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

* 'for-linus' of git://linux-arm.org/linux-2.6:
  kmemleak: Add the corresponding MAINTAINERS entry
  kmemleak: Simple testing module for kmemleak
  kmemleak: Enable the building of the memory leak detector
  kmemleak: Remove some of the kmemleak false positives
  kmemleak: Add modules support
  kmemleak: Add kmemleak_alloc callback from alloc_large_system_hash
  kmemleak: Add the vmalloc memory allocation/freeing hooks
  kmemleak: Add the slub memory allocation/freeing hooks
  kmemleak: Add the slob memory allocation/freeing hooks
  kmemleak: Add the slab memory allocation/freeing hooks
  kmemleak: Add documentation on the memory leak detector
  kmemleak: Add the base support

Manual conflict resolution (with the slab/earlyboot changes) in:
	drivers/char/vt.c
	init/main.c
	mm/slab.c

Documentation/kernel-parameters.txt

@@ -1083,6 +1083,10 @@ and is between 256 and 4096 characters. It is defined in the file
 			Configure the RouterBoard 532 series on-chip
 			Ethernet adapter MAC address.
 
+	kmemleak=	[KNL] Boot-time kmemleak enable/disable
+			Valid arguments: on, off
+			Default: on
+
 	kstack=N	[X86] Print N words from the kernel stack
 			in oops dumps.
 

Documentation/kmemleak.txt

+Kernel Memory Leak Detector
+===========================
+
+Introduction
+------------
+
+Kmemleak provides a way of detecting possible kernel memory leaks in a
+way similar to a tracing garbage collector
+(http://en.wikipedia.org/wiki/Garbage_collection_%28computer_science%29#Tracing_garbage_collectors),
+with the difference that the orphan objects are not freed but only
+reported via /sys/kernel/debug/kmemleak. A similar method is used by the
+Valgrind tool (memcheck --leak-check) to detect the memory leaks in
+user-space applications.
+
+Usage
+-----
+
+CONFIG_DEBUG_KMEMLEAK in "Kernel hacking" has to be enabled. A kernel
+thread scans the memory every 10 minutes (by default) and prints any new
+unreferenced objects found. To trigger an intermediate scan and display
+all the possible memory leaks:
+
+  # mount -t debugfs nodev /sys/kernel/debug/
+  # cat /sys/kernel/debug/kmemleak
+
+Note that the orphan objects are listed in the order they were allocated
+and one object at the beginning of the list may cause other subsequent
+objects to be reported as orphan.
+
+Memory scanning parameters can be modified at run-time by writing to the
+/sys/kernel/debug/kmemleak file. The following parameters are supported:
+
+  off		- disable kmemleak (irreversible)
+  stack=on	- enable the task stacks scanning
+  stack=off	- disable the tasks stacks scanning
+  scan=on	- start the automatic memory scanning thread
+  scan=off	- stop the automatic memory scanning thread
+  scan=<secs>	- set the automatic memory scanning period in seconds (0
+		  to disable it)
+
+Kmemleak can also be disabled at boot-time by passing "kmemleak=off" on
+the kernel command line.
+
+Basic Algorithm
+---------------
+
+The memory allocations via kmalloc, vmalloc, kmem_cache_alloc and
+friends are traced and the pointers, together with additional
+information like size and stack trace, are stored in a prio search tree.
+The corresponding freeing function calls are tracked and the pointers
+removed from the kmemleak data structures.
+
+An allocated block of memory is considered orphan if no pointer to its
+start address or to any location inside the block can be found by
+scanning the memory (including saved registers). This means that there
+might be no way for the kernel to pass the address of the allocated
+block to a freeing function and therefore the block is considered a
+memory leak.
+
+The scanning algorithm steps:
+
+  1. mark all objects as white (remaining white objects will later be
+     considered orphan)
+  2. scan the memory starting with the data section and stacks, checking
+     the values against the addresses stored in the prio search tree. If
+     a pointer to a white object is found, the object is added to the
+     gray list
+  3. scan the gray objects for matching addresses (some white objects
+     can become gray and added at the end of the gray list) until the
+     gray set is finished
+  4. the remaining white objects are considered orphan and reported via
+     /sys/kernel/debug/kmemleak
+
+Some allocated memory blocks have pointers stored in the kernel's
+internal data structures and they cannot be detected as orphans. To
+avoid this, kmemleak can also store the number of values pointing to an
+address inside the block address range that need to be found so that the
+block is not considered a leak. One example is __vmalloc().
+
+Kmemleak API
+------------
+
+See the include/linux/kmemleak.h header for the functions prototype.
+
+kmemleak_init		 - initialize kmemleak
+kmemleak_alloc		 - notify of a memory block allocation
+kmemleak_free		 - notify of a memory block freeing
+kmemleak_not_leak	 - mark an object as not a leak
+kmemleak_ignore		 - do not scan or report an object as leak
+kmemleak_scan_area	 - add scan areas inside a memory block
+kmemleak_no_scan	 - do not scan a memory block
+kmemleak_erase		 - erase an old value in a pointer variable
+kmemleak_alloc_recursive - as kmemleak_alloc but checks the recursiveness
+kmemleak_free_recursive	 - as kmemleak_free but checks the recursiveness
+
+Dealing with false positives/negatives
+--------------------------------------
+
+The false negatives are real memory leaks (orphan objects) but not
+reported by kmemleak because values found during the memory scanning
+point to such objects. To reduce the number of false negatives, kmemleak
+provides the kmemleak_ignore, kmemleak_scan_area, kmemleak_no_scan and
+kmemleak_erase functions (see above). The task stacks also increase the
+amount of false negatives and their scanning is not enabled by default.
+
+The false positives are objects wrongly reported as being memory leaks
+(orphan). For objects known not to be leaks, kmemleak provides the
+kmemleak_not_leak function. The kmemleak_ignore could also be used if
+the memory block is known not to contain other pointers and it will no
+longer be scanned.
+
+Some of the reported leaks are only transient, especially on SMP
+systems, because of pointers temporarily stored in CPU registers or
+stacks. Kmemleak defines MSECS_MIN_AGE (defaulting to 1000) representing
+the minimum age of an object to be reported as a memory leak.
+
+Limitations and Drawbacks
+-------------------------
+
+The main drawback is the reduced performance of memory allocation and
+freeing. To avoid other penalties, the memory scanning is only performed
+when the /sys/kernel/debug/kmemleak file is read. Anyway, this tool is
+intended for debugging purposes where the performance might not be the
+most important requirement.
+
+To keep the algorithm simple, kmemleak scans for values pointing to any
+address inside a block's address range. This may lead to an increased
+number of false negatives. However, it is likely that a real memory leak
+will eventually become visible.
+
+Another source of false negatives is the data stored in non-pointer
+values. In a future version, kmemleak could only scan the pointer
+members in the allocated structures. This feature would solve many of
+the false negative cases described above.
+
+The tool can report false positives. These are cases where an allocated
+block doesn't need to be freed (some cases in the init_call functions),
+the pointer is calculated by other methods than the usual container_of
+macro or the pointer is stored in a location not scanned by kmemleak.
+
+Page allocations and ioremap are not tracked. Only the ARM and x86
+architectures are currently supported.

MAINTAINERS

@@ -3370,6 +3370,12 @@ F:	Documentation/trace/kmemtrace.txt
 F:	include/trace/kmemtrace.h
 F:	kernel/trace/kmemtrace.c
 
+KMEMLEAK
+P:	Catalin Marinas
+M:	catalin.marinas@arm.com
+L:	linux-kernel@vger.kernel.org
+S:	Maintained
+
 KPROBES
 P:	Ananth N Mavinakayanahalli
 M:	ananth@in.ibm.com

drivers/char/vt.c

@@ -103,6 +103,7 @@
 #include <linux/io.h>
 #include <asm/system.h>
 #include <linux/uaccess.h>
+#include <linux/kmemleak.h>
 
 #define MAX_NR_CON_DRIVER 16
 

fs/block_dev.c

@@ -25,6 +25,7 @@
 #include <linux/uio.h>
 #include <linux/namei.h>
 #include <linux/log2.h>
+#include <linux/kmemleak.h>
 #include <asm/uaccess.h>
 #include "internal.h"
 
@@ -492,6 +493,11 @@ void __init bdev_cache_init(void)
 	bd_mnt = kern_mount(&bd_type);
 	if (IS_ERR(bd_mnt))
 		panic("Cannot create bdev pseudo-fs");
+	/*
+	 * This vfsmount structure is only used to obtain the
+	 * blockdev_superblock, so tell kmemleak not to report it.
+	 */
+	kmemleak_not_leak(bd_mnt);
 	blockdev_superblock = bd_mnt->mnt_sb;	/* For writeback */
 }
 

include/linux/kmemleak.h

+/*
+ * include/linux/kmemleak.h
+ *
+ * Copyright (C) 2008 ARM Limited
+ * Written by Catalin Marinas <catalin.marinas@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#ifndef __KMEMLEAK_H
+#define __KMEMLEAK_H
+
+#ifdef CONFIG_DEBUG_KMEMLEAK
+
+extern void kmemleak_init(void);
+extern void kmemleak_alloc(const void *ptr, size_t size, int min_count,
+			   gfp_t gfp);
+extern void kmemleak_free(const void *ptr);
+extern void kmemleak_padding(const void *ptr, unsigned long offset,
+			     size_t size);
+extern void kmemleak_not_leak(const void *ptr);
+extern void kmemleak_ignore(const void *ptr);
+extern void kmemleak_scan_area(const void *ptr, unsigned long offset,
+			       size_t length, gfp_t gfp);
+extern void kmemleak_no_scan(const void *ptr);
+
+static inline void kmemleak_alloc_recursive(const void *ptr, size_t size,
+					    int min_count, unsigned long flags,
+					    gfp_t gfp)
+{
+	if (!(flags & SLAB_NOLEAKTRACE))
+		kmemleak_alloc(ptr, size, min_count, gfp);
+}
+
+static inline void kmemleak_free_recursive(const void *ptr, unsigned long flags)
+{
+	if (!(flags & SLAB_NOLEAKTRACE))
+		kmemleak_free(ptr);
+}
+
+static inline void kmemleak_erase(void **ptr)
+{
+	*ptr = NULL;
+}
+
+#else
+
+static inline void kmemleak_init(void)
+{
+}
+static inline void kmemleak_alloc(const void *ptr, size_t size, int min_count,
+				  gfp_t gfp)
+{
+}
+static inline void kmemleak_alloc_recursive(const void *ptr, size_t size,
+					    int min_count, unsigned long flags,
+					    gfp_t gfp)
+{
+}
+static inline void kmemleak_free(const void *ptr)
+{
+}
+static inline void kmemleak_free_recursive(const void *ptr, unsigned long flags)
+{
+}
+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_erase(void **ptr)
+{
+}
+static inline void kmemleak_no_scan(const void *ptr)
+{
+}
+
+#endif	/* CONFIG_DEBUG_KMEMLEAK */
+
+#endif	/* __KMEMLEAK_H */

include/linux/percpu.h

@@ -86,7 +86,12 @@ struct percpu_data {
 	void *ptrs[1];
 };
 
+/* pointer disguising messes up the kmemleak objects tracking */
+#ifndef CONFIG_DEBUG_KMEMLEAK
 #define __percpu_disguise(pdata) (struct percpu_data *)~(unsigned long)(pdata)
+#else
+#define __percpu_disguise(pdata) (struct percpu_data *)(pdata)
+#endif
 
 #define per_cpu_ptr(ptr, cpu)						\
 ({									\

include/linux/slab.h

@@ -62,6 +62,8 @@
 # define SLAB_DEBUG_OBJECTS	0x00000000UL
 #endif
 
+#define SLAB_NOLEAKTRACE	0x00800000UL	/* Avoid kmemleak tracing */
+
 /* The following flags affect the page allocator grouping pages by mobility */
 #define SLAB_RECLAIM_ACCOUNT	0x00020000UL		/* Objects are reclaimable */
 #define SLAB_TEMPORARY		SLAB_RECLAIM_ACCOUNT	/* Objects are short-lived */

init/main.c

@@ -56,6 +56,7 @@
 #include <linux/debug_locks.h>
 #include <linux/debugobjects.h>
 #include <linux/lockdep.h>
+#include <linux/kmemleak.h>
 #include <linux/pid_namespace.h>
 #include <linux/device.h>
 #include <linux/kthread.h>
@@ -621,6 +622,7 @@ asmlinkage void __init start_kernel(void)
 	/* init some links before init_ISA_irqs() */
 	early_irq_init();
 	init_IRQ();
+	prio_tree_init();
 	init_timers();
 	hrtimers_init();
 	softirq_init();
@@ -667,6 +669,7 @@ asmlinkage void __init start_kernel(void)
 	enable_debug_pagealloc();
 	cpu_hotplug_init();
 	kmemtrace_init();
+	kmemleak_init();
 	debug_objects_mem_init();
 	idr_init_cache();
 	setup_per_cpu_pageset();
@@ -676,7 +679,6 @@ asmlinkage void __init start_kernel(void)
 	calibrate_delay();
 	pidmap_init();
 	pgtable_cache_init();
-	prio_tree_init();
 	anon_vma_init();
 #ifdef CONFIG_X86
 	if (efi_enabled)

kernel/module.c

@@ -53,6 +53,7 @@
 #include <linux/ftrace.h>
 #include <linux/async.h>
 #include <linux/percpu.h>
+#include <linux/kmemleak.h>
 
 #if 0
 #define DEBUGP printk
@@ -433,6 +434,7 @@ static void *percpu_modalloc(unsigned long size, unsigned long align,
 	unsigned long extra;
 	unsigned int i;
 	void *ptr;
+	int cpu;
 
 	if (align > PAGE_SIZE) {
 		printk(KERN_WARNING "%s: per-cpu alignment %li > %li\n",
@@ -462,6 +464,11 @@ static void *percpu_modalloc(unsigned long size, unsigned long align,
 			if (!split_block(i, size))
 				return NULL;
 
+		/* add the per-cpu scanning areas */
+		for_each_possible_cpu(cpu)
+			kmemleak_alloc(ptr + per_cpu_offset(cpu), size, 0,
+				       GFP_KERNEL);
+
 		/* Mark allocated */
 		pcpu_size[i] = -pcpu_size[i];
 		return ptr;
@@ -476,6 +483,7 @@ static void percpu_modfree(void *freeme)
 {
 	unsigned int i;
 	void *ptr = __per_cpu_start + block_size(pcpu_size[0]);
+	int cpu;
 
 	/* First entry is core kernel percpu data. */
 	for (i = 1; i < pcpu_num_used; ptr += block_size(pcpu_size[i]), i++) {
@@ -487,6 +495,10 @@ static void percpu_modfree(void *freeme)
 	BUG();
 
  free:
+	/* remove the per-cpu scanning areas */
+	for_each_possible_cpu(cpu)
+		kmemleak_free(freeme + per_cpu_offset(cpu));
+
 	/* Merge with previous? */
 	if (pcpu_size[i-1] >= 0) {
 		pcpu_size[i-1] += pcpu_size[i];
@@ -1879,6 +1891,36 @@ static void *module_alloc_update_bounds(unsigned long size)
 	return ret;
 }
 
+#ifdef CONFIG_DEBUG_KMEMLEAK
+static void kmemleak_load_module(struct module *mod, Elf_Ehdr *hdr,
+				 Elf_Shdr *sechdrs, char *secstrings)
+{
+	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);
+
+	for (i = 1; i < hdr->e_shnum; i++) {
+		if (!(sechdrs[i].sh_flags & SHF_ALLOC))
+			continue;
+		if (strncmp(secstrings + sechdrs[i].sh_name, ".data", 5) != 0
+		    && 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,
+				   sechdrs[i].sh_size, GFP_KERNEL);
+	}
+}
+#else
+static inline void kmemleak_load_module(struct module *mod, Elf_Ehdr *hdr,
+					Elf_Shdr *sechdrs, char *secstrings)
+{
+}
+#endif
+
 /* Allocate and load the module: note that size of section 0 is always
    zero, and we rely on this for optional sections. */
 static noinline struct module *load_module(void __user *umod,
@@ -2049,6 +2091,12 @@ static noinline struct module *load_module(void __user *umod,
 
 	/* Do the allocs. */
 	ptr = module_alloc_update_bounds(mod->core_size);
+	/*
+	 * The pointer to this block is stored in the module structure
+	 * which is inside the block. Just mark it as not being a
+	 * leak.
+	 */
+	kmemleak_not_leak(ptr);
 	if (!ptr) {
 		err = -ENOMEM;
 		goto free_percpu;
@@ -2057,6 +2105,13 @@ static noinline struct module *load_module(void __user *umod,
 	mod->module_core = ptr;
 
 	ptr = module_alloc_update_bounds(mod->init_size);
+	/*
+	 * The pointer to this block is stored in the module structure
+	 * which is inside the block. This block doesn't need to be
+	 * scanned as it contains data and code that will be freed
+	 * after the module is initialized.
+	 */
+	kmemleak_ignore(ptr);
 	if (!ptr && mod->init_size) {
 		err = -ENOMEM;
 		goto free_core;
@@ -2087,6 +2142,7 @@ static noinline struct module *load_module(void __user *umod,
 	}
 	/* Module has been moved. */
 	mod = (void *)sechdrs[modindex].sh_addr;
+	kmemleak_load_module(mod, hdr, sechdrs, secstrings);
 
 #if defined(CONFIG_MODULE_UNLOAD) && defined(CONFIG_SMP)
 	mod->refptr = percpu_modalloc(sizeof(local_t), __alignof__(local_t),

lib/Kconfig.debug

@@ -336,6 +336,38 @@ config SLUB_STATS
 	  out which slabs are relevant to a particular load.
 	  Try running: slabinfo -DA
 
+config DEBUG_KMEMLEAK
+	bool "Kernel memory leak detector"
+	depends on DEBUG_KERNEL && EXPERIMENTAL && (X86 || ARM) && \
+		!MEMORY_HOTPLUG
+	select DEBUG_SLAB if SLAB
+	select SLUB_DEBUG if SLUB
+	select DEBUG_FS if SYSFS
+	select STACKTRACE if STACKTRACE_SUPPORT
+	select KALLSYMS
+	help
+	  Say Y here if you want to enable the memory leak
+	  detector. The memory allocation/freeing is traced in a way
+	  similar to the Boehm's conservative garbage collector, the
+	  difference being that the orphan objects are not freed but
+	  only shown in /sys/kernel/debug/kmemleak. Enabling this
+	  feature will introduce an overhead to memory
+	  allocations. See Documentation/kmemleak.txt for more
+	  details.
+
+	  In order to access the kmemleak file, debugfs needs to be
+	  mounted (usually at /sys/kernel/debug).
+
+config DEBUG_KMEMLEAK_TEST
+	tristate "Simple test for the kernel memory leak detector"
+	depends on DEBUG_KMEMLEAK
+	help
+	  Say Y or M here to build a test for the kernel memory leak
+	  detector. This option enables a module that explicitly leaks
+	  memory.
+
+	  If unsure, say N.
+
 config DEBUG_PREEMPT
 	bool "Debug preemptible kernel"
 	depends on DEBUG_KERNEL && PREEMPT && (TRACE_IRQFLAGS_SUPPORT || PPC64)

mm/Makefile

@@ -38,3 +38,5 @@ obj-$(CONFIG_SMP) += allocpercpu.o
 endif
 obj-$(CONFIG_QUICKLIST) += quicklist.o
 obj-$(CONFIG_CGROUP_MEM_RES_CTLR) += memcontrol.o page_cgroup.o
+obj-$(CONFIG_DEBUG_KMEMLEAK) += kmemleak.o
+obj-$(CONFIG_DEBUG_KMEMLEAK_TEST) += kmemleak-test.o

mm/kmemleak-test.c

+/*
+ * mm/kmemleak-test.c
+ *
+ * Copyright (C) 2008 ARM Limited
+ * Written by Catalin Marinas <catalin.marinas@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/list.h>
+#include <linux/percpu.h>
+#include <linux/fdtable.h>
+
+#include <linux/kmemleak.h>
+
+struct test_node {
+	long header[25];
+	struct list_head list;
+	long footer[25];
+};
+
+static LIST_HEAD(test_list);
+static DEFINE_PER_CPU(void *, test_pointer);
+
+/*
+ * Some very simple testing. This function needs to be extended for
+ * proper testing.
+ */
+static int __init kmemleak_test_init(void)
+{
+	struct test_node *elem;
+	int i;
+
+	printk(KERN_INFO "Kmemleak testing\n");
+
+	/* make some orphan objects */
+	pr_info("kmemleak: kmalloc(32) = %p\n", kmalloc(32, GFP_KERNEL));
+	pr_info("kmemleak: kmalloc(32) = %p\n", kmalloc(32, GFP_KERNEL));
+	pr_info("kmemleak: kmalloc(1024) = %p\n", kmalloc(1024, GFP_KERNEL));
+	pr_info("kmemleak: kmalloc(1024) = %p\n", kmalloc(1024, GFP_KERNEL));
+	pr_info("kmemleak: kmalloc(2048) = %p\n", kmalloc(2048, GFP_KERNEL));
+	pr_info("kmemleak: kmalloc(2048) = %p\n", kmalloc(2048, GFP_KERNEL));
+	pr_info("kmemleak: kmalloc(4096) = %p\n", kmalloc(4096, GFP_KERNEL));
+	pr_info("kmemleak: kmalloc(4096) = %p\n", kmalloc(4096, GFP_KERNEL));
+#ifndef CONFIG_MODULES
+	pr_info("kmemleak: kmem_cache_alloc(files_cachep) = %p\n",
+		kmem_cache_alloc(files_cachep, GFP_KERNEL));
+	pr_info("kmemleak: kmem_cache_alloc(files_cachep) = %p\n",
+		kmem_cache_alloc(files_cachep, GFP_KERNEL));
+#endif
+	pr_info("kmemleak: vmalloc(64) = %p\n", vmalloc(64));
+	pr_info("kmemleak: vmalloc(64) = %p\n", vmalloc(64));
+	pr_info("kmemleak: vmalloc(64) = %p\n", vmalloc(64));
+	pr_info("kmemleak: vmalloc(64) = %p\n", vmalloc(64));
+	pr_info("kmemleak: vmalloc(64) = %p\n", vmalloc(64));
+
+	/*
+	 * Add elements to a list. They should only appear as orphan
+	 * after the module is removed.
+	 */
+	for (i = 0; i < 10; i++) {
+		elem = kmalloc(sizeof(*elem), GFP_KERNEL);
+		pr_info("kmemleak: kmalloc(sizeof(*elem)) = %p\n", elem);
+		if (!elem)
+			return -ENOMEM;
+		memset(elem, 0, sizeof(*elem));
+		INIT_LIST_HEAD(&elem->list);
+
+		list_add_tail(&elem->list, &test_list);
+	}
+
+	for_each_possible_cpu(i) {
+		per_cpu(test_pointer, i) = kmalloc(129, GFP_KERNEL);
+		pr_info("kmemleak: kmalloc(129) = %p\n",
+			per_cpu(test_pointer, i));
+	}
+
+	return 0;
+}
+module_init(kmemleak_test_init);
+
+static void __exit kmemleak_test_exit(void)
+{
+	struct test_node *elem, *tmp;
+
+	/*
+	 * Remove the list elements without actually freeing the
+	 * memory.
+	 */
+	list_for_each_entry_safe(elem, tmp, &test_list, list)
+		list_del(&elem->list);
+}
+module_exit(kmemleak_test_exit);
+
+MODULE_LICENSE("GPL");

mm/kmemleak.c

+/*
+ * mm/kmemleak.c
+ *
+ * Copyright (C) 2008 ARM Limited
+ * Written by Catalin Marinas <catalin.marinas@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ *
+ * For more information on the algorithm and kmemleak usage, please see
+ * Documentation/kmemleak.txt.
+ *
+ * Notes on locking
+ * ----------------
+ *
+ * The following locks and mutexes are used by kmemleak:
+ *
+ * - kmemleak_lock (rwlock): protects the object_list modifications and
+ *   accesses to the object_tree_root. The object_list is the main list
+ *   holding the metadata (struct kmemleak_object) for the allocated memory
+ *   blocks. The object_tree_root is a priority search tree used to look-up
+ *   metadata based on a pointer to the corresponding memory block.  The
+ *   kmemleak_object structures are added to the object_list and
+ *   object_tree_root in the create_object() function called from the
+ *   kmemleak_alloc() callback and removed in delete_object() called from the
+ *   kmemleak_free() callback
+ * - kmemleak_object.lock (spinlock): protects a kmemleak_object. Accesses to
+ *   the metadata (e.g. count) are protected by this lock. Note that some
+ *   members of this structure may be protected by other means (atomic or
+ *   kmemleak_lock). This lock is also held when scanning the corresponding
+ *   memory block to avoid the kernel freeing it via the kmemleak_free()
+ *   callback. This is less heavyweight than holding a global lock like
+ *   kmemleak_lock during scanning
+ * - scan_mutex (mutex): ensures that only one thread may scan the memory for
+ *   unreferenced objects at a time. The gray_list contains the objects which
+ *   are already referenced or marked as false positives and need to be
+ *   scanned. This list is only modified during a scanning episode when the
+ *   scan_mutex is held. At the end of a scan, the gray_list is always empty.
+ *   Note that the kmemleak_object.use_count is incremented when an object is
+ *   added to the gray_list and therefore cannot be freed
+ * - kmemleak_mutex (mutex): prevents multiple users of the "kmemleak" debugfs
+ *   file together with modifications to the memory scanning parameters
+ *   including the scan_thread pointer
+ *
+ * The kmemleak_object structures have a use_count incremented or decremented
+ * using the get_object()/put_object() functions. When the use_count becomes
+ * 0, this count can no longer be incremented and put_object() schedules the
+ * kmemleak_object freeing via an RCU callback. All calls to the get_object()
+ * function must be protected by rcu_read_lock() to avoid accessing a freed
+ * structure.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/sched.h>
+#include <linux/jiffies.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/kthread.h>
+#include <linux/prio_tree.h>
+#include <linux/gfp.h>
+#include <linux/fs.h>
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+#include <linux/cpumask.h>
+#include <linux/spinlock.h>
+#include <linux/mutex.h>
+#include <linux/rcupdate.h>
+#include <linux/stacktrace.h>
+#include <linux/cache.h>
+#include <linux/percpu.h>
+#include <linux/hardirq.h>
+#include <linux/mmzone.h>
+#include <linux/slab.h>
+#include <linux/thread_info.h>
+#include <linux/err.h>
+#include <linux/uaccess.h>
+#include <linux/string.h>
+#include <linux/nodemask.h>
+#include <linux/mm.h>
+
+#include <asm/sections.h>
+#include <asm/processor.h>
+#include <asm/atomic.h>
+
+#include <linux/kmemleak.h>
+
+/*
+ * Kmemleak configuration and common defines.
+ */
+#define MAX_TRACE		16	/* stack trace length */
+#define REPORTS_NR		50	/* maximum number of reported leaks */
+#define MSECS_MIN_AGE		5000	/* minimum object age for reporting */
+#define MSECS_SCAN_YIELD	10	/* CPU yielding period */
+#define SECS_FIRST_SCAN		60	/* delay before the first scan */
+#define SECS_SCAN_WAIT		600	/* subsequent auto scanning delay */
+
+#define BYTES_PER_POINTER	sizeof(void *)
+
+/* scanning area inside a memory block */
+struct kmemleak_scan_area {
+	struct hlist_node node;
+	unsigned long offset;
+	size_t length;
+};
+
+/*
+ * Structure holding the metadata for each allocated memory block.
+ * Modifications to such objects should be made while holding the
+ * object->lock. Insertions or deletions from object_list, gray_list or
+ * tree_node are already protected by the corresponding locks or mutex (see
+ * the notes on locking above). These objects are reference-counted
+ * (use_count) and freed using the RCU mechanism.
+ */
+struct kmemleak_object {
+	spinlock_t lock;
+	unsigned long flags;		/* object status flags */
+	struct list_head object_list;
+	struct list_head gray_list;
+	struct prio_tree_node tree_node;
+	struct rcu_head rcu;		/* object_list lockless traversal */
+	/* object usage count; object freed when use_count == 0 */
+	atomic_t use_count;
+	unsigned long pointer;
+	size_t size;
+	/* minimum number of a pointers found before it is considered leak */
+	int min_count;
+	/* the total number of pointers found pointing to this object */
+	int count;
+	/* memory ranges to be scanned inside an object (empty for all) */
+	struct hlist_head area_list;
+	unsigned long trace[MAX_TRACE];
+	unsigned int trace_len;
+	unsigned long jiffies;		/* creation timestamp */
+	pid_t pid;			/* pid of the current task */
+	char comm[TASK_COMM_LEN];	/* executable name */
+};
+
+/* flag representing the memory block allocation status */
+#define OBJECT_ALLOCATED	(1 << 0)
+/* flag set after the first reporting of an unreference object */
+#define OBJECT_REPORTED		(1 << 1)
+/* flag set to not scan the object */
+#define OBJECT_NO_SCAN		(1 << 2)
+
+/* the list of all allocated objects */
+static LIST_HEAD(object_list);
+/* the list of gray-colored objects (see color_gray comment below) */
+static LIST_HEAD(gray_list);
+/* prio search tree for object boundaries */
+static struct prio_tree_root object_tree_root;
+/* rw_lock protecting the access to object_list and prio_tree_root */
+static DEFINE_RWLOCK(kmemleak_lock);
+
+/* allocation caches for kmemleak internal data */
+static struct kmem_cache *object_cache;
+static struct kmem_cache *scan_area_cache;
+
+/* set if tracing memory operations is enabled */
+static atomic_t kmemleak_enabled = ATOMIC_INIT(0);
+/* set in the late_initcall if there were no errors */
+static atomic_t kmemleak_initialized = ATOMIC_INIT(0);
+/* enables or disables early logging of the memory operations */
+static atomic_t kmemleak_early_log = ATOMIC_INIT(1);
+/* set if a fata kmemleak error has occurred */
+static atomic_t kmemleak_error = ATOMIC_INIT(0);
+
+/* minimum and maximum address that may be valid pointers */
+static unsigned long min_addr = ULONG_MAX;
+static unsigned long max_addr;
+
+/* used for yielding the CPU to other tasks during scanning */
+static unsigned long next_scan_yield;
+static struct task_struct *scan_thread;
+static unsigned long jiffies_scan_yield;
+static unsigned long jiffies_min_age;
+/* delay between automatic memory scannings */
+static signed long jiffies_scan_wait;
+/* enables or disables the task stacks scanning */
+static int kmemleak_stack_scan;
+/* mutex protecting the memory scanning */
+static DEFINE_MUTEX(scan_mutex);
+/* mutex protecting the access to the /sys/kernel/debug/kmemleak file */
+static DEFINE_MUTEX(kmemleak_mutex);
+
+/* number of leaks reported (for limitation purposes) */
+static int reported_leaks;
+
+/*
+ * Early object allocation/freeing logging. Kkmemleak is initialized after the
+ * kernel allocator. However, both the kernel allocator and kmemleak may
+ * allocate memory blocks which need to be tracked. Kkmemleak defines an
+ * arbitrary buffer to hold the allocation/freeing information before it is
+ * fully initialized.
+ */
+
+/* kmemleak operation type for early logging */
+enum {
+	KMEMLEAK_ALLOC,
+	KMEMLEAK_FREE,
+	KMEMLEAK_NOT_LEAK,
+	KMEMLEAK_IGNORE,
+	KMEMLEAK_SCAN_AREA,
+	KMEMLEAK_NO_SCAN
+};
+
+/*
+ * Structure holding the information passed to kmemleak callbacks during the
+ * early logging.
+ */
+struct early_log {
+	int op_type;			/* kmemleak operation type */
+	const void *ptr;		/* allocated/freed memory block */
+	size_t size;			/* memory block size */
+	int min_count;			/* minimum reference count */
+	unsigned long offset;		/* scan area offset */
+	size_t length;			/* scan area length */
+};
+
+/* early logging buffer and current position */
+static struct early_log early_log[200];
+static int crt_early_log;
+
+static void kmemleak_disable(void);
+
+/*
+ * Print a warning and dump the stack trace.
+ */
+#define kmemleak_warn(x...)	do {	\
+	pr_warning(x);			\
+	dump_stack();			\
+} while (0)
+
+/*
+ * Macro invoked when a serious kmemleak condition occured and cannot be
+ * recovered from. Kkmemleak will be disabled and further allocation/freeing
+ * tracing no longer available.
+ */
+#define kmemleak_panic(x...)	do {	\
+	kmemleak_warn(x);		\
+	kmemleak_disable();		\
+} while (0)
+
+/*
+ * Object colors, encoded with count and min_count:
+ * - white - orphan object, not enough references to it (count < min_count)
+ * - gray  - not orphan, not marked as false positive (min_count == 0) or
+ *		sufficient references to it (count >= min_count)
+ * - black - ignore, it doesn't contain references (e.g. text section)
+ *		(min_count == -1). No function defined for this color.
+ * Newly created objects don't have any color assigned (object->count == -1)
+ * before the next memory scan when they become white.
+ */
+static int color_white(const struct kmemleak_object *object)
+{
+	return object->count != -1 && object->count < object->min_count;
+}
+
+static int color_gray(const struct kmemleak_object *object)
+{
+	return object->min_count != -1 && object->count >= object->min_count;
+}
+
+/*
+ * Objects are considered referenced if their color is gray and they have not
+ * been deleted.
+ */
+static int referenced_object(struct kmemleak_object *object)
+{
+	return (object->flags & OBJECT_ALLOCATED) && color_gray(object);
+}
+
+/*
+ * Objects are considered unreferenced only if their color is white, they have
+ * not be deleted and have a minimum age to avoid false positives caused by
+ * pointers temporarily stored in CPU registers.
+ */
+static int unreferenced_object(struct kmemleak_object *object)
+{
+	return (object->flags & OBJECT_ALLOCATED) && color_white(object) &&
+		time_is_before_eq_jiffies(object->jiffies + jiffies_min_age);
+}
+
+/*
+ * Printing of the (un)referenced objects information, either to the seq file
+ * or to the kernel log. The print_referenced/print_unreferenced functions
+ * must be called with the object->lock held.
+ */
+#define print_helper(seq, x...)	do {	\
+	struct seq_file *s = (seq);	\
+	if (s)				\
+		seq_printf(s, x);	\
+	else				\
+		pr_info(x);		\
+} while (0)
+
+static void print_referenced(struct kmemleak_object *object)
+{
+	pr_info("kmemleak: referenced object 0x%08lx (size %zu)\n",
+		object->pointer, object->size);
+}
+
+static void print_unreferenced(struct seq_file *seq,
+			       struct kmemleak_object *object)
+{
+	int i;
+
+	print_helper(seq, "kmemleak: unreferenced object 0x%08lx (size %zu):\n",
+		     object->pointer, object->size);
+	print_helper(seq, "  comm \"%s\", pid %d, jiffies %lu\n",
+		     object->comm, object->pid, object->jiffies);
+	print_helper(seq, "  backtrace:\n");
+
+	for (i = 0; i < object->trace_len; i++) {
+		void *ptr = (void *)object->trace[i];
+		print_helper(seq, "    [<%p>] %pS\n", ptr, ptr);
+	}
+}
+
+/*
+ * Print the kmemleak_object information. This function is used mainly for
+ * debugging special cases when kmemleak operations. It must be called with
+ * the object->lock held.
+ */
+static void dump_object_info(struct kmemleak_object *object)
+{
+	struct stack_trace trace;
+
+	trace.nr_entries = object->trace_len;
+	trace.entries = object->trace;
+
+	pr_notice("kmemleak: Object 0x%08lx (size %zu):\n",
+		  object->tree_node.start, object->size);
+	pr_notice("  comm \"%s\", pid %d, jiffies %lu\n",
+		  object->comm, object->pid, object->jiffies);
+	pr_notice("  min_count = %d\n", object->min_count);
+	pr_notice("  count = %d\n", object->count);
+	pr_notice("  backtrace:\n");
+	print_stack_trace(&trace, 4);
+}
+
+/*
+ * Look-up a memory block metadata (kmemleak_object) in the priority search
+ * tree based on a pointer value. If alias is 0, only values pointing to the
+ * beginning of the memory block are allowed. The kmemleak_lock must be held
+ * when calling this function.
+ */
+static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
+{
+	struct prio_tree_node *node;
+	struct prio_tree_iter iter;
+	struct kmemleak_object *object;
+
+	prio_tree_iter_init(&iter, &object_tree_root, ptr, ptr);
+	node = prio_tree_next(&iter);
+	if (node) {
+		object = prio_tree_entry(node, struct kmemleak_object,
+					 tree_node);
+		if (!alias && object->pointer != ptr) {
+			kmemleak_warn("kmemleak: Found object by alias");
+			object = NULL;
+		}
+	} else
+		object = NULL;
+
+	return object;
+}
+
+/*
+ * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
+ * that once an object's use_count reached 0, the RCU freeing was already
+ * registered and the object should no longer be used. This function must be
+ * called under the protection of rcu_read_lock().
+ */
+static int get_object(struct kmemleak_object *object)
+{
+	return atomic_inc_not_zero(&object->use_count);
+}
+
+/*
+ * RCU callback to free a kmemleak_object.
+ */
+static void free_object_rcu(struct rcu_head *rcu)
+{
+	struct hlist_node *elem, *tmp;
+	struct kmemleak_scan_area *area;
+	struct kmemleak_object *object =
+		container_of(rcu, struct kmemleak_object, rcu);
+
+	/*
+	 * Once use_count is 0 (guaranteed by put_object), there is no other
+	 * code accessing this object, hence no need for locking.
+	 */
+	hlist_for_each_entry_safe(area, elem, tmp, &object->area_list, node) {
+		hlist_del(elem);
+		kmem_cache_free(scan_area_cache, area);
+	}
+	kmem_cache_free(object_cache, object);
+}
+
+/*
+ * Decrement the object use_count. Once the count is 0, free the object using
+ * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
+ * delete_object() path, the delayed RCU freeing ensures that there is no
+ * recursive call to the kernel allocator. Lock-less RCU object_list traversal
+ * is also possible.
+ */
+static void put_object(struct kmemleak_object *object)
+{
+	if (!atomic_dec_and_test(&object->use_count))
+		return;
+
+	/* should only get here after delete_object was called */
+	WARN_ON(object->flags & OBJECT_ALLOCATED);
+
+	call_rcu(&object->rcu, free_object_rcu);
+}
+
+/*
+ * Look up an object in the prio search tree and increase its use_count.
+ */
+static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
+{
+	unsigned long flags;
+	struct kmemleak_object *object = NULL;
+
+	rcu_read_lock();
+	read_lock_irqsave(&kmemleak_lock, flags);
+	if (ptr >= min_addr && ptr < max_addr)
+		object = lookup_object(ptr, alias);
+	read_unlock_irqrestore(&kmemleak_lock, flags);
+
+	/* check whether the object is still available */
+	if (object && !get_object(object))
+		object = NULL;
+	rcu_read_unlock();
+
+	return object;
+}
+
+/*
+ * Create the metadata (struct kmemleak_object) corresponding to an allocated
+ * memory block and add it to the object_list and object_tree_root.
+ */
+static void create_object(unsigned long ptr, size_t size, int min_count,
+			  gfp_t gfp)
+{
+	unsigned long flags;
+	struct kmemleak_object *object;
+	struct prio_tree_node *node;
+	struct stack_trace trace;
+
+	object = kmem_cache_alloc(object_cache, gfp & ~GFP_SLAB_BUG_MASK);
+	if (!object) {
+		kmemleak_panic("kmemleak: Cannot allocate a kmemleak_object "
+			       "structure\n");
+		return;
+	}
+
+	INIT_LIST_HEAD(&object->object_list);
+	INIT_LIST_HEAD(&object->gray_list);
+	INIT_HLIST_HEAD(&object->area_list);
+	spin_lock_init(&object->lock);
+	atomic_set(&object->use_count, 1);
+	object->flags = OBJECT_ALLOCATED;
+	object->pointer = ptr;
+	object->size = size;
+	object->min_count = min_count;
+	object->count = -1;			/* no color initially */
+	object->jiffies = jiffies;
+
+	/* task information */
+	if (in_irq()) {
+		object->pid = 0;
+		strncpy(object->comm, "hardirq", sizeof(object->comm));
+	} else if (in_softirq()) {
+		object->pid = 0;
+		strncpy(object->comm, "softirq", sizeof(object->comm));
+	} else {
+		object->pid = current->pid;
+		/*
+		 * There is a small chance of a race with set_task_comm(),
+		 * however using get_task_comm() here may cause locking
+		 * dependency issues with current->alloc_lock. In the worst
+		 * case, the command line is not correct.
+		 */
+		strncpy(object->comm, current->comm, sizeof(object->comm));
+	}
+
+	/* kernel backtrace */
+	trace.max_entries = MAX_TRACE;
+	trace.nr_entries = 0;
+	trace.entries = object->trace;
+	trace.skip = 1;
+	save_stack_trace(&trace);
+	object->trace_len = trace.nr_entries;
+
+	INIT_PRIO_TREE_NODE(&object->tree_node);
+	object->tree_node.start = ptr;
+	object->tree_node.last = ptr + size - 1;
+
+	write_lock_irqsave(&kmemleak_lock, flags);
+	min_addr = min(min_addr, ptr);
+	max_addr = max(max_addr, ptr + size);
+	node = prio_tree_insert(&object_tree_root, &object->tree_node);
+	/*
+	 * The code calling the kernel does not yet have the pointer to the
+	 * memory block to be able to free it.  However, we still hold the
+	 * kmemleak_lock here in case parts of the kernel started freeing
+	 * random memory blocks.
+	 */
+	if (node != &object->tree_node) {
+		unsigned long flags;
+
+		kmemleak_panic("kmemleak: Cannot insert 0x%lx into the object "
+			       "search tree (already existing)\n", ptr);
+		object = lookup_object(ptr, 1);
+		spin_lock_irqsave(&object->lock, flags);
+		dump_object_info(object);
+		spin_unlock_irqrestore(&object->lock, flags);
+
+		goto out;
+	}
+	list_add_tail_rcu(&object->object_list, &object_list);
+out:
+	write_unlock_irqrestore(&kmemleak_lock, flags);
+}
+
+/*
+ * Remove the metadata (struct kmemleak_object) for a memory block from the
+ * object_list and object_tree_root and decrement its use_count.
+ */
+static void delete_object(unsigned long ptr)
+{
+	unsigned long flags;
+	struct kmemleak_object *object;
+
+	write_lock_irqsave(&kmemleak_lock, flags);
+	object = lookup_object(ptr, 0);
+	if (!object) {
+		kmemleak_warn("kmemleak: Freeing unknown object at 0x%08lx\n",
+			      ptr);
+		write_unlock_irqrestore(&kmemleak_lock, flags);
+		return;
+	}
+	prio_tree_remove(&object_tree_root, &object->tree_node);
+	list_del_rcu(&object->object_list);
+	write_unlock_irqrestore(&kmemleak_lock, flags);
+
+	WARN_ON(!(object->flags & OBJECT_ALLOCATED));
+	WARN_ON(atomic_read(&object->use_count) < 1);
+
+	/*
+	 * Locking here also ensures that the corresponding memory block
+	 * cannot be freed when it is being scanned.
+	 */
+	spin_lock_irqsave(&object->lock, flags);
+	if (object->flags & OBJECT_REPORTED)
+		print_referenced(object);
+	object->flags &= ~OBJECT_ALLOCATED;
+	spin_unlock_irqrestore(&object->lock, flags);
+	put_object(object);
+}
+
+/*
+ * Make a object permanently as gray-colored so that it can no longer be
+ * reported as a leak. This is used in general to mark a false positive.
+ */
+static void make_gray_object(unsigned long ptr)
+{
+	unsigned long flags;
+	struct kmemleak_object *object;
+
+	object = find_and_get_object(ptr, 0);
+	if (!object) {
+		kmemleak_warn("kmemleak: Graying unknown object at 0x%08lx\n",
+			      ptr);
+		return;
+	}
+
+	spin_lock_irqsave(&object->lock, flags);
+	object->min_count = 0;
+	spin_unlock_irqrestore(&object->lock, flags);
+	put_object(object);
+}
+
+/*
+ * Mark the object as black-colored so that it is ignored from scans and
+ * reporting.
+ */
+static void make_black_object(unsigned long ptr)
+{
+	unsigned long flags;
+	struct kmemleak_object *object;
+
+	object = find_and_get_object(ptr, 0);
+	if (!object) {
+		kmemleak_warn("kmemleak: Blacking unknown object at 0x%08lx\n",
+			      ptr);
+		return;
+	}
+
+	spin_lock_irqsave(&object->lock, flags);
+	object->min_count = -1;
+	spin_unlock_irqrestore(&object->lock, flags);
+	put_object(object);
+}
+
+/*
+ * Add a scanning area to the object. If at least one such area is added,
+ * kmemleak will only scan these ranges rather than the whole memory block.
+ */
+static void add_scan_area(unsigned long ptr, unsigned long offset,
+			  size_t length, gfp_t gfp)
+{
+	unsigned long flags;
+	struct kmemleak_object *object;
+	struct kmemleak_scan_area *area;
+
+	object = find_and_get_object(ptr, 0);
+	if (!object) {
+		kmemleak_warn("kmemleak: Adding scan area to unknown "
+			      "object at 0x%08lx\n", ptr);
+		return;
+	}
+
+	area = kmem_cache_alloc(scan_area_cache, gfp & ~GFP_SLAB_BUG_MASK);
+	if (!area) {
+		kmemleak_warn("kmemleak: Cannot allocate a scan area\n");
+		goto out;
+	}
+
+	spin_lock_irqsave(&object->lock, flags);
+	if (offset + length > object->size) {
+		kmemleak_warn("kmemleak: Scan area larger than object "
+			      "0x%08lx\n", ptr);
+		dump_object_info(object);
+		kmem_cache_free(scan_area_cache, area);
+		goto out_unlock;
+	}
+
+	INIT_HLIST_NODE(&area->node);
+	area->offset = offset;
+	area->length = length;
+
+	hlist_add_head(&area->node, &object->area_list);
+out_unlock:
+	spin_unlock_irqrestore(&object->lock, flags);
+out:
+	put_object(object);
+}
+
+/*
+ * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
+ * pointer. Such object will not be scanned by kmemleak but references to it
+ * are searched.
+ */
+static void object_no_scan(unsigned long ptr)
+{
+	unsigned long flags;
+	struct kmemleak_object *object;
+
+	object = find_and_get_object(ptr, 0);
+	if (!object) {
+		kmemleak_warn("kmemleak: Not scanning unknown object at "
+			      "0x%08lx\n", ptr);
+		return;
+	}
+
+	spin_lock_irqsave(&object->lock, flags);
+	object->flags |= OBJECT_NO_SCAN;
+	spin_unlock_irqrestore(&object->lock, flags);
+	put_object(object);
+}
+
+/*
+ * Log an early kmemleak_* call to the early_log buffer. These calls will be
+ * processed later once kmemleak is fully initialized.
+ */
+static void log_early(int op_type, const void *ptr, size_t size,
+		      int min_count, unsigned long offset, size_t length)
+{
+	unsigned long flags;
+	struct early_log *log;
+
+	if (crt_early_log >= ARRAY_SIZE(early_log)) {
+		kmemleak_panic("kmemleak: Early log buffer exceeded\n");
+		return;
+	}
+
+	/*
+	 * There is no need for locking since the kernel is still in UP mode
+	 * at this stage. Disabling the IRQs is enough.
+	 */
+	local_irq_save(flags);
+	log = &early_log[crt_early_log];
+	log->op_type = op_type;
+	log->ptr = ptr;
+	log->size = size;
+	log->min_count = min_count;
+	log->offset = offset;
+	log->length = length;
+	crt_early_log++;
+	local_irq_restore(flags);
+}
+
+/*
+ * Memory allocation function callback. This function is called from the
+ * kernel allocators when a new block is allocated (kmem_cache_alloc, kmalloc,
+ * vmalloc etc.).
+ */
+void kmemleak_alloc(const void *ptr, size_t size, int min_count, gfp_t gfp)
+{
+	pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count);
+
+	if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
+		create_object((unsigned long)ptr, size, min_count, gfp);
+	else if (atomic_read(&kmemleak_early_log))
+		log_early(KMEMLEAK_ALLOC, ptr, size, min_count, 0, 0);
+}
+EXPORT_SYMBOL_GPL(kmemleak_alloc);
+
+/*
+ * Memory freeing function callback. This function is called from the kernel
+ * allocators when a block is freed (kmem_cache_free, kfree, vfree etc.).
+ */
+void kmemleak_free(const void *ptr)
+{
+	pr_debug("%s(0x%p)\n", __func__, ptr);
+
+	if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
+		delete_object((unsigned long)ptr);
+	else if (atomic_read(&kmemleak_early_log))
+		log_early(KMEMLEAK_FREE, ptr, 0, 0, 0, 0);
+}
+EXPORT_SYMBOL_GPL(kmemleak_free);
+
+/*
+ * Mark an already allocated memory block as a false positive. This will cause
+ * the block to no longer be reported as leak and always be scanned.
+ */
+void kmemleak_not_leak(const void *ptr)
+{
+	pr_debug("%s(0x%p)\n", __func__, ptr);
+
+	if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
+		make_gray_object((unsigned long)ptr);
+	else if (atomic_read(&kmemleak_early_log))
+		log_early(KMEMLEAK_NOT_LEAK, ptr, 0, 0, 0, 0);
+}
+EXPORT_SYMBOL(kmemleak_not_leak);
+
+/*
+ * Ignore a memory block. This is usually done when it is known that the
+ * corresponding block is not a leak and does not contain any references to
+ * other allocated memory blocks.
+ */
+void kmemleak_ignore(const void *ptr)
+{
+	pr_debug("%s(0x%p)\n", __func__, ptr);
+
+	if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
+		make_black_object((unsigned long)ptr);
+	else if (atomic_read(&kmemleak_early_log))
+		log_early(KMEMLEAK_IGNORE, ptr, 0, 0, 0, 0);
+}
+EXPORT_SYMBOL(kmemleak_ignore);
+
+/*
+ * Limit the range to be scanned in an allocated memory block.
+ */
+void kmemleak_scan_area(const void *ptr, unsigned long offset, size_t length,
+			gfp_t gfp)
+{
+	pr_debug("%s(0x%p)\n", __func__, ptr);
+
+	if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
+		add_scan_area((unsigned long)ptr, offset, length, gfp);
+	else if (atomic_read(&kmemleak_early_log))
+		log_early(KMEMLEAK_SCAN_AREA, ptr, 0, 0, offset, length);
+}
+EXPORT_SYMBOL(kmemleak_scan_area);
+
+/*
+ * Inform kmemleak not to scan the given memory block.
+ */
+void kmemleak_no_scan(const void *ptr)
+{
+	pr_debug("%s(0x%p)\n", __func__, ptr);
+
+	if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
+		object_no_scan((unsigned long)ptr);
+	else if (atomic_read(&kmemleak_early_log))
+		log_early(KMEMLEAK_NO_SCAN, ptr, 0, 0, 0, 0);
+}
+EXPORT_SYMBOL(kmemleak_no_scan);
+
+/*
+ * Yield the CPU so that other tasks get a chance to run.  The yielding is
+ * rate-limited to avoid excessive number of calls to the schedule() function
+ * during memory scanning.
+ */
+static void scan_yield(void)
+{
+	might_sleep();
+
+	if (time_is_before_eq_jiffies(next_scan_yield)) {
+		schedule();
+		next_scan_yield = jiffies + jiffies_scan_yield;
+	}
+}
+
+/*
+ * Memory scanning is a long process and it needs to be interruptable. This
+ * function checks whether such interrupt condition occured.
+ */
+static int scan_should_stop(void)
+{
+	if (!atomic_read(&kmemleak_enabled))
+		return 1;
+
+	/*
+	 * This function may be called from either process or kthread context,
+	 * hence the need to check for both stop conditions.
+	 */
+	if (current->mm)
+		return signal_pending(current);
+	else
+		return kthread_should_stop();
+
+	return 0;
+}
+
+/*
+ * Scan a memory block (exclusive range) for valid pointers and add those
+ * found to the gray list.
+ */
+static void scan_block(void *_start, void *_end,
+		       struct kmemleak_object *scanned)
+{
+	unsigned long *ptr;
+	unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER);
+	unsigned long *end = _end - (BYTES_PER_POINTER - 1);
+
+	for (ptr = start; ptr < end; ptr++) {
+		unsigned long flags;
+		unsigned long pointer = *ptr;
+		struct kmemleak_object *object;
+
+		if (scan_should_stop())
+			break;
+
+		/*
+		 * When scanning a memory block with a corresponding
+		 * kmemleak_object, the CPU yielding is handled in the calling
+		 * code since it holds the object->lock to avoid the block
+		 * freeing.
+		 */
+		if (!scanned)
+			scan_yield();
+
+		object = find_and_get_object(pointer, 1);
+		if (!object)
+			continue;
+		if (object == scanned) {
+			/* self referenced, ignore */
+			put_object(object);
+			continue;
+		}
+
+		/*
+		 * Avoid the lockdep recursive warning on object->lock being
+		 * previously acquired in scan_object(). These locks are
+		 * enclosed by scan_mutex.
+		 */
+		spin_lock_irqsave_nested(&object->lock, flags,
+					 SINGLE_DEPTH_NESTING);
+		if (!color_white(object)) {
+			/* non-orphan, ignored or new */
+			spin_unlock_irqrestore(&object->lock, flags);
+			put_object(object);
+			continue;
+		}
+
+		/*
+		 * Increase the object's reference count (number of pointers
+		 * to the memory block). If this count reaches the required
+		 * minimum, the object's color will become gray and it will be
+		 * added to the gray_list.
+		 */
+		object->count++;
+		if (color_gray(object))
+			list_add_tail(&object->gray_list, &gray_list);
+		else
+			put_object(object);
+		spin_unlock_irqrestore(&object->lock, flags);
+	}
+}
+
+/*
+ * Scan a memory block corresponding to a kmemleak_object. A condition is
+ * that object->use_count >= 1.
+ */
+static void scan_object(struct kmemleak_object *object)
+{
+	struct kmemleak_scan_area *area;
+	struct hlist_node *elem;
+	unsigned long flags;
+
+	/*
+	 * Once the object->lock is aquired, the corresponding memory block
+	 * cannot be freed (the same lock is aquired in delete_object).
+	 */
+	spin_lock_irqsave(&object->lock, flags);
+	if (object->flags & OBJECT_NO_SCAN)
+		goto out;
+	if (!(object->flags & OBJECT_ALLOCATED))
+		/* already freed object */
+		goto out;
+	if (hlist_empty(&object->area_list))
+		scan_block((void *)object->pointer,
+			   (void *)(object->pointer + object->size), object);
+	else
+		hlist_for_each_entry(area, elem, &object->area_list, node)
+			scan_block((void *)(object->pointer + area->offset),
+				   (void *)(object->pointer + area->offset
+					    + area->length), object);
+out:
+	spin_unlock_irqrestore(&object->lock, flags);
+}
+
+/*
+ * Scan data sections and all the referenced memory blocks allocated via the
+ * kernel's standard allocators. This function must be called with the
+ * scan_mutex held.
+ */
+static void kmemleak_scan(void)
+{
+	unsigned long flags;
+	struct kmemleak_object *object, *tmp;
+	struct task_struct *task;
+	int i;
+
+	/* prepare the kmemleak_object's */
+	rcu_read_lock();
+	list_for_each_entry_rcu(object, &object_list, object_list) {
+		spin_lock_irqsave(&object->lock, flags);
+#ifdef DEBUG
+		/*
+		 * With a few exceptions there should be a maximum of
+		 * 1 reference to any object at this point.
+		 */
+		if (atomic_read(&object->use_count) > 1) {
+			pr_debug("kmemleak: object->use_count = %d\n",
+				 atomic_read(&object->use_count));
+			dump_object_info(object);
+		}
+#endif
+		/* reset the reference count (whiten the object) */
+		object->count = 0;
+		if (color_gray(object) && get_object(object))
+			list_add_tail(&object->gray_list, &gray_list);
+
+		spin_unlock_irqrestore(&object->lock, flags);
+	}
+	rcu_read_unlock();
+
+	/* data/bss scanning */
+	scan_block(_sdata, _edata, NULL);
+	scan_block(__bss_start, __bss_stop, NULL);
+
+#ifdef CONFIG_SMP
+	/* per-cpu sections scanning */
+	for_each_possible_cpu(i)
+		scan_block(__per_cpu_start + per_cpu_offset(i),
+			   __per_cpu_end + per_cpu_offset(i), NULL);
+#endif
+
+	/*
+	 * Struct page scanning for each node. The code below is not yet safe
+	 * with MEMORY_HOTPLUG.
+	 */
+	for_each_online_node(i) {
+		pg_data_t *pgdat = NODE_DATA(i);
+		unsigned long start_pfn = pgdat->node_start_pfn;
+		unsigned long end_pfn = start_pfn + pgdat->node_spanned_pages;
+		unsigned long pfn;
+
+		for (pfn = start_pfn; pfn < end_pfn; pfn++) {
+			struct page *page;
+
+			if (!pfn_valid(pfn))
+				continue;
+			page = pfn_to_page(pfn);
+			/* only scan if page is in use */
+			if (page_count(page) == 0)
+				continue;
+			scan_block(page, page + 1, NULL);
+		}
+	}
+
+	/*
+	 * Scanning the task stacks may introduce false negatives and it is
+	 * not enabled by default.
+	 */
+	if (kmemleak_stack_scan) {
+		read_lock(&tasklist_lock);
+		for_each_process(task)
+			scan_block(task_stack_page(task),
+				   task_stack_page(task) + THREAD_SIZE, NULL);
+		read_unlock(&tasklist_lock);
+	}
+
+	/*
+	 * Scan the objects already referenced from the sections scanned
+	 * above. More objects will be referenced and, if there are no memory
+	 * leaks, all the objects will be scanned. The list traversal is safe
+	 * for both tail additions and removals from inside the loop. The
+	 * kmemleak objects cannot be freed from outside the loop because their
+	 * use_count was increased.
+	 */
+	object = list_entry(gray_list.next, typeof(*object), gray_list);
+	while (&object->gray_list != &gray_list) {
+		scan_yield();
+
+		/* may add new objects to the list */
+		if (!scan_should_stop())
+			scan_object(object);
+
+		tmp = list_entry(object->gray_list.next, typeof(*object),
+				 gray_list);
+
+		/* remove the object from the list and release it */
+		list_del(&object->gray_list);
+		put_object(object);
+
+		object = tmp;
+	}
+	WARN_ON(!list_empty(&gray_list));
+}
+
+/*
+ * Thread function performing automatic memory scanning. Unreferenced objects
+ * at the end of a memory scan are reported but only the first time.
+ */
+static int kmemleak_scan_thread(void *arg)
+{
+	static int first_run = 1;
+
+	pr_info("kmemleak: Automatic memory scanning thread started\n");
+
+	/*
+	 * Wait before the first scan to allow the system to fully initialize.
+	 */
+	if (first_run) {
+		first_run = 0;
+		ssleep(SECS_FIRST_SCAN);
+	}
+
+	while (!kthread_should_stop()) {
+		struct kmemleak_object *object;
+		signed long timeout = jiffies_scan_wait;
+
+		mutex_lock(&scan_mutex);
+
+		kmemleak_scan();
+		reported_leaks = 0;
+
+		rcu_read_lock();
+		list_for_each_entry_rcu(object, &object_list, object_list) {
+			unsigned long flags;
+
+			if (reported_leaks >= REPORTS_NR)
+				break;
+			spin_lock_irqsave(&object->lock, flags);
+			if (!(object->flags & OBJECT_REPORTED) &&
+			    unreferenced_object(object)) {
+				print_unreferenced(NULL, object);
+				object->flags |= OBJECT_REPORTED;
+				reported_leaks++;
+			} else if ((object->flags & OBJECT_REPORTED) &&
+				   referenced_object(object)) {
+				print_referenced(object);
+				object->flags &= ~OBJECT_REPORTED;
+			}
+			spin_unlock_irqrestore(&object->lock, flags);
+		}
+		rcu_read_unlock();
+
+		mutex_unlock(&scan_mutex);
+		/* wait before the next scan */
+		while (timeout && !kthread_should_stop())
+			timeout = schedule_timeout_interruptible(timeout);
+	}
+
+	pr_info("kmemleak: Automatic memory scanning thread ended\n");
+
+	return 0;
+}
+
+/*
+ * Start the automatic memory scanning thread. This function must be called
+ * with the kmemleak_mutex held.
+ */
+void start_scan_thread(void)
+{
+	if (scan_thread)
+		return;
+	scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak");
+	if (IS_ERR(scan_thread)) {
+		pr_warning("kmemleak: Failed to create the scan thread\n");
+		scan_thread = NULL;
+	}
+}
+
+/*
+ * Stop the automatic memory scanning thread. This function must be called
+ * with the kmemleak_mutex held.
+ */
+void stop_scan_thread(void)
+{
+	if (scan_thread) {
+		kthread_stop(scan_thread);
+		scan_thread = NULL;
+	}
+}
+
+/*
+ * Iterate over the object_list and return the first valid object at or after
+ * the required position with its use_count incremented. The function triggers
+ * a memory scanning when the pos argument points to the first position.
+ */
+static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
+{
+	struct kmemleak_object *object;
+	loff_t n = *pos;
+
+	if (!n) {
+		kmemleak_scan();
+		reported_leaks = 0;
+	}
+	if (reported_leaks >= REPORTS_NR)
+		return NULL;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(object, &object_list, object_list) {
+		if (n-- > 0)
+			continue;
+		if (get_object(object))
+			goto out;
+	}
+	object = NULL;
+out:
+	rcu_read_unlock();
+	return object;
+}
+
+/*
+ * Return the next object in the object_list. The function decrements the
+ * use_count of the previous object and increases that of the next one.
+ */
+static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	struct kmemleak_object *prev_obj = v;
+	struct kmemleak_object *next_obj = NULL;
+	struct list_head *n = &prev_obj->object_list;
+
+	++(*pos);
+	if (reported_leaks >= REPORTS_NR)
+		goto out;
+
+	rcu_read_lock();
+	list_for_each_continue_rcu(n, &object_list) {
+		next_obj = list_entry(n, struct kmemleak_object, object_list);
+		if (get_object(next_obj))
+			break;
+	}
+	rcu_read_unlock();
+out:
+	put_object(prev_obj);
+	return next_obj;
+}
+
+/*
+ * Decrement the use_count of the last object required, if any.
+ */
+static void kmemleak_seq_stop(struct seq_file *seq, void *v)
+{
+	if (v)
+		put_object(v);
+}
+
+/*
+ * Print the information for an unreferenced object to the seq file.
+ */
+static int kmemleak_seq_show(struct seq_file *seq, void *v)
+{
+	struct kmemleak_object *object = v;
+	unsigned long flags;
+
+	spin_lock_irqsave(&object->lock, flags);
+	if (!unreferenced_object(object))
+		goto out;
+	print_unreferenced(seq, object);
+	reported_leaks++;
+out:
+	spin_unlock_irqrestore(&object->lock, flags);
+	return 0;
+}
+
+static const struct seq_operations kmemleak_seq_ops = {
+	.start = kmemleak_seq_start,
+	.next  = kmemleak_seq_next,
+	.stop  = kmemleak_seq_stop,
+	.show  = kmemleak_seq_show,
+};
+
+static int kmemleak_open(struct inode *inode, struct file *file)
+{
+	int ret = 0;
+
+	if (!atomic_read(&kmemleak_enabled))
+		return -EBUSY;
+
+	ret = mutex_lock_interruptible(&kmemleak_mutex);
+	if (ret < 0)
+		goto out;
+	if (file->f_mode & FMODE_READ) {
+		ret = mutex_lock_interruptible(&scan_mutex);
+		if (ret < 0)
+			goto kmemleak_unlock;
+		ret = seq_open(file, &kmemleak_seq_ops);
+		if (ret < 0)
+			goto scan_unlock;
+	}
+	return ret;
+
+scan_unlock:
+	mutex_unlock(&scan_mutex);
+kmemleak_unlock:
+	mutex_unlock(&kmemleak_mutex);
+out:
+	return ret;
+}
+
+static int kmemleak_release(struct inode *inode, struct file *file)
+{
+	int ret = 0;
+
+	if (file->f_mode & FMODE_READ) {
+		seq_release(inode, file);
+		mutex_unlock(&scan_mutex);
+	}
+	mutex_unlock(&kmemleak_mutex);
+
+	return ret;
+}
+
+/*
+ * File write operation to configure kmemleak at run-time. The following
+ * commands can be written to the /sys/kernel/debug/kmemleak file:
+ *   off	- disable kmemleak (irreversible)
+ *   stack=on	- enable the task stacks scanning
+ *   stack=off	- disable the tasks stacks scanning
+ *   scan=on	- start the automatic memory scanning thread
+ *   scan=off	- stop the automatic memory scanning thread
+ *   scan=...	- set the automatic memory scanning period in seconds (0 to
+ *		  disable it)
+ */
+static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
+			      size_t size, loff_t *ppos)
+{
+	char buf[64];
+	int buf_size;
+
+	if (!atomic_read(&kmemleak_enabled))
+		return -EBUSY;
+
+	buf_size = min(size, (sizeof(buf) - 1));
+	if (strncpy_from_user(buf, user_buf, buf_size) < 0)
+		return -EFAULT;
+	buf[buf_size] = 0;
+
+	if (strncmp(buf, "off", 3) == 0)
+		kmemleak_disable();
+	else if (strncmp(buf, "stack=on", 8) == 0)
+		kmemleak_stack_scan = 1;
+	else if (strncmp(buf, "stack=off", 9) == 0)
+		kmemleak_stack_scan = 0;
+	else if (strncmp(buf, "scan=on", 7) == 0)
+		start_scan_thread();
+	else if (strncmp(buf, "scan=off", 8) == 0)
+		stop_scan_thread();
+	else if (strncmp(buf, "scan=", 5) == 0) {
+		unsigned long secs;
+		int err;
+
+		err = strict_strtoul(buf + 5, 0, &secs);
+		if (err < 0)
+			return err;
+		stop_scan_thread();
+		if (secs) {
+			jiffies_scan_wait = msecs_to_jiffies(secs * 1000);
+			start_scan_thread();
+		}
+	} else
+		return -EINVAL;
+
+	/* ignore the rest of the buffer, only one command at a time */
+	*ppos += size;
+	return size;
+}
+
+static const struct file_operations kmemleak_fops = {
+	.owner		= THIS_MODULE,
+	.open		= kmemleak_open,
+	.read		= seq_read,
+	.write		= kmemleak_write,
+	.llseek		= seq_lseek,
+	.release	= kmemleak_release,
+};
+
+/*
+ * Perform the freeing of the kmemleak internal objects after waiting for any
+ * current memory scan to complete.
+ */
+static int kmemleak_cleanup_thread(void *arg)
+{
+	struct kmemleak_object *object;
+
+	mutex_lock(&kmemleak_mutex);
+	stop_scan_thread();
+	mutex_unlock(&kmemleak_mutex);
+
+	mutex_lock(&scan_mutex);
+	rcu_read_lock();
+	list_for_each_entry_rcu(object, &object_list, object_list)
+		delete_object(object->pointer);
+	rcu_read_unlock();
+	mutex_unlock(&scan_mutex);
+
+	return 0;
+}
+
+/*
+ * Start the clean-up thread.
+ */
+static void kmemleak_cleanup(void)
+{
+	struct task_struct *cleanup_thread;
+
+	cleanup_thread = kthread_run(kmemleak_cleanup_thread, NULL,
+				     "kmemleak-clean");
+	if (IS_ERR(cleanup_thread))
+		pr_warning("kmemleak: Failed to create the clean-up thread\n");
+}
+
+/*
+ * Disable kmemleak. No memory allocation/freeing will be traced once this
+ * function is called. Disabling kmemleak is an irreversible operation.
+ */
+static void kmemleak_disable(void)
+{
+	/* atomically check whether it was already invoked */
+	if (atomic_cmpxchg(&kmemleak_error, 0, 1))
+		return;
+
+	/* stop any memory operation tracing */
+	atomic_set(&kmemleak_early_log, 0);
+	atomic_set(&kmemleak_enabled, 0);
+
+	/* check whether it is too early for a kernel thread */
+	if (atomic_read(&kmemleak_initialized))
+		kmemleak_cleanup();
+
+	pr_info("Kernel memory leak detector disabled\n");
+}
+
+/*
+ * Allow boot-time kmemleak disabling (enabled by default).
+ */
+static int kmemleak_boot_config(char *str)
+{
+	if (!str)
+		return -EINVAL;
+	if (strcmp(str, "off") == 0)
+		kmemleak_disable();
+	else if (strcmp(str, "on") != 0)
+		return -EINVAL;
+	return 0;
+}
+early_param("kmemleak", kmemleak_boot_config);
+
+/*
+ * Kkmemleak initialization.
+ */
+void __init kmemleak_init(void)
+{
+	int i;
+	unsigned long flags;
+
+	jiffies_scan_yield = msecs_to_jiffies(MSECS_SCAN_YIELD);
+	jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
+	jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000);
+
+	object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE);
+	scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
+	INIT_PRIO_TREE_ROOT(&object_tree_root);
+
+	/* the kernel is still in UP mode, so disabling the IRQs is enough */
+	local_irq_save(flags);
+	if (!atomic_read(&kmemleak_error)) {
+		atomic_set(&kmemleak_enabled, 1);
+		atomic_set(&kmemleak_early_log, 0);
+	}
+	local_irq_restore(flags);
+
+	/*
+	 * This is the point where tracking allocations is safe. Automatic
+	 * scanning is started during the late initcall. Add the early logged
+	 * callbacks to the kmemleak infrastructure.
+	 */
+	for (i = 0; i < crt_early_log; i++) {
+		struct early_log *log = &early_log[i];
+
+		switch (log->op_type) {
+		case KMEMLEAK_ALLOC:
+			kmemleak_alloc(log->ptr, log->size, log->min_count,
+				       GFP_KERNEL);
+			break;
+		case KMEMLEAK_FREE:
+			kmemleak_free(log->ptr);
+			break;
+		case KMEMLEAK_NOT_LEAK:
+			kmemleak_not_leak(log->ptr);
+			break;
+		case KMEMLEAK_IGNORE:
+			kmemleak_ignore(log->ptr);
+			break;
+		case KMEMLEAK_SCAN_AREA:
+			kmemleak_scan_area(log->ptr, log->offset, log->length,
+					   GFP_KERNEL);
+			break;
+		case KMEMLEAK_NO_SCAN:
+			kmemleak_no_scan(log->ptr);
+			break;
+		default:
+			WARN_ON(1);
+		}
+	}
+}
+
+/*
+ * Late initialization function.
+ */
+static int __init kmemleak_late_init(void)
+{
+	struct dentry *dentry;
+
+	atomic_set(&kmemleak_initialized, 1);
+
+	if (atomic_read(&kmemleak_error)) {
+		/*
+		 * Some error occured and kmemleak was disabled. There is a
+		 * small chance that kmemleak_disable() was called immediately
+		 * after setting kmemleak_initialized and we may end up with
+		 * two clean-up threads but serialized by scan_mutex.
+		 */
+		kmemleak_cleanup();
+		return -ENOMEM;
+	}
+
+	dentry = debugfs_create_file("kmemleak", S_IRUGO, NULL, NULL,
+				     &kmemleak_fops);
+	if (!dentry)
+		pr_warning("kmemleak: Failed to create the debugfs kmemleak "
+			   "file\n");
+	mutex_lock(&kmemleak_mutex);
+	start_scan_thread();
+	mutex_unlock(&kmemleak_mutex);
+
+	pr_info("Kernel memory leak detector initialized\n");
+
+	return 0;
+}
+late_initcall(kmemleak_late_init);

mm/page_alloc.c

@@ -46,6 +46,7 @@
 #include <linux/page-isolation.h>
 #include <linux/page_cgroup.h>
 #include <linux/debugobjects.h>
+#include <linux/kmemleak.h>
 
 #include <asm/tlbflush.h>
 #include <asm/div64.h>
@@ -4546,6 +4547,16 @@ void *__init alloc_large_system_hash(const char *tablename,
 	if (_hash_mask)
 		*_hash_mask = (1 << log2qty) - 1;
 
+	/*
+	 * If hashdist is set, the table allocation is done with __vmalloc()
+	 * which invokes the kmemleak_alloc() callback. This function may also
+	 * be called before the slab and kmemleak are initialised when
+	 * kmemleak simply buffers the request to be executed later
+	 * (GFP_ATOMIC flag ignored in this case).
+	 */
+	if (!hashdist)
+		kmemleak_alloc(table, size, 1, GFP_ATOMIC);
+
 	return table;
 }
 

mm/slab.c

@@ -107,6 +107,7 @@
 #include	<linux/string.h>
 #include	<linux/uaccess.h>
 #include	<linux/nodemask.h>
+#include	<linux/kmemleak.h>
 #include	<linux/mempolicy.h>
 #include	<linux/mutex.h>
 #include	<linux/fault-inject.h>
@@ -178,13 +179,13 @@
 			 SLAB_STORE_USER | \
 			 SLAB_RECLAIM_ACCOUNT | SLAB_PANIC | \
 			 SLAB_DESTROY_BY_RCU | SLAB_MEM_SPREAD | \
-			 SLAB_DEBUG_OBJECTS)
+			 SLAB_DEBUG_OBJECTS | SLAB_NOLEAKTRACE)
 #else
 # define CREATE_MASK	(SLAB_HWCACHE_ALIGN | \
 			 SLAB_CACHE_DMA | \
 			 SLAB_RECLAIM_ACCOUNT | SLAB_PANIC | \
 			 SLAB_DESTROY_BY_RCU | SLAB_MEM_SPREAD | \
-			 SLAB_DEBUG_OBJECTS)
+			 SLAB_DEBUG_OBJECTS | SLAB_NOLEAKTRACE)
 #endif
 
 /*
@@ -964,6 +965,14 @@ static struct array_cache *alloc_arraycache(int node, int entries,
 	struct array_cache *nc = NULL;
 
 	nc = kmalloc_node(memsize, gfp, node);
+	/*
+	 * The array_cache structures contain pointers to free object.
+	 * However, when such objects are allocated or transfered to another
+	 * cache the pointers are not cleared and they could be counted as
+	 * valid references during a kmemleak scan. Therefore, kmemleak must
+	 * not scan such objects.
+	 */
+	kmemleak_no_scan(nc);
 	if (nc) {
 		nc->avail = 0;
 		nc->limit = entries;
@@ -2625,6 +2634,14 @@ static struct slab *alloc_slabmgmt(struct kmem_cache *cachep, void *objp,
 		/* Slab management obj is off-slab. */
 		slabp = kmem_cache_alloc_node(cachep->slabp_cache,
 					      local_flags, nodeid);
+		/*
+		 * If the first object in the slab is leaked (it's allocated
+		 * but no one has a reference to it), we want to make sure
+		 * 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);
 		if (!slabp)
 			return NULL;
 	} else {
@@ -3145,6 +3162,12 @@ static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags)
 		STATS_INC_ALLOCMISS(cachep);
 		objp = cache_alloc_refill(cachep, flags);
 	}
+	/*
+	 * To avoid a false negative, if an object that is in one of the
+	 * per-CPU caches is leaked, we need to make sure kmemleak doesn't
+	 * treat the array pointers as a reference to the object.
+	 */
+	kmemleak_erase(&ac->entry[ac->avail]);
 	return objp;
 }
 
@@ -3364,6 +3387,8 @@ __cache_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid,
   out:
 	local_irq_restore(save_flags);
 	ptr = cache_alloc_debugcheck_after(cachep, flags, ptr, caller);
+	kmemleak_alloc_recursive(ptr, obj_size(cachep), 1, cachep->flags,
+				 flags);
 
 	if (unlikely((flags & __GFP_ZERO) && ptr))
 		memset(ptr, 0, obj_size(cachep));
@@ -3419,6 +3444,8 @@ __cache_alloc(struct kmem_cache *cachep, gfp_t flags, void *caller)
 	objp = __do_cache_alloc(cachep, flags);
 	local_irq_restore(save_flags);
 	objp = cache_alloc_debugcheck_after(cachep, flags, objp, caller);
+	kmemleak_alloc_recursive(objp, obj_size(cachep), 1, cachep->flags,
+				 flags);
 	prefetchw(objp);
 
 	if (unlikely((flags & __GFP_ZERO) && objp))
@@ -3534,6 +3561,7 @@ static inline void __cache_free(struct kmem_cache *cachep, void *objp)
 	struct array_cache *ac = cpu_cache_get(cachep);
 
 	check_irq_off();
+	kmemleak_free_recursive(objp, cachep->flags);
 	objp = cache_free_debugcheck(cachep, objp, __builtin_return_address(0));
 
 	/*

mm/slob.c

@@ -67,6 +67,7 @@
 #include <linux/rcupdate.h>
 #include <linux/list.h>
 #include <linux/kmemtrace.h>
+#include <linux/kmemleak.h>
 #include <asm/atomic.h>
 
 /*
@@ -509,6 +510,7 @@ void *__kmalloc_node(size_t size, gfp_t gfp, int node)
 				   size, PAGE_SIZE << order, gfp, node);
 	}
 
+	kmemleak_alloc(ret, size, 1, gfp);
 	return ret;
 }
 EXPORT_SYMBOL(__kmalloc_node);
@@ -521,6 +523,7 @@ void kfree(const void *block)
 
 	if (unlikely(ZERO_OR_NULL_PTR(block)))
 		return;
+	kmemleak_free(block);
 
 	sp = slob_page(block);
 	if (is_slob_page(sp)) {
@@ -584,12 +587,14 @@ struct kmem_cache *kmem_cache_create(const char *name, size_t size,
 	} else if (flags & SLAB_PANIC)
 		panic("Cannot create slab cache %s\n", name);
 
+	kmemleak_alloc(c, sizeof(struct kmem_cache), 1, GFP_KERNEL);
 	return c;
 }
 EXPORT_SYMBOL(kmem_cache_create);
 
 void kmem_cache_destroy(struct kmem_cache *c)
 {
+	kmemleak_free(c);
 	slob_free(c, sizeof(struct kmem_cache));
 }
 EXPORT_SYMBOL(kmem_cache_destroy);
@@ -613,6 +618,7 @@ void *kmem_cache_alloc_node(struct kmem_cache *c, gfp_t flags, int node)
 	if (c->ctor)
 		c->ctor(b);
 
+	kmemleak_alloc_recursive(b, c->size, 1, c->flags, flags);
 	return b;
 }
 EXPORT_SYMBOL(kmem_cache_alloc_node);
@@ -635,6 +641,7 @@ static void kmem_rcu_free(struct rcu_head *head)
 
 void kmem_cache_free(struct kmem_cache *c, void *b)
 {
+	kmemleak_free_recursive(b, c->flags);
 	if (unlikely(c->flags & SLAB_DESTROY_BY_RCU)) {
 		struct slob_rcu *slob_rcu;
 		slob_rcu = b + (c->size - sizeof(struct slob_rcu));

mm/slub.c

@@ -20,6 +20,7 @@
 #include <linux/kmemtrace.h>
 #include <linux/cpu.h>
 #include <linux/cpuset.h>
+#include <linux/kmemleak.h>
 #include <linux/mempolicy.h>
 #include <linux/ctype.h>
 #include <linux/debugobjects.h>
@@ -143,7 +144,7 @@
  * Set of flags that will prevent slab merging
  */
 #define SLUB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
-		SLAB_TRACE | SLAB_DESTROY_BY_RCU)
+		SLAB_TRACE | SLAB_DESTROY_BY_RCU | SLAB_NOLEAKTRACE)
 
 #define SLUB_MERGE_SAME (SLAB_DEBUG_FREE | SLAB_RECLAIM_ACCOUNT | \
 		SLAB_CACHE_DMA)
@@ -1617,6 +1618,7 @@ static __always_inline void *slab_alloc(struct kmem_cache *s,
 	if (unlikely((gfpflags & __GFP_ZERO) && object))
 		memset(object, 0, objsize);
 
+	kmemleak_alloc_recursive(object, objsize, 1, s->flags, gfpflags);
 	return object;
 }
 
@@ -1746,6 +1748,7 @@ static __always_inline void slab_free(struct kmem_cache *s,
 	struct kmem_cache_cpu *c;
 	unsigned long flags;
 
+	kmemleak_free_recursive(x, s->flags);
 	local_irq_save(flags);
 	c = get_cpu_slab(s, smp_processor_id());
 	debug_check_no_locks_freed(object, c->objsize);

mm/vmalloc.c

@@ -24,6 +24,7 @@
 #include <linux/radix-tree.h>
 #include <linux/rcupdate.h>
 #include <linux/pfn.h>
+#include <linux/kmemleak.h>
 
 #include <asm/atomic.h>
 #include <asm/uaccess.h>
@@ -1326,6 +1327,9 @@ static void __vunmap(const void *addr, int deallocate_pages)
 void vfree(const void *addr)
 {
 	BUG_ON(in_interrupt());
+
+	kmemleak_free(addr);
+
 	__vunmap(addr, 1);
 }
 EXPORT_SYMBOL(vfree);
@@ -1438,8 +1442,17 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
 
 void *__vmalloc_area(struct vm_struct *area, gfp_t gfp_mask, pgprot_t prot)
 {
-	return __vmalloc_area_node(area, gfp_mask, prot, -1,
-					__builtin_return_address(0));
+	void *addr = __vmalloc_area_node(area, gfp_mask, prot, -1,
+					 __builtin_return_address(0));
+
+	/*
+	 * A ref_count = 3 is needed because the vm_struct and vmap_area
+	 * structures allocated in the __get_vm_area_node() function contain
+	 * references to the virtual address of the vmalloc'ed block.
+	 */
+	kmemleak_alloc(addr, area->size - PAGE_SIZE, 3, gfp_mask);
+
+	return addr;
 }
 
 /**
@@ -1458,6 +1471,8 @@ static void *__vmalloc_node(unsigned long size, gfp_t gfp_mask, pgprot_t prot,
 						int node, void *caller)
 {
 	struct vm_struct *area;
+	void *addr;
+	unsigned long real_size = size;
 
 	size = PAGE_ALIGN(size);
 	if (!size || (size >> PAGE_SHIFT) > num_physpages)
@@ -1469,7 +1484,16 @@ static void *__vmalloc_node(unsigned long size, gfp_t gfp_mask, pgprot_t prot,
 	if (!area)
 		return NULL;
 
-	return __vmalloc_area_node(area, gfp_mask, prot, node, caller);
+	addr = __vmalloc_area_node(area, gfp_mask, prot, node, caller);
+
+	/*
+	 * A ref_count = 3 is needed because the vm_struct and vmap_area
+	 * structures allocated in the __get_vm_area_node() function contain
+	 * references to the virtual address of the vmalloc'ed block.
+	 */
+	kmemleak_alloc(addr, real_size, 3, gfp_mask);
+
+	return addr;
 }
 
 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)