Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932643AbdDQHir (ORCPT ); Mon, 17 Apr 2017 03:38:47 -0400 Received: from LGEAMRELO12.lge.com ([156.147.23.52]:55053 "EHLO lgeamrelo12.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932413AbdDQHim (ORCPT ); Mon, 17 Apr 2017 03:38:42 -0400 X-Original-SENDERIP: 156.147.1.127 X-Original-MAILFROM: minchan@kernel.org X-Original-SENDERIP: 165.244.249.25 X-Original-MAILFROM: minchan@kernel.org X-Original-SENDERIP: 10.177.223.161 X-Original-MAILFROM: minchan@kernel.org Date: Mon, 17 Apr 2017 16:38:08 +0900 From: Minchan Kim To: CC: Andrew Morton , Rik van Riel , Johannes Weiner , , Laura Abbott , Marek Szyprowski , Michal Nazarewicz , "Aneesh Kumar K . V" , Vlastimil Babka , Russell King , Will Deacon , , , , Joonsoo Kim Subject: Re: [PATCH v7 1/7] mm/page_alloc: don't reserve ZONE_HIGHMEM for ZONE_MOVABLE request Message-ID: <20170417073808.GA21354@bbox> References: <1491880640-9944-1-git-send-email-iamjoonsoo.kim@lge.com> <1491880640-9944-2-git-send-email-iamjoonsoo.kim@lge.com> MIME-Version: 1.0 In-Reply-To: <1491880640-9944-2-git-send-email-iamjoonsoo.kim@lge.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-MIMETrack: Itemize by SMTP Server on LGEKRMHUB08/LGE/LG Group(Release 8.5.3FP6|November 21, 2013) at 2017/04/17 16:38:10, Serialize by Router on LGEKRMHUB08/LGE/LG Group(Release 8.5.3FP6|November 21, 2013) at 2017/04/17 16:38:10, Serialize complete at 2017/04/17 16:38:10 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3054 Lines: 85 Hi Joonsoo, On Tue, Apr 11, 2017 at 12:17:14PM +0900, js1304@gmail.com wrote: > From: Joonsoo Kim > > Freepage on ZONE_HIGHMEM doesn't work for kernel memory so it's not that > important to reserve. When ZONE_MOVABLE is used, this problem would > theorectically cause to decrease usable memory for GFP_HIGHUSER_MOVABLE > allocation request which is mainly used for page cache and anon page > allocation. So, fix it. > > And, defining sysctl_lowmem_reserve_ratio array by MAX_NR_ZONES - 1 size > makes code complex. For example, if there is highmem system, following > reserve ratio is activated for *NORMAL ZONE* which would be easyily > misleading people. > > #ifdef CONFIG_HIGHMEM > 32 > #endif > > This patch also fix this situation by defining sysctl_lowmem_reserve_ratio > array by MAX_NR_ZONES and place "#ifdef" to right place. > > Reviewed-by: Aneesh Kumar K.V > Acked-by: Vlastimil Babka > Signed-off-by: Joonsoo Kim > --- > include/linux/mmzone.h | 2 +- > mm/page_alloc.c | 11 ++++++----- > 2 files changed, 7 insertions(+), 6 deletions(-) > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index ebaccd4..96194bf 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -869,7 +869,7 @@ int min_free_kbytes_sysctl_handler(struct ctl_table *, int, > void __user *, size_t *, loff_t *); > int watermark_scale_factor_sysctl_handler(struct ctl_table *, int, > void __user *, size_t *, loff_t *); > -extern int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1]; > +extern int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES]; > int lowmem_reserve_ratio_sysctl_handler(struct ctl_table *, int, > void __user *, size_t *, loff_t *); > int percpu_pagelist_fraction_sysctl_handler(struct ctl_table *, int, > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 32b31d6..60ffa4e 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -203,17 +203,18 @@ static void __free_pages_ok(struct page *page, unsigned int order); > * TBD: should special case ZONE_DMA32 machines here - in those we normally > * don't need any ZONE_NORMAL reservation > */ > -int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1] = { > +int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES] = { > #ifdef CONFIG_ZONE_DMA > - 256, > + [ZONE_DMA] = 256, > #endif > #ifdef CONFIG_ZONE_DMA32 > - 256, > + [ZONE_DMA32] = 256, > #endif > + [ZONE_NORMAL] = 32, > #ifdef CONFIG_HIGHMEM > - 32, > + [ZONE_HIGHMEM] = INT_MAX, > #endif > - 32, > + [ZONE_MOVABLE] = INT_MAX, > }; We need to update lowmem_reserve_ratio in Documentation/sysctl/vm.txt. And to me, INT_MAX is rather awkward. # cat /proc/sys/vm/lowmem_reserve_ratio 256 256 32 2147483647 2147483647 What do you think about to use 0 or -1 as special meaning instead 2147483647? Anyway, it could be separate patch regardless of zone_cma so I hope Andrew to merge this patch regardless of other patches in this patchset. Thanks.