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From:   Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To:     linux-kernel@vger.kernel.org
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Matthew Wilcox <willy@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: [PATCH 5/9] mm/debug: Provide VM_WARN_ON_IRQS_ENABLED()
Date:   Wed, 17 Aug 2022 18:26:59 +0200
Message-Id: <20220817162703.728679-6-bigeasy@linutronix.de>
In-Reply-To: <20220817162703.728679-1-bigeasy@linutronix.de>
References: <20220817162703.728679-1-bigeasy@linutronix.de>
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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=3Dy a=
nd
PREEMPT_RT=3Dn.

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
=20
+#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.
=20
+config DEBUG_VM_IRQSOFF
+	def_bool DEBUG_VM && !PREEMPT_RT
+
 config DEBUG_VM
 	bool "Debug VM"
 	depends on DEBUG_KERNEL
--=20
2.37.2