in the docs that is > currently *only* used for KVM so that it makes sense if users without > KVM don't see the stat at all. I will also remove the stat from > show_free_areas() in mm/page_alloc.c as it seems like none of the > #ifdefed stats show up there. It's might be worth getting someone from mm/ to weigh in before going through the trouble, my suggestion/question is based purely on the existing code.