Hi all, this is a second version of the patchset previously posted here: https://lkml.org/lkml/2012/11/13/335 The patch set tries to make mem_cgroup_iter saner in the way how it walks hierarchies. css->id based traversal is far from being ideal as it is not deterministic because it depends on the creation ordering. Diffstat looks promising but it is fair the say that the biggest cleanup is just css_get_next removal. The memcg code has grown a bit but I think it is worth the resulting outcome (the sanity ;)). The first patch fixes a potential misbehaving which I haven't seen but the fix is needed for the later patches anyway. We could take it alone as well but I do not have any bug report to base the fix on. The second one is also preparatory and it is new to the series. The third patch replaces css_get_next by cgroup iterators which are scheduled for 3.8 in Tejun's tree and I depend on the following two patches: fe1e904c cgroup: implement generic child / descendant walk macros 7e187c6c cgroup: use rculist ops for cgroup->children The third and fourth patches are an attempt for simplification of the mem_cgroup_iter. css juggling is removed and the iteration logic is moved to a helper so that the reference counting and iteration are separated. The last patch just removes css_get_next as there is no user for it any longer. I am also thinking that leaf-to-root iteration makes more sense but this patch is not included in the series yet because I have to think some more about the justification. I have dropped "[RFC 4/5] memcg: clean up mem_cgroup_iter" (https://lkml.org/lkml/2012/11/13/333) because testing quickly shown that my thinking was flawed and VM_BUG_ON(!prev && !memcg) triggered very quickly. This also suggest that this version has seen some testing, unlike the previous one ;) The test was simple but I guess it exercised this code path quite heavily. A (limit = 280M, use_hierarchy=true) / | \ B C D (all have 100M limit) and independent kernel build (with the full distribution config) in all children groups. This triggers both children only and hierarchical reclaims. The shortlog says: Michal Hocko (6): memcg: synchronize per-zone iterator access by a spinlock memcg: keep prev's css alive for the whole mem_cgroup_iter memcg: rework mem_cgroup_iter to use cgroup iterators memcg: simplify mem_cgroup_iter memcg: further simplify mem_cgroup_iter cgroup: remove css_get_next And diffstat: include/linux/cgroup.h | 7 --- kernel/cgroup.c | 49 --------------------- mm/memcontrol.c | 110 +++++++++++++++++++++++++++++++++++++----------- 3 files changed, 86 insertions(+), 80 deletions(-) -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>