linux-kernel - Re: linux-next: manual merge of the rcu tree with the ftrace tree

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Message-ID: <20251118073508.JdhVECQD@linutronix.de>
Date: Tue, 18 Nov 2025 08:35:08 +0100
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: Yonghong Song <yonghong.song@...ux.dev>
Cc: paulmck@...nel.org, Steven Rostedt <rostedt@...dmis.org>,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	Frederic Weisbecker <frederic@...nel.org>,
	Neeraj Upadhyay <neeraj.upadhyay@...nel.org>,
	Boqun Feng <boqun.feng@...il.com>,
	Uladzislau Rezki <urezki@...il.com>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linux Next Mailing List <linux-next@...r.kernel.org>
Subject: Re: linux-next: manual merge of the rcu tree with the ftrace tree

On 2025-11-14 10:31:45 [-0800], Yonghong Song wrote:
> > I believe that migration needs to be disabled at this point, but I am
> > again adding Yonghong on CC for his perspective.
> 
> Yes, migration needs to be disabled for rt kernel in order to let
> bpf program running properly.

Why is disabling migration special in regard to RT kernels vs !RT?
Why do we need to disable migration given that bpf_prog_run_array()
already does that? Is there a different entry point? 
My point why is it required to disable migration on trace-point entry
for BPF given that the BPF-entry already does so.

Sebastian