(2012/04/23 17:28), Anton Vorontsov wrote:
> ...otherwise the we're getting the wrong numbers in usage_in_bytes.
>
> On Mon, Mar 05, 2012 at 09:19:34AM +0900, KAMEZAWA Hiroyuki wrote:
> [...]
>>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>>> index 228d646..c8abdc5 100644
>>> --- a/mm/memcontrol.c
>>> +++ b/mm/memcontrol.c
>>> @@ -3812,6 +3812,9 @@ static inline u64 mem_cgroup_usage(struct mem_cgroup *memcg, bool swap)
>>>
>>> val = mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_CACHE);
>>> val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_RSS);
>>> + val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_FILE_MAPPED);
>>>
>>> 1. Is there any particular reason we don't currently account file mapped
>>> memory in usage_in_bytes?
>>>
>>> To me, MEM_CGROUP_STAT_FILE_MAPPED hunk seems logical even if we
>>> don't use it for lowmemory notifications.
>>>
>>> Plus, it seems that FILE_MAPPED _is_ accounted for the non-root
>>> cgroups, so I guess it's clearly a bug for the root memcg?
>>
>> CACHE includes all file caches. Why do you think FILE_MAPPED is not included in CACHE ?
>
> There were tons of changes in the memcg lately, but I believe the issue
> is still there.
>
> For example, looking into this code flow:
>
> -> page_add_file_rmap() (mm/rmap.c)
> -> mem_cgroup_inc_page_stat(page, MEMCG_NR_FILE_MAPPED) (include/linux/memcontrol.h)
> -> void mem_cgroup_update_page_stat(page, MEMCG_NR_FILE_MAPPED, 1) (mm/memcontrol.c)
>
> And then:
>
> void mem_cgroup_update_page_stat(struct page *page,
> enum mem_cgroup_page_stat_item idx, int val)
> {
> ...
> switch (idx) {
> case MEMCG_NR_FILE_MAPPED:
> idx = MEM_CGROUP_STAT_FILE_MAPPED;
> break;
> default:
> BUG();
> }
>
> this_cpu_add(memcg->stat->count[idx], val);
> ...
> }
>
> So, clearly, this function only bothers updating _FILE_MAPPED only,
> leaving _CACHE alone.
>
> If you're saying that _CACHE meant to include _FILE_MAPPED, then
> I guess the patch down below would be a proper fix then... Otherwise
> we need to be consistent on stats reporting, and either fall-back
> to my original fix (in mem_cgroup_usage()), or think about doing it
> some other way...
>
NACK.
CACHE is updated at charge()/uncharge()...inserting/removing page cache to radix-tree.
Thanks,
-Kame
> Signed-off-by: Anton Vorontsov <anton.vorontsov@xxxxxxxxxx>
> ---
>
> The patch is against current -next.
>
> Thanks,
>
> mm/memcontrol.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 884e936..760ecf5 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -1958,6 +1958,8 @@ void mem_cgroup_update_page_stat(struct page *page,
>
> switch (idx) {
> case MEMCG_NR_FILE_MAPPED:
> + idx = MEM_CGROUP_STAT_CACHE;
> + this_cpu_add(memcg->stat->count[idx], val);
> idx = MEM_CGROUP_STAT_FILE_MAPPED;
> break;
> default:
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