Re: [PATCH 3/4] [BUGFIX] fix memcgroup LRU stat with THP

[Hiroyuki Kamezawa]

2011/1/14 Johannes Weiner <hannes@xxxxxxxxxxx>:
> On Fri, Jan 14, 2011 at 07:10:42PM +0900, KAMEZAWA Hiroyuki wrote:
>> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
>>
>> memroy cgroup's LRU stat should take care of size of pages because
>> Transparent Hugepage inserts hugepage into LRU and zone counter
>> is updeted based on the size of page.
>>
>> If this value is the number wrong, memory reclaim will not work well.
>>
>> Note: only head page of THP's huge page is linked into LRU.
>>
>> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
>> ---
>>  mm/memcontrol.c |   10 ++++++++--
>>  1 file changed, 8 insertions(+), 2 deletions(-)
>>
>> Index: mmotm-0107/mm/memcontrol.c
>> ===================================================================
>> --- mmotm-0107.orig/mm/memcontrol.c
>> +++ mmotm-0107/mm/memcontrol.c
>> @@ -815,7 +815,10 @@ void mem_cgroup_del_lru_list(struct page
>>        * removed from global LRU.
>>        */
>>       mz = page_cgroup_zoneinfo(pc);
>> -     MEM_CGROUP_ZSTAT(mz, lru) -= 1;
>> +     if (!PageTransHuge(page))
>> +             MEM_CGROUP_ZSTAT(mz, lru) -= 1;
>> +     else
>> +             MEM_CGROUP_ZSTAT(mz, lru) -= 1 << compound_order(page);
>
> compound_order() returns 0 for !PG_head pages, that should do the
> right thing without checking PageTransHuge(), right?

You're right. Then, I can remove this 'if'. Thank you.
Hmm, I'll check other places, again.

Regards,
-Kame
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