Re: [PATCH cgroup/for-4.8] cgroup: allow NULL return from ss->css_alloc()

[Johannes Weiner]

On Tue, Jun 21, 2016 at 01:06:24PM -0400, Tejun Heo wrote:
> cgroup core expected css_alloc to return an ERR_PTR value on failure
> and caused NULL deref if it returned NULL.  It's an easy mistake to
> make from an alloc function and there's no ambiguity in what's being
> indicated.  Update css_create() so that it interprets NULL return from
> css_alloc as -ENOMEM.
> 
> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>

Would it be better to remove the error code instead and have everybody
return NULL? AFAICS, everybody is returning either the object or the
-ENOMEM error code right now.

What error condition is there for an allocation function?