Merge branch 'kmemleak' of git://linux-arm.org/linux-2.6

* 'kmemleak' of git://linux-arm.org/linux-2.6:
  kmemleak: fix kconfig for crc32 build error
  kmemleak: Reduce the false positives by checking for modified objects
  kmemleak: Show the age of an unreferenced object
  kmemleak: Release the object lock before calling put_object()
  kmemleak: Scan the _ftrace_events section in modules
  kmemleak: Simplify the kmemleak_scan_area() function prototype
  kmemleak: Do not use off-slab management with SLAB_NOLEAKTRACE

include/linux/kmemleak.h

@@ -32,8 +32,7 @@ extern void kmemleak_padding(const void *ptr, unsigned long offset,
 			     size_t size) __ref;
 extern void kmemleak_not_leak(const void *ptr) __ref;
 extern void kmemleak_ignore(const void *ptr) __ref;
-extern void kmemleak_scan_area(const void *ptr, unsigned long offset,
-			       size_t length, gfp_t gfp) __ref;
+extern void kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp) __ref;
 extern void kmemleak_no_scan(const void *ptr) __ref;
 
 static inline void kmemleak_alloc_recursive(const void *ptr, size_t size,
@@ -84,8 +83,7 @@ static inline void kmemleak_not_leak(const void *ptr)
 static inline void kmemleak_ignore(const void *ptr)
 {
 }
-static inline void kmemleak_scan_area(const void *ptr, unsigned long offset,
-				      size_t length, gfp_t gfp)
+static inline void kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp)
 {
 }
 static inline void kmemleak_erase(void **ptr)

kernel/module.c

@@ -1910,9 +1910,7 @@ static void kmemleak_load_module(struct module *mod, Elf_Ehdr *hdr,
 	unsigned int i;
 
 	/* only scan the sections containing data */
-	kmemleak_scan_area(mod->module_core, (unsigned long)mod -
-			   (unsigned long)mod->module_core,
-			   sizeof(struct module), GFP_KERNEL);
+	kmemleak_scan_area(mod, sizeof(struct module), GFP_KERNEL);
 
 	for (i = 1; i < hdr->e_shnum; i++) {
 		if (!(sechdrs[i].sh_flags & SHF_ALLOC))
@@ -1921,8 +1919,7 @@ static void kmemleak_load_module(struct module *mod, Elf_Ehdr *hdr,
 		    && strncmp(secstrings + sechdrs[i].sh_name, ".bss", 4) != 0)
 			continue;
 
-		kmemleak_scan_area(mod->module_core, sechdrs[i].sh_addr -
-				   (unsigned long)mod->module_core,
+		kmemleak_scan_area((void *)sechdrs[i].sh_addr,
 				   sechdrs[i].sh_size, GFP_KERNEL);
 	}
 }
@@ -2250,6 +2247,12 @@ static noinline struct module *load_module(void __user *umod,
 					 "_ftrace_events",
 					 sizeof(*mod->trace_events),
 					 &mod->num_trace_events);
+	/*
+	 * This section contains pointers to allocated objects in the trace
+	 * code and not scanning it leads to false positives.
+	 */
+	kmemleak_scan_area(mod->trace_events, sizeof(*mod->trace_events) *
+			   mod->num_trace_events, GFP_KERNEL);
 #endif
 #ifdef CONFIG_FTRACE_MCOUNT_RECORD
 	/* sechdrs[0].sh_size is always zero */

lib/Kconfig.debug

@@ -360,6 +360,7 @@ config DEBUG_KMEMLEAK
 	select DEBUG_FS if SYSFS
 	select STACKTRACE if STACKTRACE_SUPPORT
 	select KALLSYMS
+	select CRC32
 	help
 	  Say Y here if you want to enable the memory leak
 	  detector. The memory allocation/freeing is traced in a way

mm/slab.c

@@ -2275,9 +2275,11 @@ kmem_cache_create (const char *name, size_t size, size_t align,
 	/*
 	 * Determine if the slab management is 'on' or 'off' slab.
 	 * (bootstrapping cannot cope with offslab caches so don't do
-	 * it too early on.)
+	 * it too early on. Always use on-slab management when
+	 * SLAB_NOLEAKTRACE to avoid recursive calls into kmemleak)
 	 */
-	if ((size >= (PAGE_SIZE >> 3)) && !slab_early_init)
+	if ((size >= (PAGE_SIZE >> 3)) && !slab_early_init &&
+	    !(flags & SLAB_NOLEAKTRACE))
 		/*
 		 * Size is large, assume best to place the slab management obj
 		 * off-slab (should allow better packing of objs).
@@ -2596,8 +2598,8 @@ static struct slab *alloc_slabmgmt(struct kmem_cache *cachep, void *objp,
 		 * kmemleak does not treat the ->s_mem pointer as a reference
 		 * to the object. Otherwise we will not report the leak.
 		 */
-		kmemleak_scan_area(slabp, offsetof(struct slab, list),
-				   sizeof(struct list_head), local_flags);
+		kmemleak_scan_area(&slabp->list, sizeof(struct list_head),
+				   local_flags);
 		if (!slabp)
 			return NULL;
 	} else {