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To: Sean Christopherson 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 Content-Type: text/plain; charset="UTF-8" ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=gld9078C; spf=pass (imf16.hostedemail.com: domain of yosryahmed@google.com designates 209.85.221.45 as permitted sender) smtp.mailfrom=yosryahmed@google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1659989215; a=rsa-sha256; cv=none; b=yTzC7Jpzv69JSeLIDgFy7xbMtRHGckG3yvrcwIDMucL/f5pvq0oqYDN5WkNPPedAvwOUkj J3TmYIWf99cVmjRLbrDvtDbvYRH7B7Z/5BiSS/90uOcwAtiVXMrt6zC2e/Ha0iQ10W3Dbv DYHPduMHZaa9tbRTs7M1e+IRCTp0SIc= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1659989215; 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=0j4dwLC8wxMrSAowWiy7rSpW5tCFJnoA4YLc0AuNUGg=; b=tFq4TLK+ua99e/FpinIf4QzlZS5OFys5+pLM9hvVTfrG9RmTlZzvHOfyJtXwHewy7UXjGL 4A8ELLsNMKt9A0fgFluVjRT221JJAOzeHFJkjfCgG1NxQbQkC0vwyBlfPHRA9nBmZ5xJj4 Y5tyuPR2xfImS4sh1m3dlPNl/wYDN+c= X-Stat-Signature: 9sn5axyjzksztdgoydocxn16frrxgfkq X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 017DA180162 Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=gld9078C; spf=pass (imf16.hostedemail.com: domain of yosryahmed@google.com designates 209.85.221.45 as permitted sender) smtp.mailfrom=yosryahmed@google.com; dmarc=pass (policy=reject) header.from=google.com X-HE-Tag: 1659989214-98900 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 Mon, Jul 18, 2022 at 11:26 AM Yosry Ahmed wrote: > > On Tue, Jul 12, 2022 at 4:06 PM Sean Christopherson wrote: > > > > 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. > > Any mm folks with an opinion about this? > > Any preference on whether we should wrap NR_SECONDARY_PAGETABLE stats > with #ifdef CONFIG_KVM for now as it is currently the only source for > this stat? Any input here? Johannes, you have been involved in discussions in earlier versions of this series, any thoughts here?