From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Subject: Re: [PATCH v8 3/4] cgroups: allow a cgroup subsystem to reject a fork
Date: Mon, 6 Apr 2015 11:05:36 -0400
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To: Aleksa Sarai <cyphar-gVpy/LI/lHzQT0dZR+AlfA@public.gmane.org>
Cc: lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org, mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org, richard-/L3Ra7n9ekc@public.gmane.org, =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org

Hello, Aleksa.

On Fri, Apr 03, 2015 at 10:42:27AM +1100, Aleksa Sarai wrote:
> I tried doing this and the kernel would refuse to boot. I believe it has
> something to do with the ordering of early_init subsystems, but I'm not

Hmmm... yeah, failure in early_init can be tricky to debug.

> entirely sure (this optimisation can be dealt with later [it's non-critical],
> so IMO this should be done in a separate patchset [if at all]). Also, your
> later comments would fix the subsys bitmask problem (we can just pass the
> default %NULL), we don't even need to test the index.

But we'd be adding quite a few loops in relatively hot paths.  I don't
think it's a good idea to send the patches as-are because we can't
debug and fix them properly, right?  If there are hard ordering
dependencies, the range of subsystems which require fork/exit doesn't
have to be at the beginning.

Thanks.

-- 
tejun