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From: Frederic Weisbecker <frederic@kernel.org>
To: LKML <linux-kernel@vger.kernel.org>
Cc: "Paul E. McKenney" <paulmck@kernel.org>,
	Boqun Feng <boqun.feng@gmail.com>,
	Joel Fernandes <joel@joelfernandes.org>,
	Josh Triplett <josh@joshtriplett.org>,
	Lai Jiangshan <jiangshanlai@gmail.com>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Neeraj Upadhyay <neeraj.upadhyay@amd.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Uladzislau Rezki <urezki@gmail.com>,
	Zqiang <qiang.zhang1211@gmail.com>, rcu <rcu@vger.kernel.org>,
	Frederic Weisbecker <frederic@kernel.org>
Subject: [PATCH 2/6] refscale: Correct affinity check
Date: Wed,  6 Nov 2024 17:02:19 +0100	[thread overview]
Message-ID: <20241106160223.42119-3-frederic@kernel.org> (raw)
In-Reply-To: <20241106160223.42119-1-frederic@kernel.org>

From: "Paul E. McKenney" <paulmck@kernel.org>

The current affinity check works fine until there are more reader
processes than CPUs, at which point the affinity check is looking for
non-existent CPUs.  This commit therefore applies the same modulus to
the check as is present in the set_cpus_allowed_ptr() call.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 kernel/rcu/refscale.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c
index 0db9db73f57f..25910ebe95c0 100644
--- a/kernel/rcu/refscale.c
+++ b/kernel/rcu/refscale.c
@@ -829,7 +829,7 @@ ref_scale_reader(void *arg)
 		goto end;
 
 	// Make sure that the CPU is affinitized appropriately during testing.
-	WARN_ON_ONCE(raw_smp_processor_id() != me);
+	WARN_ON_ONCE(raw_smp_processor_id() != me % nr_cpu_ids);
 
 	WRITE_ONCE(rt->start_reader, 0);
 	if (!atomic_dec_return(&n_started))
-- 
2.46.0


  parent reply	other threads:[~2024-11-06 16:02 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-11-06 16:02 [PATCH 0/6] RCU torture for v6.13 Frederic Weisbecker
2024-11-06 16:02 ` [PATCH 1/6] torture: Add --no-affinity parameter to kvm.sh Frederic Weisbecker
2024-11-06 16:02 ` Frederic Weisbecker [this message]
2024-11-06 16:02 ` [PATCH 3/6] rcuscale: Add guest_os_delay module parameter Frederic Weisbecker
2024-11-06 16:02 ` [PATCH 4/6] rcutorture: Avoid printing cpu=-1 for no-fault RCU boost failure Frederic Weisbecker
2024-11-06 16:02 ` [PATCH 5/6] rcuscale: Do a proper cleanup if kfree_scale_init() fails Frederic Weisbecker
2024-11-11  9:54   ` Neeraj Upadhyay
2024-11-11 10:53     ` Uladzislau Rezki
2024-11-11 11:22       ` Uladzislau Rezki
2024-11-06 16:02 ` [PATCH 6/6] rcuscale: Remove redundant WARN_ON_ONCE() splat Frederic Weisbecker
2024-11-11 17:35 ` [PATCH 0/6] RCU torture for v6.13 Neeraj Upadhyay

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