From: Joel Fernandes <jfern@kernel.org>
To: linux-kernel@vger.kernel.org,
"Paul E . McKenney" <paulmck@kernel.org>,
Frederic Weisbecker <frederic@kernel.org>,
Neeraj Upadhyay <neeraj.upadhyay@kernel.org>,
Joel Fernandes <jfern@kernel.org>,
Josh Triplett <josh@joshtriplett.org>,
Boqun Feng <boqun@kernel.org>,
Uladzislau Rezki <urezki@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Zqiang <qiang.zhang@linux.dev>, Shuah Khan <shuah@kernel.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Clark Williams <clrkwllms@kernel.org>
Cc: rcu@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>,
linux-kselftest@vger.kernel.org, linux-rt-devel@lists.linux.dev
Subject: [PATCH for-v7.5 12/14] rcutorture: Enable RCU_BOOST where supported
Date: Thu, 12 Nov 2026 19:57:39 -0500 [thread overview]
Message-ID: <20261113005747.2977123-13-jfern@kernel.org> (raw)
In-Reply-To: <20261113005747.2977123-1-jfern@kernel.org>
From: "Paul E. McKenney" <paulmck@kernel.org>
Currently, RCU_BOOST depends on RCU_EXPERT, and is therefore often
disabled in stress-test such as those run by syzbot. This means that if
syzbot runs a test that overloads CPUs on kernels built with PREEMPT_RCU,
RCU CPU stall warnings are not unexpected. What happens is that a
low-priority task in an RCU read-side critical section is preempted,
cannot be priority boosted, and stays that way for more than 21 seconds.
This commit therefore drops RCU_EXPERT from the RCU_BOOST "depends on"
line and removes the prompt, thus directly driving RCU_BOOST from the
kernel configuration so as to enable it anywhere it is supported and
might help.
This commit is also marked experimental because neither Ubuntu, Fedora,
nor CentOS enable RCU_BOOST. This suggests less testing of RCU priority
boosting than one might wish.
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Closes: https://lore.kernel.org/all/20260805122952.6ae38af69a0457779cb44359@linux-foundation.org/
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Joel Fernandes <jfern@kernel.org>
---
kernel/rcu/Kconfig | 10 ++++------
tools/testing/selftests/rcutorture/configs/rcu/NOCB01 | 1 -
tools/testing/selftests/rcutorture/configs/rcu/NOCB02 | 1 -
tools/testing/selftests/rcutorture/configs/rcu/TREE01 | 1 -
tools/testing/selftests/rcutorture/configs/rcu/TREE02 | 1 -
tools/testing/selftests/rcutorture/configs/rcu/TREE08 | 1 -
.../testing/selftests/rcutorture/configs/rcuscale/TINY | 1 -
.../selftests/rcutorture/configs/rcuscale/TRACE01 | 1 -
.../testing/selftests/rcutorture/configs/rcuscale/TREE | 1 -
.../selftests/rcutorture/configs/rcuscale/TREE54 | 1 -
.../selftests/rcutorture/configs/refscale/NOPREEMPT | 1 -
.../selftests/rcutorture/configs/refscale/PREEMPT | 1 -
.../testing/selftests/rcutorture/configs/refscale/TINY | 1 -
13 files changed, 4 insertions(+), 18 deletions(-)
diff --git a/kernel/rcu/Kconfig b/kernel/rcu/Kconfig
index b6d3597758fc..2d0132e0a90f 100644
--- a/kernel/rcu/Kconfig
+++ b/kernel/rcu/Kconfig
@@ -238,17 +238,15 @@ config RCU_FANOUT_LEAF
Take the default if unsure.
config RCU_BOOST
- bool "Enable RCU priority boosting"
- depends on (RT_MUTEXES && PREEMPT_RCU && RCU_EXPERT) || PREEMPT_RT
- default y if PREEMPT_RT
+ bool
+ default y if (RT_MUTEXES && PREEMPT_RCU) || PREEMPT_RT
help
This option boosts the priority of preempted RCU readers that
block the current preemptible RCU grace period for too long.
This option also prevents heavy loads from blocking RCU
- callback invocation.
+ callback invocation. It is now automatically enabled in
+ any kernel that can benefit from it and that can support it.
- Say Y here if you are working with real-time apps or heavy loads
- Say N here if you are unsure.
config RCU_BOOST_DELAY
int "Milliseconds to delay boosting after RCU grace-period start"
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/NOCB01 b/tools/testing/selftests/rcutorture/configs/rcu/NOCB01
index bbe6d28210ab..91ca7e8b5725 100644
--- a/tools/testing/selftests/rcutorture/configs/rcu/NOCB01
+++ b/tools/testing/selftests/rcutorture/configs/rcu/NOCB01
@@ -14,7 +14,6 @@ CONFIG_RCU_FANOUT_LEAF=2
CONFIG_RCU_NOCB_CPU=y
CONFIG_DEBUG_LOCK_ALLOC=n
CONFIG_PROVE_LOCKING=n
-CONFIG_RCU_BOOST=n
CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
CONFIG_RCU_EXPERT=y
CONFIG_RCU_EQS_DEBUG=y
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/NOCB02 b/tools/testing/selftests/rcutorture/configs/rcu/NOCB02
index 4c2b8cd6d8fd..ed3f3f7b29e7 100644
--- a/tools/testing/selftests/rcutorture/configs/rcu/NOCB02
+++ b/tools/testing/selftests/rcutorture/configs/rcu/NOCB02
@@ -14,7 +14,6 @@ CONFIG_RCU_FANOUT_LEAF=2
CONFIG_RCU_NOCB_CPU=y
CONFIG_DEBUG_LOCK_ALLOC=n
CONFIG_PROVE_LOCKING=n
-CONFIG_RCU_BOOST=n
CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
CONFIG_RCU_EXPERT=y
CONFIG_RCU_EQS_DEBUG=y
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TREE01 b/tools/testing/selftests/rcutorture/configs/rcu/TREE01
index 54b1600c7eb5..be5bf69a1b60 100644
--- a/tools/testing/selftests/rcutorture/configs/rcu/TREE01
+++ b/tools/testing/selftests/rcutorture/configs/rcu/TREE01
@@ -10,6 +10,5 @@ CONFIG_RCU_TRACE=y
CONFIG_HOTPLUG_CPU=y
CONFIG_RCU_NOCB_CPU=y
CONFIG_DEBUG_LOCK_ALLOC=n
-CONFIG_RCU_BOOST=n
CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
CONFIG_RCU_EXPERT=y
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TREE02 b/tools/testing/selftests/rcutorture/configs/rcu/TREE02
index 2871ee599891..36b9228ae703 100644
--- a/tools/testing/selftests/rcutorture/configs/rcu/TREE02
+++ b/tools/testing/selftests/rcutorture/configs/rcu/TREE02
@@ -13,7 +13,6 @@ CONFIG_RCU_FANOUT_LEAF=3
CONFIG_RCU_NOCB_CPU=n
CONFIG_DEBUG_LOCK_ALLOC=y
CONFIG_PROVE_LOCKING=n
-CONFIG_RCU_BOOST=n
CONFIG_RCU_EXPERT=y
CONFIG_DEBUG_OBJECTS=y
CONFIG_DEBUG_OBJECTS_RCU_HEAD=y
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TREE08 b/tools/testing/selftests/rcutorture/configs/rcu/TREE08
index 8b561355b9ef..ad7d7f873e1e 100644
--- a/tools/testing/selftests/rcutorture/configs/rcu/TREE08
+++ b/tools/testing/selftests/rcutorture/configs/rcu/TREE08
@@ -13,7 +13,6 @@ CONFIG_RCU_FANOUT_LEAF=2
CONFIG_RCU_NOCB_CPU=y
CONFIG_DEBUG_LOCK_ALLOC=n
CONFIG_PROVE_LOCKING=n
-CONFIG_RCU_BOOST=n
CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
CONFIG_RCU_EXPERT=y
CONFIG_RCU_EQS_DEBUG=y
diff --git a/tools/testing/selftests/rcutorture/configs/rcuscale/TINY b/tools/testing/selftests/rcutorture/configs/rcuscale/TINY
index c1a7d38823fb..f611b69f1189 100644
--- a/tools/testing/selftests/rcutorture/configs/rcuscale/TINY
+++ b/tools/testing/selftests/rcutorture/configs/rcuscale/TINY
@@ -11,7 +11,6 @@ CONFIG_NO_HZ_FULL=n
CONFIG_RCU_NOCB_CPU=n
CONFIG_DEBUG_LOCK_ALLOC=n
CONFIG_PROVE_LOCKING=n
-CONFIG_RCU_BOOST=n
CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
CONFIG_RCU_EXPERT=y
CONFIG_RCU_TRACE=y
diff --git a/tools/testing/selftests/rcutorture/configs/rcuscale/TRACE01 b/tools/testing/selftests/rcutorture/configs/rcuscale/TRACE01
index f3f1368b8386..69f5764159df 100644
--- a/tools/testing/selftests/rcutorture/configs/rcuscale/TRACE01
+++ b/tools/testing/selftests/rcutorture/configs/rcuscale/TRACE01
@@ -11,7 +11,6 @@ CONFIG_NO_HZ_FULL=n
CONFIG_RCU_NOCB_CPU=n
CONFIG_DEBUG_LOCK_ALLOC=n
CONFIG_PROVE_LOCKING=n
-CONFIG_RCU_BOOST=n
CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
CONFIG_RCU_EXPERT=y
CONFIG_RCU_TRACE=y
diff --git a/tools/testing/selftests/rcutorture/configs/rcuscale/TREE b/tools/testing/selftests/rcutorture/configs/rcuscale/TREE
index b10706fd03a4..5122cf08d5db 100644
--- a/tools/testing/selftests/rcutorture/configs/rcuscale/TREE
+++ b/tools/testing/selftests/rcutorture/configs/rcuscale/TREE
@@ -12,7 +12,6 @@ CONFIG_HIBERNATION=n
CONFIG_RCU_NOCB_CPU=n
CONFIG_DEBUG_LOCK_ALLOC=n
CONFIG_PROVE_LOCKING=n
-CONFIG_RCU_BOOST=n
CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
CONFIG_RCU_EXPERT=y
CONFIG_RCU_TRACE=y
diff --git a/tools/testing/selftests/rcutorture/configs/rcuscale/TREE54 b/tools/testing/selftests/rcutorture/configs/rcuscale/TREE54
index 9f83e5372796..08d30edb3b99 100644
--- a/tools/testing/selftests/rcutorture/configs/rcuscale/TREE54
+++ b/tools/testing/selftests/rcutorture/configs/rcuscale/TREE54
@@ -15,7 +15,6 @@ CONFIG_RCU_FANOUT_LEAF=2
CONFIG_RCU_NOCB_CPU=n
CONFIG_DEBUG_LOCK_ALLOC=n
CONFIG_PROVE_LOCKING=n
-CONFIG_RCU_BOOST=n
CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
CONFIG_RCU_EXPERT=y
CONFIG_RCU_TRACE=y
diff --git a/tools/testing/selftests/rcutorture/configs/refscale/NOPREEMPT b/tools/testing/selftests/rcutorture/configs/refscale/NOPREEMPT
index 1f215e17cbae..3e7d7793acc7 100644
--- a/tools/testing/selftests/rcutorture/configs/refscale/NOPREEMPT
+++ b/tools/testing/selftests/rcutorture/configs/refscale/NOPREEMPT
@@ -14,7 +14,6 @@ CONFIG_HIBERNATION=n
CONFIG_RCU_NOCB_CPU=n
CONFIG_DEBUG_LOCK_ALLOC=n
CONFIG_PROVE_LOCKING=n
-CONFIG_RCU_BOOST=n
CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
CONFIG_RCU_EXPERT=y
CONFIG_KPROBES=n
diff --git a/tools/testing/selftests/rcutorture/configs/refscale/PREEMPT b/tools/testing/selftests/rcutorture/configs/refscale/PREEMPT
index 52e3ef674056..feed29cf043f 100644
--- a/tools/testing/selftests/rcutorture/configs/refscale/PREEMPT
+++ b/tools/testing/selftests/rcutorture/configs/refscale/PREEMPT
@@ -12,6 +12,5 @@ CONFIG_HIBERNATION=n
CONFIG_RCU_NOCB_CPU=n
CONFIG_DEBUG_LOCK_ALLOC=n
CONFIG_PROVE_LOCKING=n
-CONFIG_RCU_BOOST=n
CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
CONFIG_RCU_EXPERT=y
diff --git a/tools/testing/selftests/rcutorture/configs/refscale/TINY b/tools/testing/selftests/rcutorture/configs/refscale/TINY
index 9a11b578ff34..b67ea7a9128b 100644
--- a/tools/testing/selftests/rcutorture/configs/refscale/TINY
+++ b/tools/testing/selftests/rcutorture/configs/refscale/TINY
@@ -14,7 +14,6 @@ CONFIG_HIBERNATION=n
CONFIG_RCU_NOCB_CPU=n
CONFIG_DEBUG_LOCK_ALLOC=n
CONFIG_PROVE_LOCKING=n
-CONFIG_RCU_BOOST=n
CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
CONFIG_RCU_EXPERT=y
CONFIG_KPROBES=n
--
2.54.0
next prev parent reply other threads:[~2026-11-13 0:58 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-13 0:57 [PATCH for-v7.5 00/14] RCU tests patches for v7.5 Joel Fernandes
2026-11-13 0:57 ` [PATCH for-v7.5 01/14] Documentation/litmus-tests: Add SRCU fastpath anchor-before-scan test Joel Fernandes
2026-11-13 0:57 ` [PATCH for-v7.5 02/14] Documentation/litmus-tests: Add SRCU fastpath scan-before-anchor test Joel Fernandes
2026-11-13 0:57 ` [PATCH for-v7.5 03/14] kasan: Avoid an unrelated RCU warning in the callback test Joel Fernandes
2026-11-13 0:57 ` [PATCH for-v7.5 04/14] rcutorture: Fix busted_srcud crash on module unload Joel Fernandes
2026-11-13 0:57 ` [PATCH for-v7.5 05/14] rcutorture: Fix suspicious rcu_dereference_check() usage for trivial-preempt Joel Fernandes
2026-11-13 0:57 ` [PATCH for-v7.5 06/14] rcutorture: Make tasks-tracing support duplicate call testing Joel Fernandes
2026-11-13 0:57 ` [PATCH for-v7.5 07/14] rcutorture: Avoid create fwd_prog_tasks for tasks-rude and srcu-atomic Joel Fernandes
2026-11-13 0:57 ` [PATCH for-v7.5 08/14] rcuscale: Consolidate per-writer arrays into struct writer_state Joel Fernandes
2026-11-13 0:57 ` [PATCH for-v7.5 09/14] rcuscale: Add srcua scale type Joel Fernandes
2026-11-13 0:57 ` [PATCH for-v7.5 10/14] scftorture: Reject empty workloads before starting helpers Joel Fernandes
2026-11-13 0:57 ` [PATCH for-v7.5 11/14] scftorture: Protect the initial affinity check from hotplug Joel Fernandes
2026-11-13 0:57 ` Joel Fernandes [this message]
2026-11-13 0:57 ` [PATCH for-v7.5 13/14] rcutorture: Disable RCU priority boost testing on non-TREE03 scenarios Joel Fernandes
2026-11-13 0:57 ` [PATCH for-v7.5 14/14] torture: Forgive SMT-control failures in CPU-hotplug testing Joel Fernandes
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