Re: [PATCH v6 2/3] memcg: move memcg reclaimable page into tail of inactive list

[Minchan Kim <minchan.kim@gmail.com>]

On Mon, Feb 21, 2011 at 5:40 PM, Johannes Weiner <hannes@cmpxchg.org> wrote:
> On Sun, Feb 20, 2011 at 11:43:37PM +0900, Minchan Kim wrote:
>> --- a/mm/memcontrol.c
>> +++ b/mm/memcontrol.c
>> @@ -813,6 +813,33 @@ void mem_cgroup_del_lru(struct page *page)
>>       mem_cgroup_del_lru_list(page, page_lru(page));
>>  }
>>
>> +/*
>> + * Writeback is about to end against a page which has been marked for immediate
>> + * reclaim.  If it still appears to be reclaimable, move it to the tail of the
>> + * inactive list.
>> + */
>> +void mem_cgroup_rotate_reclaimable_page(struct page *page)
>> +{
>> +     struct mem_cgroup_per_zone *mz;
>> +     struct page_cgroup *pc;
>> +     enum lru_list lru = page_lru(page);
>> +
>> +     if (mem_cgroup_disabled())
>> +             return;
>> +
>> +     pc = lookup_page_cgroup(page);
>> +     /*
>> +      * Used bit is set without atomic ops but after smp_wmb().
>> +      * For making pc->mem_cgroup visible, insert smp_rmb() here.
>> +      */
>> +     smp_rmb();
>> +     /* unused or root page is not rotated. */
>> +     if (!PageCgroupUsed(pc) || mem_cgroup_is_root(pc->mem_cgroup))
>> +             return;
>
> The placement of this barrier is confused and has been fixed up in the
> meantime in other places.  It has to be between PageCgroupUsed() and
> accessing pc->mem_cgroup.  You can look at the other memcg lru
> functions for reference.

Yes. I saw your patch at that time but forgot it.
I will resend fixed version.
Thanks.

-- 
Kind regards,
Minchan Kim

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