kmemleak: Add support for memory hotplug

Currently, kmemleak is not supported with memory hotplug. This has been discussed before[1] but never really went anywhere. Catalin's other suggestion was to add callbacks for memory hotplug but given there is now a nice lock_memory_hotplug function, this seems like the right place to call it. Down the road call backs could be added but this should hopefully enable hotplug to be used with kmemleak.

-Laura

[1] https://lkml.org/lkml/2010/3/22/395

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Ensure that memory hotplug can co-exist with kmemleak by taking the hotplug lock before scanning the memory banks.

---
 lib/Kconfig.debug |    2 +-
 mm/kmemleak.c     |    6 ++++--
 2 files changed, 5 insertions(+), 3 deletions(-)

index c6b006a..6a9e368 100644
@@ -413,7 +413,7 @@ config SLUB_STATS
 
 config DEBUG_KMEMLEAK
 	bool "Kernel memory leak detector"
-	depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
+	depends on DEBUG_KERNEL && EXPERIMENTAL && \
 		(X86 || ARM || PPC || MIPS || S390 || SPARC64 || SUPERH || MICROBLAZE || TILE)
 
 	select DEBUG_FS

index aacee45..4facb03 100644
@@ -100,6 +100,7 @@
 
 #include <linux/kmemcheck.h>
 #include <linux/kmemleak.h>
+#include <linux/memory_hotplug.h>
 
 /*
  * Kmemleak configuration and common defines.

@@ -1220,9 +1221,9 @@ static void kmemleak_scan(void)
 #endif
 
 	/*
-	 * Struct page scanning for each node. The code below is not yet safe
-	 * with MEMORY_HOTPLUG.
+	 * Struct page scanning for each node.
 	 */
+	lock_memory_hotplug();
 	for_each_online_node(i) {
 		pg_data_t *pgdat = NODE_DATA(i);
 		unsigned long start_pfn = pgdat->node_start_pfn;

@@ -1241,6 +1242,7 @@ static void kmemleak_scan(void)
 			scan_block(page, page + 1, NULL, 1);
 		}
 	}
+	unlock_memory_hotplug();
 
 	/*
 	 * Scanning the task stacks (may introduce false negatives).

1.7.6

Thanks, the patch looks fine to me. I'll add it to my kmemleak branch for the next merging window.

Catalin

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