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From: Daniel Bristot de Oliveira <bristot@kernel.org>
To: Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Juri Lelli <juri.lelli@redhat.com>,
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	Steven Rostedt <rostedt@goodmis.org>,
	Ben Segall <bsegall@google.com>,
	Mel Gorman <mgorman@suse.de>,
	Daniel Bristot de Oliveira <bristot@redhat.com>,
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	Thomas Gleixner <tglx@linutronix.de>,
	Joel Fernandes <joel@joelfernandes.org>,
	Vineeth Pillai <vineeth@bitbyteword.org>,
	Shuah Khan <skhan@linuxfoundation.org>,
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	Suleiman Souhlal <suleiman@google.com>,
	Youssef Esmat <youssefesmat@google.com>,
	stable@vger.kernel.org
Subject: [PATCH V7 2/9] sched/core: Add clearing of ->dl_server in put_prev_task_balance()
Date: Mon, 27 May 2024 14:06:48 +0200
Message-ID: <d184d554434bedbad0581cb34656582d78655150.1716811044.git.bristot@kernel.org>
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From: "Joel Fernandes (Google)" <joel@joelfernandes.org>

Paths using put_prev_task_balance() need to do a pick shortly
after. Make sure they also clear the ->dl_server on prev as a
part of that.

Cc: stable@vger.kernel.org
Fixes: 63ba8422f876 ("sched/deadline: Introduce deadline servers")
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
---
 kernel/sched/core.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index bcf2c4cc0522..08c409457152 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6006,6 +6006,14 @@ static void put_prev_task_balance(struct rq *rq, struct task_struct *prev,
 #endif
 
 	put_prev_task(rq, prev);
+
+	/*
+	 * We've updated @prev and no longer need the server link, clear it.
+	 * Must be done before ->pick_next_task() because that can (re)set
+	 * ->dl_server.
+	 */
+	if (prev->dl_server)
+		prev->dl_server = NULL;
 }
 
 /*
@@ -6049,14 +6057,6 @@ __pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
 restart:
 	put_prev_task_balance(rq, prev, rf);
 
-	/*
-	 * We've updated @prev and no longer need the server link, clear it.
-	 * Must be done before ->pick_next_task() because that can (re)set
-	 * ->dl_server.
-	 */
-	if (prev->dl_server)
-		prev->dl_server = NULL;
-
 	for_each_class(class) {
 		p = class->pick_next_task(rq);
 		if (p)
-- 
2.45.1