lkml.org 
[lkml]   [2013]   [Dec]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH v13 01/16] memcg: make cache index determination more robust
    Date
    From: Glauber Costa <glommer@openvz.org>

    I caught myself doing something like the following outside memcg core:

    memcg_id = -1;
    if (memcg && memcg_kmem_is_active(memcg))
    memcg_id = memcg_cache_id(memcg);

    to be able to handle all possible memcgs in a sane manner. In particular, the
    root cache will have kmemcg_id = -1 (just because we don't call memcg_kmem_init
    to the root cache since it is not limitable). We have always coped with that by
    making sure we sanitize which cache is passed to memcg_cache_id. Although this
    example is given for root, what we really need to know is whether or not a
    cache is kmem active.

    But outside the memcg core testing for root, for instance, is not trivial since
    we don't export mem_cgroup_is_root. I ended up realizing that this tests really
    belong inside memcg_cache_id. This patch moves a similar but stronger test
    inside memcg_cache_id and make sure it always return a meaningful value.

    Signed-off-by: Glauber Costa <glommer@openvz.org>
    Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
    Cc: Johannes Weiner <hannes@cmpxchg.org>
    Cc: Michal Hocko <mhocko@suse.cz>
    Cc: Balbir Singh <bsingharora@gmail.com>
    Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
    ---
    mm/memcontrol.c | 4 +++-
    1 file changed, 3 insertions(+), 1 deletion(-)

    diff --git a/mm/memcontrol.c b/mm/memcontrol.c
    index f1a0ae6..02b5176 100644
    --- a/mm/memcontrol.c
    +++ b/mm/memcontrol.c
    @@ -3073,7 +3073,9 @@ void memcg_cache_list_add(struct mem_cgroup *memcg, struct kmem_cache *cachep)
    */
    int memcg_cache_id(struct mem_cgroup *memcg)
    {
    - return memcg ? memcg->kmemcg_id : -1;
    + if (!memcg || !memcg_can_account_kmem(memcg))
    + return -1;
    + return memcg->kmemcg_id;
    }

    /*
    --
    1.7.10.4


    \
     
     \ /
      Last update: 2013-12-09 10:01    [W:4.193 / U:0.020 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site