Re: [GIT pull] sched/urgent for v5.9-rc2

[Marco Elver]

On Mon, 31 Aug 2020 at 09:24, <peterz@xxxxxxxxxxxxx> wrote:
>
> On Sun, Aug 30, 2020 at 11:54:19AM -0700, Linus Torvalds wrote:
> > On Sun, Aug 30, 2020 at 11:04 AM Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
> > >
> > >  - Make is_idle_task() __always_inline to prevent the compiler from putting
> > >    it out of line into the wrong section because it's used inside noinstr
> > >    sections.
> >
> > What completely broken compiler uninlined that single-instruction function?
> >
> > I've obviously pulled this, but it sounds like there should be a
> > compiler bug-report for this insane behavior.
> >
> > Or is Marco building the kernel without optimizations or something
> > like that? That has not been a supported model, for various good
> > reasons..
>
> I think that was Clang with KCSAN on, KCSAN obviously makes this
> function a little bigger with the instrumentation for the load(s). But
> yes...

I wasn't quite sure myself if it was Clang or GCC, so I re-tested with
the linked config (which says GCC), and it reproduces on both.