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Date: Mon, 13 Jun 2011 09:56:39 -0400
From: Eric B Munson <emunson@...bm.net>
To: arnd@...db.de
Cc: akpm@...ux-foundation.org, paulmck@...ux.vnet.ibm.com,
mingo@...e.hu, randy.dunlap@...cle.com, josh@...htriplett.org,
linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org,
mgorman@...e.de, linux-mm@...ck.org, dave@...ux.vnet.ibm.com,
Eric B Munson <emunson@...bm.net>
Subject: [PATCH V2] Add debugging boundary check to pfn_to_page
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@...bm.net>
---
Changes from V1:
minimize code duplication with a macro that will do the checking when
configured
include/asm-generic/memory_model.h | 25 ++++++++++++++++++++-----
lib/Kconfig.debug | 9 +++++++++
2 files changed, 29 insertions(+), 5 deletions(-)
diff --git a/include/asm-generic/memory_model.h b/include/asm-generic/memory_model.h
index fb2d63f..7aa83ce 100644
--- a/include/asm-generic/memory_model.h
+++ b/include/asm-generic/memory_model.h
@@ -22,6 +22,16 @@
#endif /* CONFIG_DISCONTIGMEM */
+#ifdef CONFIG_MEMORY_MODEL
+/*
+ * The flags for a page will only be zero if this page is being accessed
+ * outside of node boundaries.
+ */
+#define check_page(__page) WARN_ON(__page->flags == 0)
+#else
+#define check_page(__page) do{}while(0)
+#endif /* CONFIG_MEMORY_MODEL */
+
/*
* supports 3 memory models.
*/
@@ -35,7 +45,9 @@
#define __pfn_to_page(pfn) \
({ unsigned long __pfn = (pfn); \
unsigned long __nid = arch_pfn_to_nid(__pfn); \
- NODE_DATA(__nid)->node_mem_map + arch_local_page_offset(__pfn, __nid);\
+ struct page * __pg = NODE_DATA(__nid)->node_mem_map + arch_local_page_offset(__pfn, __nid);\
+ check_page(__pg); \
+ __pg; \
})
#define __page_to_pfn(pg) \
@@ -52,6 +64,7 @@
#define __page_to_pfn(page) (unsigned long)((page) - vmemmap)
#elif defined(CONFIG_SPARSEMEM)
+
/*
* Note: section's mem_map is encorded to reflect its start_pfn.
* section[i].section_mem_map == mem_map's address - start_pfn;
@@ -62,10 +75,12 @@
(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; \
+#define __pfn_to_page(pfn) \
+({ unsigned long __pfn = (pfn); \
+ struct mem_section *__sec = __pfn_to_section(__pfn); \
+ struct page *__pg = __section_mem_map_addr(__sec) + __pfn; \
+ check_page(__pg); \
+ __pg; \
})
#endif /* CONFIG_FLATMEM/DISCONTIGMEM/SPARSEMEM */
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index dd373c8..7870907 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -777,6 +777,15 @@ config DEBUG_MEMORY_INIT
If unsure, say Y
+config DEBUG_MEMORY_MODEL
+ bool "Debug memory model" if 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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