[PATCH 5/9] mm/debug: Provide VM_WARN_ON_IRQS_ENABLED()

Sebastian Andrzej Siewior
2022-08-17T16:28:09Z

From: Thomas Gleixner <tglx@linutronix.de>

Some places in the VM code expect interrupts disabled, which is a valid
expectation on non-PREEMPT_RT kernels, but does not hold on RT kernels in
some places because the RT spinlock substitution does not disable
interrupts.

To avoid sprinkling CONFIG_PREEMPT_RT conditionals into those places,
provide VM_WARN_ON_IRQS_ENABLED() which is only enabled when VM_DEBUG=y and
PREEMPT_RT=n.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
include/linux/mmdebug.h | 6 ++++++
lib/Kconfig.debug | 3 +++
2 files changed, 9 insertions(+)

diff --git a/include/linux/mmdebug.h b/include/linux/mmdebug.h
index 15ae78cd28536..b8728d11c9490 100644
--- a/include/linux/mmdebug.h
+++ b/include/linux/mmdebug.h
@@ -94,6 +94,12 @@ void dump_mm(const struct mm_struct *mm);
#define VM_WARN(cond, format...) BUILD_BUG_ON_INVALID(cond)
#endif

+#ifdef CONFIG_DEBUG_VM_IRQSOFF
+#define VM_WARN_ON_IRQS_ENABLED() WARN_ON_ONCE(!irqs_disabled())
+#else
+#define VM_WARN_ON_IRQS_ENABLED() do { } while (0)
+#endif
+
#ifdef CONFIG_DEBUG_VIRTUAL
#define VIRTUAL_BUG_ON(cond) BUG_ON(cond)
#else
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 072e4b289c13e..c96fc6820544c 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -803,6 +803,9 @@ config ARCH_HAS_DEBUG_VM_PGTABLE
An architecture should select this when it can successfully
build and run DEBUG_VM_PGTABLE.

+config DEBUG_VM_IRQSOFF
+ def_bool DEBUG_VM && !PREEMPT_RT
+
config DEBUG_VM
bool "Debug VM"
depends on DEBUG_KERNEL
--
2.37.2