From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S938663AbcHJURD (ORCPT ); Wed, 10 Aug 2016 16:17:03 -0400 Received: from mail-wm0-f68.google.com ([74.125.82.68]:35177 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933082AbcHJS1B (ORCPT ); Wed, 10 Aug 2016 14:27:01 -0400 Date: Wed, 10 Aug 2016 18:44:42 +0900 From: Sergey Senozhatsky To: js1304@gmail.com Cc: Andrew Morton , Vlastimil Babka , Minchan Kim , Michal Hocko , Sergey Senozhatsky , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Joonsoo Kim Subject: Re: [PATCH 2/5] mm/debug_pagealloc: don't allocate page_ext if we don't use guard page Message-ID: <20160810094442.GA674@swordfish> References: <1470809784-11516-1-git-send-email-iamjoonsoo.kim@lge.com> <1470809784-11516-3-git-send-email-iamjoonsoo.kim@lge.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1470809784-11516-3-git-send-email-iamjoonsoo.kim@lge.com> User-Agent: Mutt/1.6.2 (2016-07-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (08/10/16 15:16), js1304@gmail.com wrote: > From: Joonsoo Kim > > What debug_pagealloc does is just mapping/unmapping page table. > Basically, it doesn't need additional memory space to memorize something. > But, with guard page feature, it requires additional memory to distinguish > if the page is for guard or not. Guard page is only used when > debug_guardpage_minorder is non-zero so this patch removes additional > memory allocation (page_ext) if debug_guardpage_minorder is zero. > > It saves memory if we just use debug_pagealloc and not guard page. > > Signed-off-by: Joonsoo Kim Reviewed-by: Sergey Senozhatsky -ss