Re: [PATCH] memcg: Remove memcg_cgroup::id from IDR on mem_cgroup_css_alloc() failure

[Vladimir Davydov]

On Fri, Jul 27, 2018 at 03:31:34PM -0400, Johannes Weiner wrote:
> That said, the lifetime of the root reference on the ID is the online
> state, we put that in css_offline. Is there a reason we need to have
> the ID ready and the memcg in the IDR before onlining it?

I fail to see any reason for this in the code.

> Can we do something like this and not mess with the alloc/free
> sequence at all?

I guess so, and this definitely looks better to me.