CONFIG_KMAP_LOCAL can be enabled by x86/32bit even if CONFIG_HIGHMEM is not
enabled for temporary MMIO space mappings.
Provide it as a seperate config option which depends on CONFIG_KMAP_LOCAL
and let CONFIG_DEBUG_HIGHMEM select it.
This won't increase the debug coverage of this significantly but it paves
the way to do so.
Signed-off-by: Thomas Gleixner <t...@linutronix.de>
---
V4: New patch
---
include/asm-generic/kmap_size.h | 2 +-
lib/Kconfig.debug | 8 ++++++++
mm/highmem.c | 4 ++--
3 files changed, 11 insertions(+), 3 deletions(-)
--- a/include/asm-generic/kmap_size.h
+++ b/include/asm-generic/kmap_size.h
@@ -3,7 +3,7 @@
#define _ASM_GENERIC_KMAP_SIZE_H
/* For debug this provides guard pages between the maps */
-#ifdef CONFIG_DEBUG_HIGHMEM
+#ifdef CONFIG_DEBUG_KMAP_LOCAL
# define KM_MAX_IDX 33
#else
# define KM_MAX_IDX 16
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -849,9 +849,17 @@ config DEBUG_PER_CPU_MAPS
Say N if unsure.
+config DEBUG_KMAP_LOCAL
+ bool "Debug kmap_local temporary mappings"
+ depends on DEBUG_KERNEL && KMAP_LOCAL
+ help
+ This option enables additional error checking for the kmap_local
+ infrastructure. Disable for production use.
+
config DEBUG_HIGHMEM
bool "Highmem debugging"
depends on DEBUG_KERNEL && HIGHMEM
+ select DEBUG_KMAP_LOCAL
help
This option enables additional error checking for high memory
systems. Disable for production systems.
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -368,10 +368,10 @@ EXPORT_SYMBOL(kunmap_high);
static DEFINE_PER_CPU(int, __kmap_local_idx);
/*
- * With DEBUG_HIGHMEM the stack depth is doubled and every second
+ * With DEBUG_KMAP_LOCAL the stack depth is doubled and every second
* slot is unused which acts as a guard page
*/
-#ifdef CONFIG_DEBUG_HIGHMEM
+#ifdef CONFIG_DEBUG_KMAP_LOCAL
# define KM_INCR 2
#else
# define KM_INCR 1
