Bugzilla 36192 showed a problem where pages were being accessed outside of
a node boundary. It would be helpful in diagnosing this kind of problem to
have pfn_to_page complain when a page is accessed outside of the node boundary.
This patch adds a new debug config option which adds a WARN_ON in pfn_to_page
that will complain when pages are accessed outside of the node boundary.
Signed-of-by: Eric B Munson <emunson@xxxxxxxxx>
---
include/asm-generic/memory_model.h | 19 +++++++++++++++----
lib/Kconfig.debug | 10 ++++++++++
2 files changed, 25 insertions(+), 4 deletions(-)
diff --git a/include/asm-generic/memory_model.h b/include/asm-generic/memory_model.h
index fb2d63f..a0f1d19 100644
--- a/include/asm-generic/memory_model.h
+++ b/include/asm-generic/memory_model.h
@@ -62,11 +62,22 @@
(unsigned long)(__pg - __section_mem_map_addr(__nr_to_section(__sec))); \
})
-#define __pfn_to_page(pfn) \
-({ unsigned long __pfn = (pfn); \
- struct mem_section *__sec = __pfn_to_section(__pfn); \
- __section_mem_map_addr(__sec) + __pfn; \
+#ifdef CONFIG_DEBUG_MEMORY_MODEL
+#define __pfn_to_page(pfn) \
+({ unsigned long __pfn = (pfn); \
+ struct mem_section *__sec = __pfn_to_section(__pfn); \
+ struct page *__page = __section_mem_map_addr(__sec) + __pfn; \
+ WARN_ON(__page->flags == 0); \
+ __page; \
})
+#else
+#define __pfn_to_page(pfn) \
+({ unsigned long __pfn = (pfn); \
+ struct mem_section *__sec = __pfn_to_section(__pfn); \
+ __section_mem_map_addr(__sec) + __pfn; \
+})
+#endif /* CONFIG_DEBUG_MEMORY_MODEL */
+
#endif /* CONFIG_FLATMEM/DISCONTIGMEM/SPARSEMEM */
#define page_to_pfn __page_to_pfn
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index dd373c8..d932cbf 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -777,6 +777,16 @@ config DEBUG_MEMORY_INIT
If unsure, say Y
+config DEBUG_MEMORY_MODEL
+ bool "Debug memory model" if SPARSEMEM || DISCONTIGMEM
+ depends on SPARSEMEM || DISCONTIGMEM
+ help
+ Enable this to check that page accesses are done within node
+ boundaries. The check will warn each time a page is requested
+ outside node boundaries.
+
+ If unsure, say N
+
config DEBUG_LIST
bool "Debug linked list manipulation"
depends on DEBUG_KERNEL
--
1.7.4.1
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