Messages in this thread | | | Date | Tue, 31 Jul 2018 16:39:08 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] memcg: Remove memcg_cgroup::id from IDR on mem_cgroup_css_alloc() failure |
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On Mon, 30 Jul 2018 11:31:13 -0400 Johannes Weiner <hannes@cmpxchg.org> wrote:
> Subject: [PATCH] mm: memcontrol: simplify memcg idr allocation and error > unwinding > > The memcg ID is allocated early in the multi-step memcg creation > process, which needs 2-step ID allocation and IDR publishing, as well > as two separate IDR cleanup/unwind sites on error. > > Defer the IDR allocation until the last second during onlining to > eliminate all this complexity. There is no requirement to have the ID > and IDR entry earlier than that. And the root reference to the ID is > put in the offline path, so this matches nicely.
This patch isn't aware of Kirill's later "mm, memcg: assign memcg-aware shrinkers bitmap to memcg", which altered mem_cgroup_css_online():
@@ -4356,6 +4470,11 @@ static int mem_cgroup_css_online(struct { struct mem_cgroup *memcg = mem_cgroup_from_css(css); + if (memcg_alloc_shrinker_maps(memcg)) { + mem_cgroup_id_remove(memcg); + return -ENOMEM; + } + /* Online state pins memcg ID, memcg ID pins CSS */ atomic_set(&memcg->id.ref, 1); css_get(css);
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