[PATCH 11/33] cpuset: Provide lockdep check for cpuset lock held

Frederic Weisbecker
2025-10-13T20:33:25Z

cpuset modifies partitions, including isolated, while holding the cpuset
mutex.

This means that holding the cpuset mutex is safe to synchronize against
housekeeping cpumask changes.

Provide a lockdep check to validate that.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
include/linux/cpuset.h | 2 ++
kernel/cgroup/cpuset.c | 7 +++++++
2 files changed, 9 insertions(+)

diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
index 2ddb256187b5..051d36fec578 100644
--- a/include/linux/cpuset.h
+++ b/include/linux/cpuset.h
@@ -18,6 +18,8 @@
#include <linux/mmu_context.h>
#include <linux/jump_label.h>

+extern bool lockdep_is_cpuset_held(void);
+
#ifdef CONFIG_CPUSETS

/*
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 8595f1eadf23..aa1ac7bcf2ea 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -279,6 +279,13 @@ void cpuset_full_unlock(void)
cpus_read_unlock();
}

+#ifdef CONFIG_LOCKDEP
+bool lockdep_is_cpuset_held(void)
+{
+ return lockdep_is_held(&cpuset_mutex);
+}
+#endif
+
static DEFINE_SPINLOCK(callback_lock);

void cpuset_callback_lock_irq(void)
--
2.51.0