[PATCH] compaction: Remove mem_cgroup_del_lru

[PATCH] compaction: Remove mem_cgroup_del_lru

[Minchan Kim]

del_page_from_lru_list alreay called mem_cgroup_del_lru.
So we need to call it again. It makes wrong stat of memcg and
even happen VM_BUG_ON hit.

Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
---
 mm/compaction.c |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)

diff --git a/mm/compaction.c b/mm/compaction.c
index 50b0a90..b0fbfdf 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -302,7 +302,6 @@ static unsigned long isolate_migratepages(struct zone *zone,
 		/* Successfully isolated */
 		del_page_from_lru_list(zone, page, page_lru(page));
 		list_add(&page->lru, migratelist);
-		mem_cgroup_del_lru(page);
 		cc->nr_migratepages++;
 		nr_isolated++;
 
-- 
1.7.0.4

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Re: [PATCH] compaction: Remove mem_cgroup_del_lru

[Balbir Singh]

* MinChan Kim <minchan.kim@gmail.com> [2010-12-08 00:01:26]:

> del_page_from_lru_list alreay called mem_cgroup_del_lru.
> So we need to call it again. It makes wrong stat of memcg and
> even happen VM_BUG_ON hit.
> 
> Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> Cc: Mel Gorman <mel@csn.ul.ie>
> Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
> ---


Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
 

-- 
	Three Cheers,
	Balbir

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Re: [PATCH] compaction: Remove mem_cgroup_del_lru

[Andrew Morton]

On Wed,  8 Dec 2010 00:01:26 +0900
Minchan Kim <minchan.kim@gmail.com> wrote:

> del_page_from_lru_list alreay called mem_cgroup_del_lru.
> So we need to call it again. It makes wrong stat of memcg and
> even happen VM_BUG_ON hit.
> 
> Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> Cc: Mel Gorman <mel@csn.ul.ie>
> Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
> ---
>  mm/compaction.c |    1 -
>  1 files changed, 0 insertions(+), 1 deletions(-)
> 
> diff --git a/mm/compaction.c b/mm/compaction.c
> index 50b0a90..b0fbfdf 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -302,7 +302,6 @@ static unsigned long isolate_migratepages(struct zone *zone,
>  		/* Successfully isolated */
>  		del_page_from_lru_list(zone, page, page_lru(page));
>  		list_add(&page->lru, migratelist);
> -		mem_cgroup_del_lru(page);
>  		cc->nr_migratepages++;
>  		nr_isolated++;
>  

err, yes, that looks bad.

This bug is present in 2.6.35 and 2.6.36 afaict, so I tagged the fix
for -stable backporting.

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Re: [PATCH] compaction: Remove mem_cgroup_del_lru

[Minchan Kim]

On Wed, Dec 8, 2010 at 6:53 AM, Andrew Morton <akpm@linux-foundation.org> wrote:
> On Wed,  8 Dec 2010 00:01:26 +0900
> Minchan Kim <minchan.kim@gmail.com> wrote:
>
>> del_page_from_lru_list alreay called mem_cgroup_del_lru.
>> So we need to call it again. It makes wrong stat of memcg and
>> even happen VM_BUG_ON hit.
>>
>> Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
>> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
>> Cc: Mel Gorman <mel@csn.ul.ie>
>> Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
>> ---
>>  mm/compaction.c |    1 -
>>  1 files changed, 0 insertions(+), 1 deletions(-)
>>
>> diff --git a/mm/compaction.c b/mm/compaction.c
>> index 50b0a90..b0fbfdf 100644
>> --- a/mm/compaction.c
>> +++ b/mm/compaction.c
>> @@ -302,7 +302,6 @@ static unsigned long isolate_migratepages(struct zone *zone,
>>               /* Successfully isolated */
>>               del_page_from_lru_list(zone, page, page_lru(page));
>>               list_add(&page->lru, migratelist);
>> -             mem_cgroup_del_lru(page);
>>               cc->nr_migratepages++;
>>               nr_isolated++;
>>
>
> err, yes, that looks bad.
>
> This bug is present in 2.6.35 and 2.6.36 afaict, so I tagged the fix
> for -stable backporting.

Thanks, Andrew.

>
>



-- 
Kind regards,
Minchan Kim

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Re: [PATCH] compaction: Remove mem_cgroup_del_lru

[KAMEZAWA Hiroyuki]

On Wed,  8 Dec 2010 00:01:26 +0900
Minchan Kim <minchan.kim@gmail.com> wrote:

> del_page_from_lru_list alreay called mem_cgroup_del_lru.
> So we need to call it again. It makes wrong stat of memcg and
> even happen VM_BUG_ON hit.
> 
> Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> Cc: Mel Gorman <mel@csn.ul.ie>
> Signed-off-by: Minchan Kim <minchan.kim@gmail.com>

Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

Thank you.


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Re: [PATCH] compaction: Remove mem_cgroup_del_lru

[Mel Gorman]

On Wed, Dec 08, 2010 at 12:01:26AM +0900, Minchan Kim wrote:
> del_page_from_lru_list alreay called mem_cgroup_del_lru.
> So we need to call it again. It makes wrong stat of memcg and
> even happen VM_BUG_ON hit.
> 
> Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> Cc: Mel Gorman <mel@csn.ul.ie>
> Signed-off-by: Minchan Kim <minchan.kim@gmail.com>

Thanks

Acked-by: Mel Gorman <mel@csn.ul.ie>

-- 
Mel Gorman
Part-time Phd Student                          Linux Technology Center
University of Limerick                         IBM Dublin Software Lab

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Re: [PATCH] compaction: Remove mem_cgroup_del_lru

[Johannes Weiner]

On Wed, Dec 08, 2010 at 12:01:26AM +0900, Minchan Kim wrote:
> del_page_from_lru_list alreay called mem_cgroup_del_lru.
> So we need to call it again. It makes wrong stat of memcg and
> even happen VM_BUG_ON hit.
> 
> Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> Cc: Mel Gorman <mel@csn.ul.ie>
> Signed-off-by: Minchan Kim <minchan.kim@gmail.com>

Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>

But regarding the severity of this: shouldn't the second deletion
attempt be caught by the TestClearPageCgroupAcctLRU() early in
mem_cgroup_del_lru_list()?

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Re: [PATCH] compaction: Remove mem_cgroup_del_lru

[Minchan Kim]

On Thu, Dec 9, 2010 at 1:43 AM, Johannes Weiner <hannes@cmpxchg.org> wrote:
> On Wed, Dec 08, 2010 at 12:01:26AM +0900, Minchan Kim wrote:
>> del_page_from_lru_list alreay called mem_cgroup_del_lru.
>> So we need to call it again. It makes wrong stat of memcg and
>> even happen VM_BUG_ON hit.
>>
>> Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
>> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
>> Cc: Mel Gorman <mel@csn.ul.ie>
>> Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
>
> Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
>
> But regarding the severity of this: shouldn't the second deletion
> attempt be caught by the TestClearPageCgroupAcctLRU() early in
> mem_cgroup_del_lru_list()?
>

Right, I missed that.
Andrew, I will resend modified description.

Thanks for careful review again, Hannes.

-- 
Kind regards,
Minchan Kim

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Re: [PATCH] compaction: Remove mem_cgroup_del_lru

[Minchan Kim]

On Wed, Dec 08, 2010 at 12:01:26AM +0900, Minchan Kim wrote:
> del_page_from_lru_list alreay called mem_cgroup_del_lru.
> So we need to call it again. It makes wrong stat of memcg and
> even happen VM_BUG_ON hit.
> 
> Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> Cc: Mel Gorman <mel@csn.ul.ie>
> Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
> ---
>  mm/compaction.c |    1 -
>  1 files changed, 0 insertions(+), 1 deletions(-)
> 
> diff --git a/mm/compaction.c b/mm/compaction.c
> index 50b0a90..b0fbfdf 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -302,7 +302,6 @@ static unsigned long isolate_migratepages(struct zone *zone,
>  		/* Successfully isolated */
>  		del_page_from_lru_list(zone, page, page_lru(page));
>  		list_add(&page->lru, migratelist);
> -		mem_cgroup_del_lru(page);
>  		cc->nr_migratepages++;
>  		nr_isolated++;
>  
> -- 
> 1.7.0.4
> 

Hi Andrew, 
Please drop above(mm-compactionc-avoid-double-mem_cgroup_del_lru.patch)
This is a new version with modified description and added Acked-by.