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From: Tejun Heo <tj@kernel.org>
To: Jake Hillion <jake@hillion.co.uk>
Cc: Andrea Righi <arighi@nvidia.com>,
	Christian Loehle <christian.loehle@arm.com>,
	void@manifault.com, linux-kernel@vger.kernel.org,
	sched-ext@lists.linux.dev, changwoo@igalia.com, hodgesd@meta.com,
	mingo@redhat.com, peterz@infradead.org
Subject: Re: [PATCH v3 3/3] sched_ext: Guarantee rq lock on scx_bpf_cpu_rq()
Date: Mon, 11 Aug 2025 06:51:10 -1000	[thread overview]
Message-ID: <aJoffsJn0tbJrwcs@slm.duckdns.org> (raw)
In-Reply-To: <y23etey3foin5nrxgj6e4g373b3ap6oxqa5rrvuvwyus3umw5s@bgh3d6uuga5t>

On Mon, Aug 11, 2025 at 03:35:05PM +0100, Jake Hillion wrote:
> 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.

Lemme revert that. I don't think we should introduce breaking changes
without grace period.

Thanks.

-- 
tejun

  reply	other threads:[~2025-08-11 16:51 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-08-05 11:10 [PATCH v3 0/3] sched_ext: Harden scx_bpf_cpu_rq() Christian Loehle
2025-08-05 11:10 ` [PATCH v3 1/3] sched_ext: Mark scx_bpf_cpu_rq as NULL returnable Christian Loehle
2025-08-05 11:10 ` [PATCH v3 2/3] sched_ext: Provide scx_bpf_task_acquire_remote_curr() Christian Loehle
2025-08-09 19:01   ` Tejun Heo
2025-08-11 17:08     ` Tejun Heo
2025-08-05 11:10 ` [PATCH v3 3/3] sched_ext: Guarantee rq lock on scx_bpf_cpu_rq() Christian Loehle
2025-08-09 19:03   ` Tejun Heo
2025-08-10 10:52     ` Andrea Righi
2025-08-10 22:18       ` Christian Loehle
2025-08-11 16:52         ` Tejun Heo
2025-08-11 14:35       ` Jake Hillion
2025-08-11 16:51         ` Tejun Heo [this message]
2025-08-12 13:31         ` Andrea Righi
2025-08-05 14:33 ` [PATCH v3 0/3] sched_ext: Harden scx_bpf_cpu_rq() Andrea Righi

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