linux-kernel - MIGRATE_RESERVE pages in show

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Date:	Wed, 28 May 2014 10:24:44 +0800
From:	"Wang, Yalin" <Yalin.Wang@...ymobile.com>
To:	"'akpm@...ux-foundation.org'" <akpm@...ux-foundation.org>,
	"'linux-mm@...ck.org'" <linux-mm@...ck.org>,
	"'linux-kernel@...r.kernel.org'" <linux-kernel@...r.kernel.org>,
	"'cody@...ux.vnet.ibm.com'" <cody@...ux.vnet.ibm.com>,
	"'linux-arch-owner@...r.kernel.org'" 
	<linux-arch-owner@...r.kernel.org>,
	'Will Deacon' <will.deacon@....com>,
	"'hannes@...xchg.org'" <hannes@...xchg.org>
Subject: MIGRATE_RESERVE  pages in show_mem function problems

Hi  

I find the show_mem function show page MIGRATE types result is not correct for
MIGRATE_RESERVE pages :

Normal: 1582*4kB (UEMC) 1317*8kB (UEMC) 1020*16kB (UEMC) 450*32kB (UEMC) 206*64kB (UEMC) 40*128kB (UM) 10*256kB (UM) 10*512kB (UM) 1*1024kB (M) 0*2048kB 0*4096kB = 74592kB

Some pages should be marked (R)  , while it is changed into MIGRATE_MOVEABLE or UNMOVEABLE in free_area list ,
It's not correct for debug .
I make a patch for this:

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 5dba293..6ef8ebe 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1198,7 +1198,8 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order,
                        list_add_tail(&page->lru, list);
                if (IS_ENABLED(CONFIG_CMA)) {
                        mt = get_pageblock_migratetype(page);
-                       if (!is_migrate_cma(mt) && !is_migrate_isolate(mt))
+                       if (!is_migrate_cma(mt) && !is_migrate_isolate(mt)
+                               && mt != MIGRATE_RESERVE)
                                mt = migratetype;
                }
                set_freepage_migratetype(page, mt);


seems work ok , I am curious is it a BUG ? or designed like this for some reason ?

Thanks 


<6>[  250.751554] lowmem_reserve[]: 0 0 0
<6>[  250.751606] Normal: 1582*4kB (UEMC) 1317*8kB (UEMC) 1020*16kB (UEMC) 450*32kB (UEMC) 206*64kB (UEMC) 40*128kB (UM) 10*256kB (UM) 10*512kB (UM) 1*1024kB (M) 0*2048kB 0*4096kB = 74592kB
<6>[  250.751848] HighMem: 167*4kB (UC) 3*8kB (U) 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 692kB
<6>[  250.752020] 62596 total pagecache pages
<6>[  250.752046] 0 pages in swap cache
<6>[  250.752074] Swap cache stats: add 0, delete 0, find 0/0




Sony Mobile Communications
Tel: My Number +18610323092
yalin.wang@...ymobile.com  
sonymobile.com



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