On Thu, Jan 19, 2012 at 6:07 AM, Michal Hocko <mhocko@xxxxxxx> wrote:
> On Fri 13-01-12 17:42:23, KAMEZAWA Hiroyuki wrote:
>> From a9b51d6204d7f8714173c46a306caf413ad25d4e Mon Sep 17 00:00:00 2001
>> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
>> Date: Thu, 12 Jan 2012 18:40:26 +0900
>> Subject: [PATCH 5/7] memcg: remove PCG_FILE_MAPPED
>>
>> Because we can update page's status and memcg's statistics without
>> race with move_account, this flag is unnecessary.
>
> I would really appreciate a little bit more description ;)
>
> 8725d541 [memcg: fix race in file_mapped accounting] has added the
> flag to resolve a race when a move_account happened between page's
> mapcount has been updated and this has been accounted to memcg.
> This, however, cannot happen anymore because mem_cgroup_update_page_stat
> is always enclosed by mem_cgroup_begin_update_page_stat and
> mem_cgroup_end_update_page_stat along with the mapcount update.
Agree on better documentation.
>
>>
>> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
>
> Other than that looks good and nice to see another one go away.
> I will add my ack along with the patches which this depend on once they
> settle down if you don't mind
>
> Thanks
>
>> ---
>> include/linux/page_cgroup.h | 6 ------
>> mm/memcontrol.c | 6 +-----
>> 2 files changed, 1 insertions(+), 11 deletions(-)
>>
>> diff --git a/include/linux/page_cgroup.h b/include/linux/page_cgroup.h
>> index 5dba799..0b9a48a 100644
>> --- a/include/linux/page_cgroup.h
>> +++ b/include/linux/page_cgroup.h
>> @@ -7,8 +7,6 @@ enum {
>> PCG_CACHE, /* charged as cache */
>> PCG_USED, /* this object is in use. */
>> PCG_MIGRATION, /* under page migration */
>> - /* flags for mem_cgroup and file and I/O status */
>> - PCG_FILE_MAPPED, /* page is accounted as "mapped" */
>> __NR_PCG_FLAGS,
>> };
>>
>> @@ -72,10 +70,6 @@ TESTPCGFLAG(Used, USED)
>> CLEARPCGFLAG(Used, USED)
>> SETPCGFLAG(Used, USED)
>>
>> -SETPCGFLAG(FileMapped, FILE_MAPPED)
>> -CLEARPCGFLAG(FileMapped, FILE_MAPPED)
>> -TESTPCGFLAG(FileMapped, FILE_MAPPED)
>> -
>> SETPCGFLAG(Migration, MIGRATION)
>> CLEARPCGFLAG(Migration, MIGRATION)
>> TESTPCGFLAG(Migration, MIGRATION)
>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>> index 30ef810..a96800d 100644
>> --- a/mm/memcontrol.c
>> +++ b/mm/memcontrol.c
>> @@ -1952,10 +1952,6 @@ void mem_cgroup_update_page_stat(struct page *page,
>>
>> switch (idx) {
>> case MEMCG_NR_FILE_MAPPED:
>> - if (val > 0)
>> - SetPageCgroupFileMapped(pc);
>> - else if (!page_mapped(page))
>> - ClearPageCgroupFileMapped(pc);
>> idx = MEM_CGROUP_STAT_FILE_MAPPED;
>> break;
>> default:
>> @@ -2606,7 +2602,7 @@ static int mem_cgroup_move_account(struct page *page,
>>
>> mem_cgroup_account_move_wlock(page, &flags);
>>
>> - if (PageCgroupFileMapped(pc)) {
>> + if (page_mapcount(page)) {
Does it includes anon pages , should it be
if (page_mapped(page) && !PageAnon(page))
--Ying
>> /* Update mapped_file data for mem_cgroup */
>> preempt_disable();
>> __this_cpu_dec(from->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
>> --
>> 1.7.4.1
>>
>>
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>
> --
> Michal Hocko
> SUSE Labs
> SUSE LINUX s.r.o.
> Lihovarska 1060/12
> 190 00 Praha 9
> Czech Republic
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