Re: [PATCH] mm: compaction: some tracepoints should be defined only when CONFIG_COMPACTION is set

[Yafang Shao]

On Wed, Mar 13, 2019 at 12:44 AM Michal Hocko <mhocko@xxxxxxxxxx> wrote:
>
> On Wed 13-03-19 00:29:57, Yafang Shao wrote:
> > On Wed, Mar 13, 2019 at 12:18 AM Michal Hocko <mhocko@xxxxxxxxxx> wrote:
> > >
> > > On Sat 02-03-19 12:38:58, Yafang Shao wrote:
> > > > Only mm_compaction_isolate_{free, migrate}pages may be used when
> > > > CONFIG_COMPACTION is not set.
> > > > All others are used only when CONFIG_COMPACTION is set.
> > >
> > > Why is this an improvement?
> > >
> >
> > After this change, if CONFIG_COMPACTION is not set, the tracepoints
> > that only work when CONFIG_COMPACTION is set will not be exposed to
> > the usespace.
> > Without this change, they will always be expose in debugfs no matter
> > CONFIG_COMPACTION is set or not.
>
> And this is exactly something that the changelog should mention. I
> wasn't aware that we do export tracepoints even when they are not used
> by any code path. This whole macro based programming is just a black
> magic.
> --

Sure, I will modify the changelog and send v2.

Thanks
Yafang