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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: "Chen, Yu C" <yu.c.chen@intel.com>
Cc: kernel test robot <oliver.sang@intel.com>,
	Ingo Molnar <mingo@kernel.org>, oe-lkp@lists.linux.dev,
	lkp@intel.com, linux-kernel@vger.kernel.org, x86@kernel.org,
	Peter Zijlstra <peterz@infradead.org>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Juri Lelli <juri.lelli@redhat.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Mel Gorman <mgorman@suse.de>,
	Shrikanth Hegde <sshegde@linux.ibm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Valentin Schneider <vschneid@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	aubrey.li@linux.intel.com
Subject: Re: [tip:sched/core] [sched/smp] 06ddd17521:
 BUG:using_smp_processor_id()in_preemptible
Message-ID: <20250710081114.5wnABNG7@linutronix.de>
References: <202507100448.6b88d6f1-lkp@intel.com>
 <6cf071f3-ff5b-4025-8ce7-2f2cceb03984@intel.com>
 <20250710062528.T-Obm39T@linutronix.de>
 <292e70ed-aae5-4f52-8f85-80cba7ff301d@intel.com>
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In-Reply-To: <292e70ed-aae5-4f52-8f85-80cba7ff301d@intel.com>

On 2025-07-10 16:00:46 [+0800], Chen, Yu C wrote:
> migrate_disable() disables the task migration between CPUs by restricting
> the task's affinity, but it does not disable the preemption on single
> CPUs IMO. The scope of guard(preempt)() in migrate_disable() is just
> within the migrate_disable(). debug_smp_processor_id() warns when the
> preemption is enabled.

does migrate_disable() really have no effect on
debug_smp_processor_id()?

> Thanks,
> Chenyu
Sebastian