linux-kernel - Re: [PATCH v3 2/3] sched_ext: Provide scx_bpf_task_acquire_remote

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Message-ID: <aJoji6OmdoJyfpbc@slm.duckdns.org>
Date: Mon, 11 Aug 2025 07:08:27 -1000
From: Tejun Heo <tj@...nel.org>
To: Christian Loehle <christian.loehle@....com>
Cc: arighi@...dia.com, void@...ifault.com, linux-kernel@...r.kernel.org,
	sched-ext@...ts.linux.dev, changwoo@...lia.com, hodgesd@...a.com,
	mingo@...hat.com, peterz@...radead.org
Subject: Re: [PATCH v3 2/3] sched_ext: Provide
 scx_bpf_task_acquire_remote_curr()

On Sat, Aug 09, 2025 at 09:01:18AM -1000, Tejun Heo wrote:
> On Tue, Aug 05, 2025 at 12:10:35PM +0100, Christian Loehle wrote:
> > Provide scx_bpf_task_acquire_remote_curr() as a way for scx schedulers
> > to check the curr task of a remote rq without assuming its lock is
> > held.
> > 
> > Many scx schedulers make use of scx_bpf_cpu_rq() to check a remote curr
> > (e.g. to see if it should be preempted). This is problematic because
> > scx_bpf_cpu_rq() provides access to all fields of struct rq, most of
> > which aren't safe to use without holding the associated rq lock.
> > 
> > Signed-off-by: Christian Loehle <christian.loehle@....com>
> 
> Applied 1-2 to sched_ext/for-6.17-fixes.

Reverted due to compatibility issues. Let's try again with warnings as
discussed in the other subthread.

Thanks.

-- 
tejun