• Vladimir Davydov's avatar
    memcg: reparent list_lrus and free kmemcg_id on css offline · 2788cf0c
    Vladimir Davydov authored
    Now, the only reason to keep kmemcg_id till css free is list_lru, which
    uses it to distribute elements between per-memcg lists.  However, it can
    be easily sorted out - we only need to change kmemcg_id of an offline
    cgroup to its parent's id, making further list_lru_add()'s add elements to
    the parent's list, and then move all elements from the offline cgroup's
    list to the one of its parent.  It will work, because a racing
    list_lru_del() does not need to know the list it is deleting the element
    from.  It can decrement the wrong nr_items counter though, but the ongoing
    reparenting will fix it.  After list_lru reparenting is done we are free
    to release kmemcg_id saving a valuable slot in a per-memcg array for new
    Signed-off-by: default avatarVladimir Davydov <vdavydov@parallels.com>
    Cc: Johannes Weiner <hannes@cmpxchg.org>
    Cc: Michal Hocko <mhocko@suse.cz>
    Cc: Tejun Heo <tj@kernel.org>
    Cc: Christoph Lameter <cl@linux.com>
    Cc: Pekka Enberg <penberg@kernel.org>
    Cc: David Rientjes <rientjes@google.com>
    Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
    Cc: Dave Chinner <david@fromorbit.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
list_lru.c 12.2 KB