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由 Michal Hocko 提交于
The 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: NMichal Hocko <mhocko@suse.cz> Acked-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Li Zefan <lizefan@huawei.com> Cc: Ying Han <yinghan@google.com> Cc: Tejun Heo <htejun@gmail.com> Cc: Glauber Costa <glommer@parallels.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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