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

[peterz]

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...