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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: "Chen, Yu C" <yu.c.chen@intel.com>, Ingo Molnar <mingo@kernel.org>
Cc: kernel test robot <oliver.sang@intel.com>,
	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: [PATCH] lib/smp_processor_id: Make migration check unconditional of SMP
Date: Thu, 10 Jul 2025 10:27:48 +0200	[thread overview]
Message-ID: <20250710082748.-DPO1rjO@linutronix.de> (raw)
In-Reply-To: <20250710081114.5wnABNG7@linutronix.de>

Commit cac5cefbade90 ("sched/smp: Make SMP unconditional")
migrate_disable() even on UP builds.
Commit 06ddd17521bf1 ("sched/smp: Always define is_percpu_thread() and
scheduler_ipi()") made is_percpu_thread() check the affinity mask
instead replying always true for UP mask.

As a consequence smp_processor_id() now complains if invoked within a
migrate_disable() section because is_percpu_thread() checks its mask and
the migration check is left out.

Make migration check unconditional of SMP.

Fixes: cac5cefbade90 ("sched/smp: Make SMP unconditional")
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202507100448.6b88d6f1-lkp@intel.com
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 lib/smp_processor_id.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/lib/smp_processor_id.c b/lib/smp_processor_id.c
index a2bb7738c373c..94b3f6b195388 100644
--- a/lib/smp_processor_id.c
+++ b/lib/smp_processor_id.c
@@ -22,10 +22,8 @@ unsigned int check_preemption_disabled(const char *what1, const char *what2)
 	if (is_percpu_thread())
 		goto out;
 
-#ifdef CONFIG_SMP
 	if (current->migration_disabled)
 		goto out;
-#endif
 
 	/*
 	 * It is valid to assume CPU-locality during early bootup:
-- 
2.50.0


  reply	other threads:[~2025-07-10  8:27 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-07-10  2:58 [tip:sched/core] [sched/smp] 06ddd17521: BUG:using_smp_processor_id()in_preemptible kernel test robot
2025-07-10  3:18 ` Chen, Yu C
2025-07-10  6:25   ` Sebastian Andrzej Siewior
2025-07-10  8:00     ` Chen, Yu C
2025-07-10  8:11       ` Sebastian Andrzej Siewior
2025-07-10  8:27         ` Sebastian Andrzej Siewior [this message]
2025-07-10  8:32           ` [PATCH] lib/smp_processor_id: Make migration check unconditional of SMP Chen, Yu C
2025-07-10 10:13             ` Peter Zijlstra
2025-07-11 12:41           ` [tip: sched/core] " tip-bot2 for Sebastian Andrzej Siewior
2025-07-10  8:29         ` [tip:sched/core] [sched/smp] 06ddd17521: BUG:using_smp_processor_id()in_preemptible Chen, Yu C
2025-07-10 10:47           ` Sebastian Andrzej Siewior
2025-07-10 11:31             ` Chen, Yu C

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