(2012/11/27 3:47), Michal Hocko wrote:

Current implementation of mem_cgroup_iter has to consider both css and
memcg to find out whether no group has been found (css==NULL - aka the
loop is completed) and that no memcg is associated with the found node
(!memcg - aka css_tryget failed because the group is no longer alive).
This leads to awkward tweaks like tests for css && !memcg to skip the
current node.

It will be much easier if we got rid off css variable altogether and
only rely on memcg. In order to do that the iteration part has to skip
dead nodes. This sounds natural to me and as a nice side effect we will
get a simple invariant that memcg is always alive when non-NULL and all
nodes have been visited otherwise.

We could get rid of the surrounding while loop but keep it in for now to
make review easier. It will go away in the following patch.

Signed-off-by: Michal Hocko <redacted>

Acked-by: KAMEZAWA Hiroyuki <redacted>


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