From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1754522AbcFPRVs (ORCPT <rfc822;w@1wt.eu>);
	Thu, 16 Jun 2016 13:21:48 -0400
Received: from mail-oi0-f50.google.com ([209.85.218.50]:33937 "EHLO
	mail-oi0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1753942AbcFPRVr (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Thu, 16 Jun 2016 13:21:47 -0400
MIME-Version: 1.0
In-Reply-To: <20160616111053.GA13143@esperanza>
References: <cover.1466036668.git.luto@kernel.org> <24279d4009c821de64109055665429fad2a7bff7.1466036668.git.luto@kernel.org>
 <20160616111053.GA13143@esperanza>
From: Andy Lutomirski <luto@amacapital.net>
Date: Thu, 16 Jun 2016 10:21:26 -0700
Message-ID: <CALCETrU4bcLyBJDVOPCW_MobQVGPiHRP+KfZMGu8YQJHnmjYeQ@mail.gmail.com>
Subject: Re: [PATCH 04/13] mm: Track NR_KERNEL_STACK in pages instead of
 number of stacks
To: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Andy Lutomirski <luto@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        X86 ML <x86@kernel.org>, Borislav Petkov <bp@alien8.de>,
        Nadav Amit <nadav.amit@gmail.com>, Kees Cook <keescook@chromium.org>,
        Brian Gerst <brgerst@gmail.com>,
        "kernel-hardening@lists.openwall.com" 
	<kernel-hardening@lists.openwall.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Johannes Weiner <hannes@cmpxchg.org>, Michal Hocko <mhocko@kernel.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>
Content-Type: text/plain; charset=UTF-8
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Thu, Jun 16, 2016 at 4:10 AM, Vladimir Davydov
<vdavydov@virtuozzo.com> wrote:
> On Wed, Jun 15, 2016 at 05:28:26PM -0700, Andy Lutomirski wrote:
> ...
>> @@ -225,7 +225,8 @@ static void account_kernel_stack(struct thread_info *ti, int account)
>>  {
>>       struct zone *zone = page_zone(virt_to_page(ti));
>>
>> -     mod_zone_page_state(zone, NR_KERNEL_STACK, account);
>> +     mod_zone_page_state(zone, NR_KERNEL_STACK,
>> +                         THREAD_SIZE / PAGE_SIZE * account);
>
> It won't work if THREAD_SIZE < PAGE_SIZE. Is there an arch with such a
> thread size, anyway? If no, we should probably drop thread_info_cache.

On a quick grep, I can't find any.  I'll add a BUILD_BUG_ON for now.

--Andy