Re: [PATCH v3 3/3] sched_ext: Guarantee rq lock on scx_bpf_cpu_rq()

[Jake Hillion]

On Sun, Aug 10, 2025 at 12:52:53PM +0200, Andrea Righi wrote:
> Yeah, this is not nice, but they would be still broken though, in PATCH 1/3
> we force schedulers to check for NULL and, if they don't, the verifier
> won't be happy, so this already breaks existing binaries.

I ran some testing on the sched_ext for-next branch, and scx_cosmos is
breaking in cosmos_init including the latest changes. I believe it kicks
off a timer in init, which indirectly calls
`scx_bpf_cpu_rq(cpu)->curr->flags & PF_IDLE`. This should be NULL
checked, but old binaries breaking is pretty inconvenient for new users.

As Andrea says, this is the already merged patch triggering this.

Thanks,
Jake.