From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sean Christopherson Subject: Re: [PATCH v6 1/4] mm: add NR_SECONDARY_PAGETABLE to count secondary page table uses. Date: Thu, 7 Jul 2022 20:59:41 +0000 Message-ID: References: <20220628220938.3657876-1-yosryahmed@google.com> <20220628220938.3657876-2-yosryahmed@google.com> Mime-Version: 1.0 Return-path: 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=A5MhBcXf8LVQ9gbV4fE8wcZW4gjzBdDH9411SgBm9nA=; b=JZQC6m6xR5sT0Jada7pN2ctPDZoVBgPNmsmVFV9xaOD0K1VcjdaDGI+Dbb9m6z+j0M HQZao2MwdnxdUCyFyWlgXqE0vhn5k0x3cFJEqeUSkVEsaLaami6rP5dYbVbdIFtecFK0 bszrtlQ/BBq6HtrtoG8nU1E+PvhE0lLr6U7Movo+h1ZN1VwhTvdz1ZHCpBxehT1XrGLp ldw665ro4GytFHnalr0o9hUTUOKVZe4kPdeCD4oNOEE/cifAyBR7BH7HyjVvjpbMGLv/ wuBFBMUf1JFMK20mDchKuifuX9NzhPRD+zMlfMD3Uo00M9pihW0RWuo1fPBLXJlg8Qnc EHBQ== Content-Disposition: inline In-Reply-To: <20220628220938.3657876-2-yosryahmed@google.com> List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infr On Tue, Jun 28, 2022, Yosry Ahmed wrote: > We keep track of several kernel memory stats (total kernel memory, page > tables, stack, vmalloc, etc) on multiple levels (global, per-node, > per-memcg, etc). These stats give insights to users to how much memory > is used by the kernel and for what purposes. > > Currently, memory used by kvm mmu is not accounted in any of those Nit, capitalize KVM (mainly to be consistent). > @@ -1085,6 +1086,9 @@ KernelStack > Memory consumed by the kernel stacks of all tasks > PageTables > Memory consumed by userspace page tables > +SecPageTables > + Memory consumed by secondary page tables, this currently > + currently includes KVM mmu allocations on x86 and arm64. Nit, this line has a tab instead of eight spaces. Not sure if it actually matters, there are plenty of tabs elsewhere in the file, but all the entries in this block use only spaces. > 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. > #ifdef CONFIG_SWAP > NR_SWAPCACHE, > #endif