From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f199.google.com (mail-io0-f199.google.com [209.85.223.199]) by kanga.kvack.org (Postfix) with ESMTP id 4A4D66B0253 for ; Tue, 28 Jun 2016 07:24:21 -0400 (EDT) Received: by mail-io0-f199.google.com with SMTP id g13so28686632ioj.3 for ; Tue, 28 Jun 2016 04:24:21 -0700 (PDT) Received: from szxga03-in.huawei.com (szxga03-in.huawei.com. [119.145.14.66]) by mx.google.com with ESMTPS id z126si34342ioe.242.2016.06.28.04.24.19 for (version=TLS1 cipher=AES128-SHA bits=128/128); Tue, 28 Jun 2016 04:24:20 -0700 (PDT) Subject: Re: [PATCH v3 3/6] mm/cma: populate ZONE_CMA References: <1464243748-16367-1-git-send-email-iamjoonsoo.kim@lge.com> <1464243748-16367-4-git-send-email-iamjoonsoo.kim@lge.com> <576A58FA.8040101@hisilicon.com> <20160623025238.GB30438@js1304-P5Q-DELUXE> From: Chen Feng Message-ID: <57725E2B.3000201@hisilicon.com> Date: Tue, 28 Jun 2016 19:23:23 +0800 MIME-Version: 1.0 In-Reply-To: <20160623025238.GB30438@js1304-P5Q-DELUXE> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Joonsoo Kim Cc: Andrew Morton , Rik van Riel , Johannes Weiner , mgorman@techsingularity.net, Laura Abbott , Minchan Kim , Marek Szyprowski , Michal Nazarewicz , "Aneesh Kumar K.V" , Vlastimil Babka , Rui Teng , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "fujun (F)" , Zhuangluan Su , Yiping Xu , Dan Zhao Hello, On 2016/6/23 10:52, Joonsoo Kim wrote: > On Wed, Jun 22, 2016 at 05:23:06PM +0800, Chen Feng wrote: >> Hello, >> >> On 2016/5/26 14:22, js1304@gmail.com wrote: >>> From: Joonsoo Kim >>> >>> Until now, reserved pages for CMA are managed in the ordinary zones >>> where page's pfn are belong to. This approach has numorous problems >>> and fixing them isn't easy. (It is mentioned on previous patch.) >>> To fix this situation, ZONE_CMA is introduced in previous patch, but, >>> not yet populated. This patch implement population of ZONE_CMA >>> by stealing reserved pages from the ordinary zones. >>> >>> Unlike previous implementation that kernel allocation request with >>> __GFP_MOVABLE could be serviced from CMA region, allocation request only >>> with GFP_HIGHUSER_MOVABLE can be serviced from CMA region in the new >>> approach. This is an inevitable design decision to use the zone >>> implementation because ZONE_CMA could contain highmem. Due to this >>> decision, ZONE_CMA will work like as ZONE_HIGHMEM or ZONE_MOVABLE. >>> >>> I don't think it would be a problem because most of file cache pages >>> and anonymous pages are requested with GFP_HIGHUSER_MOVABLE. It could >>> be proved by the fact that there are many systems with ZONE_HIGHMEM and >>> they work fine. Notable disadvantage is that we cannot use these pages >>> for blockdev file cache page, because it usually has __GFP_MOVABLE but >>> not __GFP_HIGHMEM and __GFP_USER. But, in this case, there is pros and >>> cons. In my experience, blockdev file cache pages are one of the top >>> reason that causes cma_alloc() to fail temporarily. So, we can get more >>> guarantee of cma_alloc() success by discarding that case. >>> >>> Implementation itself is very easy to understand. Steal when cma area is >>> initialized and recalculate various per zone stat/threshold. >>> >>> Signed-off-by: Joonsoo Kim >>> --- >>> include/linux/memory_hotplug.h | 3 --- >>> mm/cma.c | 41 +++++++++++++++++++++++++++++++++++++++++ >>> mm/internal.h | 3 +++ >>> mm/page_alloc.c | 26 ++++++++++++++++++++++++-- >>> 4 files changed, 68 insertions(+), 5 deletions(-) >>> >>> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h >>> index a864d79..6fde69b 100644 >>> --- a/include/linux/memory_hotplug.h >>> +++ b/include/linux/memory_hotplug.h >>> @@ -198,9 +198,6 @@ void put_online_mems(void); >>> void mem_hotplug_begin(void); >>> void mem_hotplug_done(void); >>> >>> -extern void set_zone_contiguous(struct zone *zone); >>> -extern void clear_zone_contiguous(struct zone *zone); >>> - >>> #else /* ! CONFIG_MEMORY_HOTPLUG */ >>> /* >>> * Stub functions for when hotplug is off >>> diff --git a/mm/cma.c b/mm/cma.c >>> index ea506eb..8684f50 100644 >>> --- a/mm/cma.c >>> +++ b/mm/cma.c >>> @@ -38,6 +38,7 @@ >>> #include >>> >>> #include "cma.h" >>> +#include "internal.h" >>> >>> struct cma cma_areas[MAX_CMA_AREAS]; >>> unsigned cma_area_count; >>> @@ -145,6 +146,11 @@ err: >>> static int __init cma_init_reserved_areas(void) >>> { >>> int i; >>> + struct zone *zone; >>> + unsigned long start_pfn = UINT_MAX, end_pfn = 0; >>> + >>> + if (!cma_area_count) >>> + return 0; >>> >>> for (i = 0; i < cma_area_count; i++) { >>> int ret = cma_activate_area(&cma_areas[i]); >>> @@ -153,6 +159,41 @@ static int __init cma_init_reserved_areas(void) >>> return ret; >>> } >>> >>> + for (i = 0; i < cma_area_count; i++) { >>> + if (start_pfn > cma_areas[i].base_pfn) >>> + start_pfn = cma_areas[i].base_pfn; >>> + if (end_pfn < cma_areas[i].base_pfn + cma_areas[i].count) >>> + end_pfn = cma_areas[i].base_pfn + cma_areas[i].count; >>> + } >>> + >>> + for_each_populated_zone(zone) { >>> + if (!is_zone_cma(zone)) >>> + continue; >>> + >>> + /* ZONE_CMA doesn't need to exceed CMA region */ >>> + zone->zone_start_pfn = max(zone->zone_start_pfn, start_pfn); >>> + zone->spanned_pages = min(zone_end_pfn(zone), end_pfn) - >>> + zone->zone_start_pfn; >>> + } >>> + >>> + /* >>> + * Reserved pages for ZONE_CMA are now activated and this would change >>> + * ZONE_CMA's managed page counter and other zone's present counter. >>> + * We need to re-calculate various zone information that depends on >>> + * this initialization. >>> + */ >>> + build_all_zonelists(NULL, NULL); >>> + for_each_populated_zone(zone) { >>> + zone_pcp_update(zone); >>> + set_zone_contiguous(zone); >>> + } >>> + >>> + /* >>> + * We need to re-init per zone wmark by calling >>> + * init_per_zone_wmark_min() but doesn't call here because it is >>> + * registered on module_init and it will be called later than us. >>> + */ >>> + >>> return 0; >>> } >>> core_initcall(cma_init_reserved_areas); >>> diff --git a/mm/internal.h b/mm/internal.h >>> index b6ead95..4c37234 100644 >>> --- a/mm/internal.h >>> +++ b/mm/internal.h >>> @@ -155,6 +155,9 @@ extern void __free_pages_bootmem(struct page *page, unsigned long pfn, >>> extern void prep_compound_page(struct page *page, unsigned int order); >>> extern int user_min_free_kbytes; >>> >>> +extern void set_zone_contiguous(struct zone *zone); >>> +extern void clear_zone_contiguous(struct zone *zone); >>> + >>> #if defined CONFIG_COMPACTION || defined CONFIG_CMA >>> >>> /* >>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >>> index 0197d5d..796b271 100644 >>> --- a/mm/page_alloc.c >>> +++ b/mm/page_alloc.c >>> @@ -1572,16 +1572,38 @@ void __init page_alloc_init_late(void) >>> } >>> >>> #ifdef CONFIG_CMA >>> +static void __init adjust_present_page_count(struct page *page, long count) >>> +{ >>> + struct zone *zone = page_zone(page); >>> + >>> + /* We don't need to hold a lock since it is boot-up process */ >>> + zone->present_pages += count; >>> +} >>> + >>> /* Free whole pageblock and set its migration type to MIGRATE_CMA. */ >>> void __init init_cma_reserved_pageblock(struct page *page) >>> { >>> unsigned i = pageblock_nr_pages; >>> + unsigned long pfn = page_to_pfn(page); >>> struct page *p = page; >>> + int nid = page_to_nid(page); >>> + >>> + /* >>> + * ZONE_CMA will steal present pages from other zones by changing >>> + * page links so page_zone() is changed. Before that, >>> + * we need to adjust previous zone's page count first. >>> + */ >>> + adjust_present_page_count(page, -pageblock_nr_pages); >>> >>> do { >>> __ClearPageReserved(p); >>> set_page_count(p, 0); >>> - } while (++p, --i); >>> + >>> + /* Steal pages from other zones */ >>> + set_page_links(p, ZONE_CMA, nid, pfn); >>> + } while (++p, ++pfn, --i); >>> + >>> + adjust_present_page_count(page, pageblock_nr_pages); >>> >>> set_pageblock_migratetype(page, MIGRATE_CMA); >> >> The ZONE_CMA should depends on sparse_mem. >> >> Because the zone size is not fixed when init the buddy core. >> The pageblock_flags will be NULL when setup_usemap. > > Before setup_usemap(), range of ZONE_CMA is set conservatively, from > min_start_pfn of the node to max_end_pfn of the node. So, > pageblock_flags will be allocated and assigned properly. > > Unfortunately, I found a bug for FLATMEM system. If you'd like to > test ZONE_CMA on FLATMEM system, please apply below one. > The filesystem, inode map is also GFP_HIGHUSER_MOVABLE. SyS_write filemap_fault will also use cma memory. This may also make cma migrate failed. What's your idea on this type? > Thanks. > ------------>8------------ > diff --git a/mm/cma.c b/mm/cma.c > index 0c1a72f..6cd2973 100644 > --- a/mm/cma.c > +++ b/mm/cma.c > @@ -168,13 +168,6 @@ static int __init cma_init_reserved_areas(void) > return 0; > > for (i = 0; i < cma_area_count; i++) { > - int ret = cma_activate_area(&cma_areas[i]); > - > - if (ret) > - return ret; > - } > - > - for (i = 0; i < cma_area_count; i++) { > if (start_pfn > cma_areas[i].base_pfn) > start_pfn = cma_areas[i].base_pfn; > if (end_pfn < cma_areas[i].base_pfn + cma_areas[i].count) > @@ -191,6 +184,13 @@ static int __init cma_init_reserved_areas(void) > zone->zone_start_pfn; > } > > + for (i = 0; i < cma_area_count; i++) { > + int ret = cma_activate_area(&cma_areas[i]); > + > + if (ret) > + return ret; > + } > + > /* > * Reserved pages for ZONE_CMA are now activated and this would change > * ZONE_CMA's managed page counter and other zone's present counter. > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org