Re: [PATCH v4 3/4] mm/page_owner: Print memcg information

[Waiman Long]

On 2/7/22 14:09, Andrew Morton wrote:
> On Mon, 7 Feb 2022 18:20:04 +0100 Michal Hocko <mhocko@xxxxxxxx> wrote:
>
> > On Thu 03-02-22 14:03:58, Waiman Long wrote:
> > > On 2/3/22 07:46, Michal Hocko wrote:
> > > > On Wed 02-02-22 15:30:35, Waiman Long wrote:
> > > > [...]
> > ...
> > > > > +	online = (memcg->css.flags & CSS_ONLINE);
> > > > > +	cgroup_name(memcg->css.cgroup, name, sizeof(name));
> > > > Is there any specific reason to use another buffer allocated on the
> > > > stack? Also 80B seems too short to cover NAME_MAX.
> > > >
> > > > Nothing else jumped at me.
> > > I suppose we can print directly into kbuf with cgroup_name(), but using a
> > > separate buffer is easier to read and understand. 79 characters should be
> > > enough for most cgroup names. Some auto-generated names with some kind of
> > > embedded uuids may be longer than that, but the random sequence of hex
> > > digits that may be missing do not convey much information for identification
> > > purpose. We can always increase the buffer length later if it turns out to
> > > be an issue.
> > Cutting a name short sounds like a source of confusion and there doesn't
> > seem to be any good reason for that.
> Yes.  If we give them 79 characters, someone will go and want 94.  If
> we can prevent this once and for ever, let's please do so.

Sure. Will send a version with that change.

Cheers,
Longman

>