diff mbox

[v4,3/8] memory-hotplug: fix NR_FREE_PAGES mismatch

Message ID 1351682594-17347-4-git-send-email-wency@cn.fujitsu.com (mailing list archive)
State RFC, archived
Headers show

Commit Message

Wen Congyang Oct. 31, 2012, 11:23 a.m. UTC 
NR_FREE_PAGES will be wrong after offlining pages.  We add/dec
NR_FREE_PAGES like this now:

1. move all pages in buddy system to MIGRATE_ISOLATE, and dec NR_FREE_PAGES

2. don't add NR_FREE_PAGES when it is freed and the migratetype is
   MIGRATE_ISOLATE

3. dec NR_FREE_PAGES when offlining isolated pages.

4. add NR_FREE_PAGES when undoing isolate pages.

When we come to step 3, all pages are in MIGRATE_ISOLATE list, and
NR_FREE_PAGES are right.  When we come to step4, all pages are not in
buddy system, so we don't change NR_FREE_PAGES in this step, but we change
NR_FREE_PAGES in step3.  So NR_FREE_PAGES is wrong after offlining pages.
So there is no need to change NR_FREE_PAGES in step3.

This patch also fixs a problem in step2: if the migratetype is
MIGRATE_ISOLATE, we should not add NR_FRR_PAGES when we remove pages from
pcppages.

Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Jiang Liu <liuj97@gmail.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 mm/page_alloc.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

Comments

wujianguo Oct. 31, 2012, 1:41 p.m. UTC | #1 
On 2012/10/31 19:23, Wen Congyang wrote:
> NR_FREE_PAGES will be wrong after offlining pages.  We add/dec
> NR_FREE_PAGES like this now:
> 
> 1. move all pages in buddy system to MIGRATE_ISOLATE, and dec NR_FREE_PAGES
> 
> 2. don't add NR_FREE_PAGES when it is freed and the migratetype is
>    MIGRATE_ISOLATE
> 
> 3. dec NR_FREE_PAGES when offlining isolated pages.
> 
> 4. add NR_FREE_PAGES when undoing isolate pages.
> 
> When we come to step 3, all pages are in MIGRATE_ISOLATE list, and
> NR_FREE_PAGES are right.  When we come to step4, all pages are not in
> buddy system, so we don't change NR_FREE_PAGES in this step, but we change
> NR_FREE_PAGES in step3.  So NR_FREE_PAGES is wrong after offlining pages.
> So there is no need to change NR_FREE_PAGES in step3.
> 
> This patch also fixs a problem in step2: if the migratetype is
> MIGRATE_ISOLATE, we should not add NR_FRR_PAGES when we remove pages from
> pcppages.
> 
> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
> Cc: David Rientjes <rientjes@google.com>
> Cc: Jiang Liu <liuj97@gmail.com>
> Cc: Len Brown <len.brown@intel.com>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Christoph Lameter <cl@linux.com>
> Cc: Minchan Kim <minchan.kim@gmail.com>
> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
> Cc: Dave Hansen <dave@linux.vnet.ibm.com>
> Cc: Mel Gorman <mel@csn.ul.ie>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---
>  mm/page_alloc.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 5b74de6..a7cd2d1 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -667,11 +667,13 @@ static void free_pcppages_bulk(struct zone *zone, int count,
>  			/* MIGRATE_MOVABLE list may include MIGRATE_RESERVEs */
>  			__free_one_page(page, zone, 0, mt);
>  			trace_mm_page_pcpu_drain(page, 0, mt);
> -			if (is_migrate_cma(mt))
> -				__mod_zone_page_state(zone, NR_FREE_CMA_PAGES, 1);
> +			if (likely(mt != MIGRATE_ISOLATE)) {

Hi Congyang,
	I think mt != MIGRATE_ISOLATE is always true here,
page from PCP's migratetype < MIGRATE_PCPTYPES.
When isolate page, we change pageblock's migratetype to MIGRATE_ISOLATE,
but set_freepage_migratetype() isn't called.
Maybe we can use mt = get_pageblock_migratetype() here ?

Thanks,
Jianguo Wu.

> +				__mod_zone_page_state(zone, NR_FREE_PAGES, 1);
> +				if (is_migrate_cma(mt))
> +					__mod_zone_page_state(zone, NR_FREE_CMA_PAGES, 1);
> +			}
>  		} while (--to_free && --batch_free && !list_empty(list));
>  	}
> -	__mod_zone_page_state(zone, NR_FREE_PAGES, count);
>  	spin_unlock(&zone->lock);
>  }
>  
> @@ -5987,8 +5989,6 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
>  		list_del(&page->lru);
>  		rmv_page_order(page);
>  		zone->free_area[order].nr_free--;
> -		__mod_zone_page_state(zone, NR_FREE_PAGES,
> -				      - (1UL << order));
>  		for (i = 0; i < (1 << order); i++)
>  			SetPageReserved((page+i));
>  		pfn += (1 << order);
> 

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Wen Congyang Nov. 1, 2012, 3 a.m. UTC | #2 
At 10/31/2012 09:41 PM, Jianguo Wu Wrote:
> On 2012/10/31 19:23, Wen Congyang wrote:
>> NR_FREE_PAGES will be wrong after offlining pages.  We add/dec
>> NR_FREE_PAGES like this now:
>>
>> 1. move all pages in buddy system to MIGRATE_ISOLATE, and dec NR_FREE_PAGES
>>
>> 2. don't add NR_FREE_PAGES when it is freed and the migratetype is
>>    MIGRATE_ISOLATE
>>
>> 3. dec NR_FREE_PAGES when offlining isolated pages.
>>
>> 4. add NR_FREE_PAGES when undoing isolate pages.
>>
>> When we come to step 3, all pages are in MIGRATE_ISOLATE list, and
>> NR_FREE_PAGES are right.  When we come to step4, all pages are not in
>> buddy system, so we don't change NR_FREE_PAGES in this step, but we change
>> NR_FREE_PAGES in step3.  So NR_FREE_PAGES is wrong after offlining pages.
>> So there is no need to change NR_FREE_PAGES in step3.
>>
>> This patch also fixs a problem in step2: if the migratetype is
>> MIGRATE_ISOLATE, we should not add NR_FRR_PAGES when we remove pages from
>> pcppages.
>>
>> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
>> Cc: David Rientjes <rientjes@google.com>
>> Cc: Jiang Liu <liuj97@gmail.com>
>> Cc: Len Brown <len.brown@intel.com>
>> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>> Cc: Paul Mackerras <paulus@samba.org>
>> Cc: Christoph Lameter <cl@linux.com>
>> Cc: Minchan Kim <minchan.kim@gmail.com>
>> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
>> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
>> Cc: Dave Hansen <dave@linux.vnet.ibm.com>
>> Cc: Mel Gorman <mel@csn.ul.ie>
>> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
>> ---
>>  mm/page_alloc.c | 10 +++++-----
>>  1 file changed, 5 insertions(+), 5 deletions(-)
>>
>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> index 5b74de6..a7cd2d1 100644
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -667,11 +667,13 @@ static void free_pcppages_bulk(struct zone *zone, int count,
>>  			/* MIGRATE_MOVABLE list may include MIGRATE_RESERVEs */
>>  			__free_one_page(page, zone, 0, mt);
>>  			trace_mm_page_pcpu_drain(page, 0, mt);
>> -			if (is_migrate_cma(mt))
>> -				__mod_zone_page_state(zone, NR_FREE_CMA_PAGES, 1);
>> +			if (likely(mt != MIGRATE_ISOLATE)) {
> 
> Hi Congyang,
> 	I think mt != MIGRATE_ISOLATE is always true here,
> page from PCP's migratetype < MIGRATE_PCPTYPES.
> When isolate page, we change pageblock's migratetype to MIGRATE_ISOLATE,
> but set_freepage_migratetype() isn't called.
> Maybe we can use mt = get_pageblock_migratetype() here ?

Yes, you are right. I have sent a fix patch.

Thanks for pointing it out.

Wen Congyang

> 
> Thanks,
> Jianguo Wu.
> 
>> +				__mod_zone_page_state(zone, NR_FREE_PAGES, 1);
>> +				if (is_migrate_cma(mt))
>> +					__mod_zone_page_state(zone, NR_FREE_CMA_PAGES, 1);
>> +			}
>>  		} while (--to_free && --batch_free && !list_empty(list));
>>  	}
>> -	__mod_zone_page_state(zone, NR_FREE_PAGES, count);
>>  	spin_unlock(&zone->lock);
>>  }
>>  
>> @@ -5987,8 +5989,6 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
>>  		list_del(&page->lru);
>>  		rmv_page_order(page);
>>  		zone->free_area[order].nr_free--;
>> -		__mod_zone_page_state(zone, NR_FREE_PAGES,
>> -				      - (1UL << order));
>>  		for (i = 0; i < (1 << order); i++)
>>  			SetPageReserved((page+i));
>>  		pfn += (1 << order);
>>
> 
> 

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diff mbox

Patch

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 5b74de6..a7cd2d1 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -667,11 +667,13 @@  static void free_pcppages_bulk(struct zone *zone, int count,
 			/* MIGRATE_MOVABLE list may include MIGRATE_RESERVEs */
 			__free_one_page(page, zone, 0, mt);
 			trace_mm_page_pcpu_drain(page, 0, mt);
-			if (is_migrate_cma(mt))
-				__mod_zone_page_state(zone, NR_FREE_CMA_PAGES, 1);
+			if (likely(mt != MIGRATE_ISOLATE)) {
+				__mod_zone_page_state(zone, NR_FREE_PAGES, 1);
+				if (is_migrate_cma(mt))
+					__mod_zone_page_state(zone, NR_FREE_CMA_PAGES, 1);
+			}
 		} while (--to_free && --batch_free && !list_empty(list));
 	}
-	__mod_zone_page_state(zone, NR_FREE_PAGES, count);
 	spin_unlock(&zone->lock);
 }
 
@@ -5987,8 +5989,6 @@  __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
 		list_del(&page->lru);
 		rmv_page_order(page);
 		zone->free_area[order].nr_free--;
-		__mod_zone_page_state(zone, NR_FREE_PAGES,
-				      - (1UL << order));
 		for (i = 0; i < (1 << order); i++)
 			SetPageReserved((page+i));
 		pfn += (1 << order);