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Date: Wed, 20 May 2026 08:09:04 -1000
From: Tejun Heo <tj@kernel.org>
To: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	Valentin Schneider <vschneid@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
	K Prateek Nayak <kprateek.nayak@amd.com>,
	Kyle McMartin <jkkm@meta.com>
Subject: Re: [PATCH v2] sched/rt: Have RT_PUSH_IPI be default off for non
 PREEMPT_RT
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In-Reply-To: <310c1f04-562e-4e81-9d39-0f28e1cc414c@linux.ibm.com>

On Wed, May 20, 2026 at 10:34:35PM +0530, Shrikanth Hegde wrote:
> By any chance it is running with preempt=none/voluntary?
> If so it might never call schedule until it goes back to user space.

I think this might be it. In the production dump, the locked up cpus were
often running btrfs compression / decompression. The kernel is PREEMPT_NONE
and while that path has resched_curr()'s, with high enough irq frequency, it
wouldn't be that difficult to catch the cpu enough times before it reaches
the resched point.

Thanks.

-- 
tejun