[Devel] Re: [PATCH 02/10] memcg: Uncharge all kmem when deleting a cgroup.

[Suleiman Souhlal]

On Tue, Feb 28, 2012 at 10:22 PM, KAMEZAWA Hiroyuki
<kamezawa.hiroyu at jp.fujitsu.com> wrote:
> On Mon, 27 Feb 2012 14:58:45 -0800
> Suleiman Souhlal <ssouhlal at FreeBSD.org> wrote:
>
>> A later patch will also use this to move the accounting to the root
>> cgroup.
>>
>> Signed-off-by: Suleiman Souhlal <suleiman at google.com>
>> ---
>>  mm/memcontrol.c |   30 +++++++++++++++++++++++++++++-
>>  1 files changed, 29 insertions(+), 1 deletions(-)
>>
>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>> index 11e31d6..6f44fcb 100644
>> --- a/mm/memcontrol.c
>> +++ b/mm/memcontrol.c
>> @@ -378,6 +378,7 @@ static void mem_cgroup_get(struct mem_cgroup *memcg);
>>  static void mem_cgroup_put(struct mem_cgroup *memcg);
>>  static void memcg_kmem_init(struct mem_cgroup *memcg,
>>      struct mem_cgroup *parent);
>> +static void memcg_kmem_move(struct mem_cgroup *memcg);
>>
>>  /* Writing them here to avoid exposing memcg's inner layout */
>>  #ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
>> @@ -3674,6 +3675,7 @@ static int mem_cgroup_force_empty(struct mem_cgroup *memcg, bool free_all)
>>       int ret;
>>       int node, zid, shrink;
>>       int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
>> +     unsigned long usage;
>>       struct cgroup *cgrp = memcg->css.cgroup;
>>
>>       css_get(&memcg->css);
>> @@ -3693,6 +3695,8 @@ move_account:
>>               /* This is for making all *used* pages to be on LRU. */
>>               lru_add_drain_all();
>>               drain_all_stock_sync(memcg);
>> +             if (!free_all)
>> +                     memcg_kmem_move(memcg);
>>               ret = 0;
>>               mem_cgroup_start_move(memcg);
>>               for_each_node_state(node, N_HIGH_MEMORY) {
>> @@ -3714,8 +3718,13 @@ move_account:
>>               if (ret == -ENOMEM)
>>                       goto try_to_free;
>>               cond_resched();
>> +             usage = memcg->res.usage;
>> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
>> +             if (free_all && !memcg->independent_kmem_limit)
>> +                     usage -= memcg->kmem_bytes.usage;
>> +#endif
>
> Why we need this even if memcg_kmem_move() does uncharge ?

We need it when manually calling force_empty.

-- Suleiman