linux-kernel - Re: [PATCH 2/4] mm: Move nr_deactivate accounting to shrink_active

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Date:   Thu, 14 Feb 2019 13:30:38 +0300
From:   Kirill Tkhai <ktkhai@...tuozzo.com>
To:     Daniel Jordan <daniel.m.jordan@...cle.com>
Cc:     akpm@...ux-foundation.org, mhocko@...e.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] mm: Move nr_deactivate accounting to
 shrink_active_list()

On 13.02.2019 22:13, Daniel Jordan wrote:
> On Tue, Feb 12, 2019 at 06:14:05PM +0300, Kirill Tkhai wrote:
>> We know, which LRU is not active.
> 
> s/,//
> 
>>
>> Signed-off-by: Kirill Tkhai <ktkhai@...tuozzo.com>
>> ---
>>  mm/vmscan.c |   10 ++++------
>>  1 file changed, 4 insertions(+), 6 deletions(-)
>>
>> diff --git a/mm/vmscan.c b/mm/vmscan.c
>> index 84542004a277..8d7d55e71511 100644
>> --- a/mm/vmscan.c
>> +++ b/mm/vmscan.c
>> @@ -2040,12 +2040,6 @@ static unsigned move_active_pages_to_lru(struct lruvec *lruvec,
>>  		}
>>  	}
>>  
>> -	if (!is_active_lru(lru)) {
>> -		__count_vm_events(PGDEACTIVATE, nr_moved);
>> -		count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE,
>> -				   nr_moved);
>> -	}
>> -
>>  	return nr_moved;
>>  }
>>  
>> @@ -2137,6 +2131,10 @@ static void shrink_active_list(unsigned long nr_to_scan,
>>  
>>  	nr_activate = move_active_pages_to_lru(lruvec, &l_active, &l_hold, lru);
>>  	nr_deactivate = move_active_pages_to_lru(lruvec, &l_inactive, &l_hold, lru - LRU_ACTIVE);
>> +
>> +	__count_vm_events(PGDEACTIVATE, nr_deactivate);
>> +	__count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE, nr_deactivate);
> 
> Nice, you're using the irq-unsafe one since irqs are already disabled.  I guess
> this was missed in c3cc39118c361.  Do you want to insert a patch before this
> one that converts all instances of this pattern in vmscan.c over?

I had that in plan, but I'm not sure I want to do that in this patchset. Maybe,
something next later on top of this.

> There's a similar oversight in lru_lazyfree_fn with count_memcg_page_event, but
> that'd mean __count_memcg_page_event which is probably overkill.