From: Valentin Schneider <valentin.schneider@arm.com>
To: linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, rcu@vger.kernel.org,
linux-rt-users@vger.kernel.org
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Steven Rostedt <rostedt@goodmis.org>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
"Paul E. McKenney" <paulmck@kernel.org>,
Frederic Weisbecker <frederic@kernel.org>,
Josh Triplett <josh@joshtriplett.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Davidlohr Bueso <dave@stgolabs.net>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Joel Fernandes <joel@joelfernandes.org>,
Anshuman Khandual <anshuman.khandual@arm.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Steven Price <steven.price@arm.com>,
Ard Biesheuvel <ardb@kernel.org>
Subject: [PATCH v2 1/4] rcutorture: Don't disable softirqs with preemption disabled when PREEMPT_RT
Date: Sat, 7 Aug 2021 01:58:04 +0100 [thread overview]
Message-ID: <20210807005807.1083943-2-valentin.schneider@arm.com> (raw)
In-Reply-To: <20210807005807.1083943-1-valentin.schneider@arm.com>
Running RCU torture with CONFIG_PREEMPT_RT under v5.14-rc4-rt6 triggers:
[ 8.755472] DEBUG_LOCKS_WARN_ON(this_cpu_read(softirq_ctrl.cnt))
[ 8.755482] WARNING: CPU: 1 PID: 137 at kernel/softirq.c:172 __local_bh_disable_ip (kernel/softirq.c:172 (discriminator 31))
[ 8.755500] Modules linked in:
[ 8.755506] CPU: 1 PID: 137 Comm: rcu_torture_rea Not tainted 5.14.0-rc4-rt6 #171
[ 8.755514] Hardware name: ARM Juno development board (r0) (DT)
[ 8.755518] pstate: 60000005 (nZCv daif -PAN -UAO -TCO BTYPE=--)
[ 8.755622] Call trace:
[ 8.755624] __local_bh_disable_ip (kernel/softirq.c:172 (discriminator 31))
[ 8.755633] rcutorture_one_extend (kernel/rcu/rcutorture.c:1453)
[ 8.755640] rcu_torture_one_read (kernel/rcu/rcutorture.c:1601 kernel/rcu/rcutorture.c:1645)
[ 8.755645] rcu_torture_reader (kernel/rcu/rcutorture.c:1737)
[ 8.755650] kthread (kernel/kthread.c:327)
[ 8.755656] ret_from_fork (arch/arm64/kernel/entry.S:783)
[ 8.755663] irq event stamp: 11959
[ 8.755666] hardirqs last enabled at (11959): __rcu_read_unlock (kernel/rcu/tree_plugin.h:695 kernel/rcu/tree_plugin.h:451)
[ 8.755675] hardirqs last disabled at (11958): __rcu_read_unlock (kernel/rcu/tree_plugin.h:661 kernel/rcu/tree_plugin.h:451)
[ 8.755683] softirqs last enabled at (11950): __local_bh_enable_ip (./arch/arm64/include/asm/irqflags.h:85 kernel/softirq.c:261)
[ 8.755692] softirqs last disabled at (11942): rcutorture_one_extend (./include/linux/bottom_half.h:19 kernel/rcu/rcutorture.c:1441)
Per this warning, softirqs cannot be disabled in a non-preemptible region
under CONFIG_PREEMPT_RT. Adjust RCU torture accordingly.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
---
kernel/rcu/rcutorture.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index eecd1caef71d..4f3db1d3170d 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1548,6 +1548,8 @@ rcutorture_extend_mask(int oldmask, struct torture_random_state *trsp)
* them on non-RT.
*/
if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
+ /* Can't disable bh in atomic context under PREEMPT_RT */
+ mask &= ~(RCUTORTURE_RDR_ATOM_BH | RCUTORTURE_RDR_ATOM_RBH);
/*
* Can't release the outermost rcu lock in an irq disabled
* section without preemption also being disabled, if irqs
--
2.25.1
next prev parent reply other threads:[~2021-08-07 0:58 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-07 0:58 [PATCH v2 0/4] rcu, arm64: PREEMPT_RT fixlets Valentin Schneider
2021-08-07 0:58 ` Valentin Schneider [this message]
2021-08-07 0:58 ` [PATCH v2 2/4] sched: Introduce is_pcpu_safe() Valentin Schneider
2021-08-07 1:42 ` Mike Galbraith
2021-08-08 16:15 ` Valentin Schneider
2021-08-10 12:49 ` Boqun Feng
2021-08-10 13:04 ` Valentin Schneider
2021-08-10 2:42 ` Boqun Feng
2021-08-10 9:26 ` Valentin Schneider
2021-08-07 0:58 ` [PATCH v2 3/4] rcu/nocb: Protect NOCB state via local_lock() under PREEMPT_RT Valentin Schneider
2021-08-07 0:58 ` [PATCH v2 4/4] arm64: mm: Make arch_faults_on_old_pte() check for migratability Valentin Schneider
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