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From: Thomas Gleixner <tglx@linutronix.de>
Date: Thu, 25 Aug 2022 18:41:27 +0200
Subject: [PATCH 4/8] mm/debug: Provide VM_WARN_ON_IRQS_ENABLED()
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.0/older/patches-6.0-rt11.tar.xz
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>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220825164131.402717-5-bigeasy@linutronix.de
---
include/linux/mmdebug.h | 6 ++++++
lib/Kconfig.debug | 3 +++
2 files changed, 9 insertions(+)
--- 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
--- 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
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