This is a new version (0.3) of the kernel memory leak detector. See
the Documentation/kmemleak.txt file for a more detailed
description. The patches are also available from
http://homepage.ntlworld.com/cmarinas/kmemleak/ (to be uploaded
shortly).
What's new in this version:
- more clean-up
- initial kernel modules support. It scans the data sections in a
module while ignoring the text areas
- minor optimisation to avoid radix-tree lookup when updating
the pointer information
- DEBUG_FS selected automatically (until/if a different method of
triggering the memory scanning is implemented)
To do:
- better testing
- support for pointer aliases in kernel modules (i.e. container_of
usage in modules)
- test Ingo's suggestion on task stacks scanning
- NUMA support
--
Catalin
From: Catalin Marinas <[email protected]>
This patch adds the base support for the kernel memory leak detector. It
traces the memory allocation/freeing in a way similar to the Boehm's
conservative garbage collector, the difference being that the orphan
pointers are not freed but only shown in /proc/memleak. Enabling this
feature would introduce an overhead to memory allocations.
Signed-off-by: Catalin Marinas <[email protected]>
---
include/linux/kernel.h | 7
include/linux/memleak.h | 76 ++++
init/main.c | 3
lib/Kconfig.debug | 33 ++
mm/Makefile | 2
mm/memleak.c | 1013 +++++++++++++++++++++++++++++++++++++++++++++++
6 files changed, 1131 insertions(+), 3 deletions(-)
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index f4fc576..9155457 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -13,6 +13,7 @@ #include <linux/stddef.h>
#include <linux/types.h>
#include <linux/compiler.h>
#include <linux/bitops.h>
+#include <linux/memleak.h>
#include <asm/byteorder.h>
#include <asm/bug.h>
@@ -284,9 +285,13 @@ #define max_t(type,x,y) \
* @member: the name of the member within the struct.
*
*/
-#define container_of(ptr, type, member) ({ \
+#define __container_of(ptr, type, member) ({ \
const typeof( ((type *)0)->member ) *__mptr = (ptr); \
(type *)( (char *)__mptr - offsetof(type,member) );})
+#define container_of(ptr, type, member) ({ \
+ DECLARE_MEMLEAK_OFFSET(container_of, type, member); \
+ __container_of(ptr, type, member); \
+})
/*
* Check at compile time that something is of a particular type.
diff --git a/include/linux/memleak.h b/include/linux/memleak.h
new file mode 100644
index 0000000..2de897c
--- /dev/null
+++ b/include/linux/memleak.h
@@ -0,0 +1,76 @@
+/*
+ * include/linux/memleak.h
+ *
+ * Copyright (C) 2006 ARM Limited
+ * Written by Catalin Marinas <[email protected]>
+ *
+ * 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 __MEMLEAK_H
+#define __MEMLEAK_H
+
+#include <linux/stddef.h>
+
+#ifdef CONFIG_DEBUG_MEMLEAK
+
+struct memleak_offset {
+ unsigned long offset;
+ unsigned long size;
+ unsigned long member_size;
+};
+
+/* if offsetof(type, member) is not a constant known at compile time,
+ * just use 0 instead since we cannot add it to the
+ * .init.memleak_offsets section
+ */
+#define memleak_offsetof(type, member) \
+ (__builtin_constant_p(offsetof(type, member)) ? \
+ offsetof(type, member) : 0)
+
+#define DECLARE_MEMLEAK_OFFSET(name, type, member) \
+ static const struct memleak_offset \
+ __attribute__ ((__section__ (".init.memleak_offsets"))) \
+ __attribute_used__ __memleak_offset__##name = { \
+ memleak_offsetof(type, member), \
+ sizeof(type), \
+ sizeof(((type *)0)->member) \
+ }
+
+extern void memleak_debug_init(void);
+extern void memleak_debug_alloc(const void *ptr, size_t size, int ref_count);
+extern void memleak_debug_free(const void *ptr);
+extern void memleak_debug_resize(const void *ptr, size_t size);
+extern void memleak_debug_not_leak(const void *ptr);
+extern void memleak_debug_ignore(const void *ptr);
+extern void memleak_debug_scan_area(const void *ptr, unsigned long offset, size_t length);
+
+#define memleak_debug_erase(ptr) do { (ptr) = NULL; } while (0)
+
+#else
+
+#define DECLARE_MEMLEAK_OFFSET(name, type, member)
+
+#define memleak_debug_init()
+#define memleak_debug_alloc(ptr, size, ref_count)
+#define memleak_debug_free(ptr)
+#define memleak_debug_resize(ptr, size)
+#define memleak_debug_not_leak(ptr)
+#define memleak_debug_ignore(ptr)
+#define memleak_debug_scan_area(ptr, offset, length)
+#define memleak_debug_erase(ptr)
+
+#endif /* CONFIG_DEBUG_MEMLEAK */
+
+#endif /* __MEMLEAK_H */
diff --git a/init/main.c b/init/main.c
index f715b9b..acc6ad2 100644
--- a/init/main.c
+++ b/init/main.c
@@ -513,6 +513,8 @@ #endif
cpuset_init_early();
mem_init();
kmem_cache_init();
+ radix_tree_init();
+ memleak_debug_init();
setup_per_cpu_pageset();
numa_policy_init();
if (late_time_init)
@@ -533,7 +535,6 @@ #endif
key_init();
security_init();
vfs_caches_init(num_physpages);
- radix_tree_init();
signals_init();
/* rootfs populating might need page-writeback */
page_writeback_init();
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index ccb0c1f..821565a 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -89,6 +89,39 @@ config DEBUG_SLAB_LEAK
bool "Memory leak debugging"
depends on DEBUG_SLAB
+menuconfig DEBUG_MEMLEAK
+ bool "Kernel memory leak detector"
+ default n
+ depends on EXPERIMENTAL && DEBUG_KERNEL && SLAB
+ depends on !NUMA
+ select DEBUG_FS
+ 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 pointers are not freed but
+ only shown in /sys/kernel/debug/memleak. Enabling this
+ feature will introduce an overhead to memory allocations.
+
+config DEBUG_MEMLEAK_TRACE_LENGTH
+ int "KMemLeak stack trace length"
+ default 4
+ depends on DEBUG_MEMLEAK && FRAME_POINTER
+ help
+ This option sets the length of the stack trace for the
+ allocated pointers tracked by kmemleak.
+
+config DEBUG_MEMLEAK_PREINIT_POINTERS
+ int "KMemLeak pre-init actions buffer size"
+ default 2048
+ depends on DEBUG_MEMLEAK
+ help
+ This is the buffer for storing the memory allocation/freeing
+ calls before kmemleak is fully initialized. Each element in
+ the buffer takes 20 bytes on a 32 bit architecture. This
+ buffer will be freed once the system initialization is
+ completed.
+
config DEBUG_PREEMPT
bool "Debug preemptible kernel"
depends on DEBUG_KERNEL && PREEMPT
diff --git a/mm/Makefile b/mm/Makefile
index 0b8f73f..d487d96 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -23,4 +23,4 @@ obj-$(CONFIG_SLAB) += slab.o
obj-$(CONFIG_MEMORY_HOTPLUG) += memory_hotplug.o
obj-$(CONFIG_FS_XIP) += filemap_xip.o
obj-$(CONFIG_MIGRATION) += migrate.o
-
+obj-$(CONFIG_DEBUG_MEMLEAK) += memleak.o
diff --git a/mm/memleak.c b/mm/memleak.c
new file mode 100644
index 0000000..6ffdb6c
--- /dev/null
+++ b/mm/memleak.c
@@ -0,0 +1,1013 @@
+/*
+ * mm/memleak.c
+ *
+ * Copyright (C) 2006 ARM Limited
+ * Written by Catalin Marinas <[email protected]>
+ *
+ * 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
+ */
+
+/* #define DEBUG */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/radix-tree.h>
+#include <linux/gfp.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/kallsyms.h>
+#include <linux/mman.h>
+#include <linux/nodemask.h>
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+#include <linux/vmalloc.h>
+#include <linux/mutex.h>
+#include <linux/cpumask.h>
+
+#include <asm/bitops.h>
+#include <asm/sections.h>
+#include <asm/percpu.h>
+#include <asm/processor.h>
+#include <asm/thread_info.h>
+
+#include <linux/memleak.h>
+
+#ifdef CONFIG_FRAME_POINTER
+#define MAX_TRACE CONFIG_DEBUG_MEMLEAK_TRACE_LENGTH
+#else
+#define MAX_TRACE 1
+#endif
+
+#define PREINIT_POINTERS CONFIG_DEBUG_MEMLEAK_PREINIT_POINTERS
+#define BYTES_PER_WORD sizeof(void *)
+
+/* define this if you want the task stacks to be scanned (with an
+ * increased chance of false negatives) */
+/* #define TASK_STACK_SCAN */
+
+extern struct memleak_offset __memleak_offsets_start[];
+extern struct memleak_offset __memleak_offsets_end[];
+
+struct memleak_alias {
+ struct hlist_node node;
+ unsigned long offset;
+};
+
+struct memleak_scan_area {
+ struct hlist_node node;
+ unsigned long offset;
+ size_t length;
+};
+
+struct memleak_pointer {
+ struct list_head pointer_list;
+ struct list_head gray_list;
+ unsigned long pointer;
+ size_t size;
+ int ref_count; /* the minimum encounters of the value */
+ int count; /* the ecounters of the value */
+ struct hlist_head *alias_list;
+ struct hlist_head area_list; /* areas to be scanned (or empty for all) */
+ unsigned long trace[MAX_TRACE];
+};
+
+typedef enum {
+ MEMLEAK_ALLOC,
+ MEMLEAK_FREE,
+ MEMLEAK_RESIZE,
+ MEMLEAK_NOT_LEAK,
+ MEMLEAK_IGNORE,
+ MEMLEAK_SCAN_AREA
+} memleak_action_t;
+
+struct memleak_preinit_pointer {
+ memleak_action_t type;
+ const void *pointer;
+ unsigned long offset;
+ size_t size;
+ int ref_count;
+};
+
+/* Pointer colors, encoded with count and ref_count:
+ * - white - orphan block, i.e. not enough references to it (ref_count >= 1)
+ * - gray - referred at least once and therefore non-orphan (ref_count == 0)
+ * - black - ignore; it doesn't contain references (text section) (ref_count == -1)
+ */
+#define COLOR_WHITE(pointer) ((pointer)->count != -1 && (pointer)->count < (pointer)->ref_count)
+#define COLOR_GRAY(pointer) ((pointer)->ref_count != -1 && (pointer)->count >= (pointer)->ref_count)
+#define COLOR_BLACK(pointer) ((pointer)->ref_count == -1)
+
+/* Tree storing the pointer aliases indexed by size */
+static RADIX_TREE(alias_tree, GFP_KERNEL);
+/* Tree storing all the possible pointers, indexed by the pointer value */
+static RADIX_TREE(pointer_tree, GFP_ATOMIC);
+/* The list of all allocated pointers */
+static LIST_HEAD(pointer_list);
+/* The list of the gray pointers */
+static LIST_HEAD(gray_list);
+
+static kmem_cache_t *pointer_cache;
+/* Used to avoid recursive call via the kmalloc/kfree functions */
+static spinlock_t memleak_lock = SPIN_LOCK_UNLOCKED;
+static cpumask_t memleak_cpu_mask = CPU_MASK_NONE;
+static DEFINE_MUTEX(memleak_mutex);
+static int memleak_initialized = 0;
+static int __initdata preinit_pos = 0;
+static struct memleak_preinit_pointer __initdata preinit_pointers[PREINIT_POINTERS];
+/* last allocated pointer (optimization); protected by memleak_lock */
+static struct memleak_pointer *last_pointer = NULL;
+
+static void dump_pointer_info(struct memleak_pointer *pointer)
+{
+#ifdef CONFIG_KALLSYMS
+ char namebuf[KSYM_NAME_LEN + 1] = "";
+ char *modname;
+ unsigned long symsize;
+ unsigned long offset = 0;
+#endif
+#ifdef DEBUG
+ struct memleak_alias *alias;
+ struct hlist_node *elem;
+#endif
+ int i;
+
+ printk(KERN_NOTICE "kmemleak: pointer 0x%08lx:\n", pointer->pointer);
+#ifdef DEBUG
+ printk(KERN_NOTICE " size = %d\n", pointer->size);
+ printk(KERN_NOTICE " ref_count = %d\n", pointer->ref_count);
+ printk(KERN_NOTICE " count = %d\n", pointer->count);
+ printk(KERN_NOTICE " aliases:\n");
+ if (pointer->alias_list)
+ hlist_for_each_entry(alias, elem, pointer->alias_list, node)
+ printk(KERN_NOTICE " 0x%lx\n", alias->offset);
+ printk(KERN_NOTICE " trace:\n");
+#endif
+ for (i = 0; i < MAX_TRACE; i++) {
+ unsigned long trace = pointer->trace[i];
+
+ if (!trace)
+ break;
+#ifdef CONFIG_KALLSYMS
+ kallsyms_lookup(trace, &symsize, &offset, &modname, namebuf);
+ printk(KERN_NOTICE " %lx: <%s>\n", trace, namebuf);
+#else
+ printk(KERN_NOTICE " %lx\n", trace);
+#endif
+ }
+}
+
+/* Insert an element into the aliases radix tree.
+ * Return 0 on success.
+ */
+static int __init insert_alias(unsigned long size, unsigned long offset)
+{
+ int ret = 0;
+ struct hlist_head *alias_list;
+ struct memleak_alias *alias;
+
+ /* Note that offset == size is not a bug (see
+ * container_of usage in ipc/utils.c) but we ignore it
+ * because the alias can overlap with valid pointers
+ */
+ if (offset > size)
+ BUG();
+ else if (offset == 0 || offset == size) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ offset &= ~(BYTES_PER_WORD - 1);
+
+ alias_list = radix_tree_lookup(&alias_tree, size);
+ if (alias_list) {
+ struct hlist_node *elem;
+
+ hlist_for_each_entry(alias, elem, alias_list, node) {
+ if (alias->offset == offset) {
+ ret = -EEXIST;
+ goto out;
+ }
+ }
+ } else {
+ alias_list = kmalloc(sizeof(*alias_list), GFP_KERNEL);
+ if (!alias_list)
+ panic("kmemleak: cannot allocate initial memory\n");
+ INIT_HLIST_HEAD(alias_list);
+
+ ret = radix_tree_insert(&alias_tree, size, alias_list);
+ if (ret)
+ panic("kmemleak: cannot insert into the aliases radix tree: %d\n", ret);
+ }
+
+ alias = kmalloc(sizeof(*alias), GFP_KERNEL);
+ if (!alias)
+ panic("kmemleak: cannot allocate initial memory\n");
+ INIT_HLIST_NODE(&alias->node);
+ alias->offset = offset;
+
+ hlist_add_head(&alias->node, alias_list);
+
+ out:
+ return ret;
+}
+
+static inline struct memleak_pointer *get_cached_pointer(unsigned long ptr)
+{
+ if (!last_pointer || ptr != last_pointer->pointer)
+ last_pointer = radix_tree_lookup(&pointer_tree, ptr);
+ return last_pointer;
+}
+
+/* Insert a pointer and its aliases into the pointer radix tree */
+static inline void insert_pointer(unsigned long ptr, size_t size, int ref_count)
+{
+ struct memleak_alias *alias;
+ struct hlist_node *elem;
+ struct memleak_pointer *pointer;
+ int err;
+#ifdef CONFIG_FRAME_POINTER
+ int i;
+ void *frame;
+#endif
+
+ pointer = kmem_cache_alloc(pointer_cache, SLAB_ATOMIC);
+ if (!pointer)
+ panic("kmemleak: cannot allocate a memleak_pointer structure\n");
+
+ last_pointer = pointer;
+
+ INIT_LIST_HEAD(&pointer->pointer_list);
+ INIT_LIST_HEAD(&pointer->gray_list);
+ INIT_HLIST_HEAD(&pointer->area_list);
+ pointer->pointer = ptr;
+ pointer->size = size;
+ pointer->ref_count = ref_count;
+ pointer->count = -1;
+ pointer->alias_list = radix_tree_lookup(&alias_tree, size);
+
+#ifdef CONFIG_FRAME_POINTER
+ frame = __builtin_frame_address(0);
+ for (i = 0; i < MAX_TRACE; i++) {
+ void *stack = task_stack_page(current);
+
+ if (frame < stack || frame > stack + THREAD_SIZE - BYTES_PER_WORD) {
+ pointer->trace[i] = 0;
+ continue;
+ }
+
+ pointer->trace[i] = arch_call_address(frame);
+ frame = arch_prev_frame(frame);
+ /* we don't need the return to do_exit() */
+ if (kstack_end(frame))
+ pointer->trace[i] = 0;
+ }
+#else
+ pointer->trace[0] = (unsigned long)__builtin_return_address(0);
+#endif
+
+ err = radix_tree_insert(&pointer_tree, ptr, pointer);
+ if (err) {
+ dump_stack();
+ panic("kmemleak: cannot insert into the pointer radix tree: %d\n", err);
+ }
+
+ if (pointer->alias_list) {
+ hlist_for_each_entry(alias, elem, pointer->alias_list, node) {
+ if (alias->offset >= size)
+ BUG();
+
+ err = radix_tree_insert(&pointer_tree, ptr + alias->offset, pointer);
+ if (err) {
+ dump_stack();
+ panic("kmemleak: cannot insert alias into the pointer radix tree: %d\n", err);
+ }
+ }
+ }
+
+ list_add_tail_rcu(&pointer->pointer_list, &pointer_list);
+}
+
+/* Remove a pointer and its aliases from the pointer radix tree */
+static inline void delete_pointer(unsigned long ptr)
+{
+ struct memleak_alias *alias;
+ struct hlist_node *elem;
+ struct memleak_pointer *pointer;
+ struct memleak_scan_area *area;
+
+ pointer = radix_tree_delete(&pointer_tree, ptr);
+ if (!pointer) {
+ dump_stack();
+ printk(KERN_WARNING "kmemleak: freeing unknown pointer value 0x%08lx\n", ptr);
+ return;
+ }
+ if (pointer->pointer != ptr) {
+ dump_stack();
+ dump_pointer_info(pointer);
+ panic("kmemleak: freeing pointer by alias 0x%08lx\n", ptr);
+ }
+
+ if (last_pointer && ptr == last_pointer->pointer)
+ last_pointer = NULL;
+
+ if (COLOR_WHITE(pointer)) {
+ dump_stack();
+ dump_pointer_info(pointer);
+ printk(KERN_WARNING "kmemleak: freeing orphan pointer 0x%08lx\n", ptr);
+ }
+
+ if (pointer->alias_list) {
+ hlist_for_each_entry(alias, elem, pointer->alias_list, node) {
+ if (!radix_tree_delete(&pointer_tree, ptr + alias->offset)) {
+ dump_stack();
+ dump_pointer_info(pointer);
+ panic("kmemleak: cannot find pointer alias 0x%08lx, 0x%lx\n",
+ ptr, alias->offset);
+ }
+ }
+ }
+
+ hlist_for_each_entry_rcu(area, elem, &pointer->area_list, node) {
+ hlist_del_rcu(elem);
+ kfree(area);
+ }
+
+ list_del_rcu(&pointer->pointer_list);
+ kmem_cache_free(pointer_cache, pointer);
+}
+
+/* Re-create the pointer aliases according to the new size information */
+static inline void resize_pointer(unsigned long ptr, size_t size)
+{
+ struct memleak_alias *alias;
+ struct hlist_node *elem;
+ struct memleak_pointer *pointer;
+ int err;
+
+ pointer = get_cached_pointer(ptr);
+ if (!pointer) {
+ dump_stack();
+ panic("kmemleak: resizing unknown pointer value 0x%08lx\n", ptr);
+ }
+ if (pointer->pointer != ptr) {
+ dump_stack();
+ dump_pointer_info(pointer);
+ panic("kmemleak: resizing pointer by alias 0x%08lx\n", ptr);
+ }
+
+ /* remove old aliases */
+ if (pointer->alias_list) {
+ hlist_for_each_entry(alias, elem, pointer->alias_list, node) {
+ if (!radix_tree_delete(&pointer_tree, ptr + alias->offset)) {
+ dump_stack();
+ dump_pointer_info(pointer);
+ panic("kmemleak: cannot find pointer alias 0x%08lx, 0x%lx\n",
+ ptr, alias->offset);
+ }
+ }
+ }
+
+ /* add the new aliases. We don't update the pointer->size
+ * because the real block size should be scanned */
+ pointer->alias_list = radix_tree_lookup(&alias_tree, size);
+ if (pointer->alias_list) {
+ hlist_for_each_entry(alias, elem, pointer->alias_list, node) {
+ if (alias->offset >= size)
+ BUG();
+
+ err = radix_tree_insert(&pointer_tree, ptr + alias->offset, pointer);
+ if (err) {
+ dump_stack();
+ dump_pointer_info(pointer);
+ panic("kmemleak: cannot insert alias into the pointer radix tree: %d\n", err);
+ }
+ }
+ }
+}
+
+/* Make a pointer permanently gray (false positive) */
+static inline void make_gray_pointer(unsigned long ptr)
+{
+ struct memleak_pointer *pointer;
+
+ pointer = get_cached_pointer(ptr);
+ if (!pointer) {
+ dump_stack();
+ panic("kmemleak: graying unknown pointer value 0x%08lx\n", ptr);
+ }
+ if (pointer->pointer != ptr) {
+ dump_stack();
+ dump_pointer_info(pointer);
+ panic("kmemleak: graying pointer by alias 0x%08lx\n", ptr);
+ }
+
+ pointer->ref_count = 0;
+}
+
+/* Mark the pointer as black */
+static inline void make_black_pointer(unsigned long ptr)
+{
+ struct memleak_pointer *pointer;
+
+ pointer = get_cached_pointer(ptr);
+ if (!pointer) {
+ dump_stack();
+ panic("kmemleak: blacking unknown pointer value 0x%08lx\n", ptr);
+ }
+ if (pointer->pointer != ptr) {
+ dump_stack();
+ dump_pointer_info(pointer);
+ panic("kmemleak: blacking pointer by alias 0x%08lx\n", ptr);
+ }
+
+ pointer->ref_count = -1;
+}
+
+/* Add a scanning area to the pointer */
+static inline void add_scan_area(unsigned long ptr, unsigned long offset, size_t length)
+{
+ struct memleak_pointer *pointer;
+ struct memleak_scan_area *area;
+
+ pointer = get_cached_pointer(ptr);
+ if (!pointer) {
+ dump_stack();
+ panic("kmemleak: adding scan area to unknown pointer value 0x%08lx\n", ptr);
+ }
+ if (pointer->pointer != ptr) {
+ dump_stack();
+ dump_pointer_info(pointer);
+ panic("kmemleak: adding scan area to pointer by alias 0x%08lx\n", ptr);
+ }
+ if (offset + length > pointer->size) {
+ dump_stack();
+ dump_pointer_info(pointer);
+ panic("kmemleak: scan area larger than block 0x%08lx\n", ptr);
+ }
+
+ area = kmalloc(sizeof(*area), GFP_ATOMIC);
+ if (!area)
+ panic("kmemleak: cannot allocate a scan area\n");
+
+ INIT_HLIST_NODE(&area->node);
+ area->offset = offset;
+ area->length = length;
+
+ hlist_add_head(&area->node, &pointer->area_list);
+}
+
+/* Allocation function hook */
+void memleak_debug_alloc(const void *ptr, size_t size, int ref_count)
+{
+ unsigned long flags;
+ unsigned int cpu_id = smp_processor_id();
+
+ if (!ptr)
+ return;
+
+ local_irq_save(flags);
+
+ if (!memleak_initialized) {
+ /* no need for SMP locking since this block is
+ * executed before the other CPUs are started */
+ struct memleak_preinit_pointer *pointer;
+
+ BUG_ON(cpu_id != 0);
+
+ if (preinit_pos >= PREINIT_POINTERS)
+ panic("kmemleak: preinit pointers buffer overflow\n");
+ pointer = &preinit_pointers[preinit_pos++];
+
+ pointer->type = MEMLEAK_ALLOC;
+ pointer->pointer = ptr;
+ pointer->size = size;
+ pointer->ref_count = ref_count;
+
+ goto out;
+ }
+
+ /* avoid recursive calls. After disabling the interrupts, the
+ * only calls to this function on the same CPU should be from
+ * kmemleak itself and we ignore them. Calls from other CPU's
+ * would wait on the spin_lock.
+ */
+ if (!cpu_test_and_set(cpu_id, memleak_cpu_mask)) {
+ pr_debug("%s(0x%p, %d, %d)\n", __FUNCTION__, ptr, size, ref_count);
+
+ spin_lock(&memleak_lock);
+ insert_pointer((unsigned long)ptr, size, ref_count);
+ spin_unlock(&memleak_lock);
+
+ cpu_clear(cpu_id, memleak_cpu_mask);
+ }
+
+ out:
+ local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(memleak_debug_alloc);
+
+/* Freeing function hook */
+void memleak_debug_free(const void *ptr)
+{
+ unsigned long flags;
+ unsigned int cpu_id = smp_processor_id();
+
+ if (!ptr)
+ return;
+
+ local_irq_save(flags);
+
+ if (!memleak_initialized) {
+ struct memleak_preinit_pointer *pointer;
+
+ BUG_ON(cpu_id != 0);
+
+ if (preinit_pos >= PREINIT_POINTERS)
+ panic("kmemleak: preinit pointers buffer overflow\n");
+ pointer = &preinit_pointers[preinit_pos++];
+
+ pointer->type = MEMLEAK_FREE;
+ pointer->pointer = ptr;
+
+ goto out;
+ }
+
+ /* avoid recursive calls. See memleak_debug_alloc() for an explanation */
+ if (!cpu_test_and_set(cpu_id, memleak_cpu_mask)) {
+ pr_debug("%s(0x%p)\n", __FUNCTION__, ptr);
+
+ spin_lock(&memleak_lock);
+ delete_pointer((unsigned long)ptr);
+ spin_unlock(&memleak_lock);
+
+ cpu_clear(cpu_id, memleak_cpu_mask);
+ }
+
+ out:
+ local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(memleak_debug_free);
+
+/* Change the size information of an allocated memory block */
+void memleak_debug_resize(const void *ptr, size_t size)
+{
+ unsigned long flags;
+ unsigned int cpu_id = smp_processor_id();
+
+ if (!ptr)
+ return;
+
+ local_irq_save(flags);
+
+ if (!memleak_initialized) {
+ struct memleak_preinit_pointer *pointer;
+
+ BUG_ON(cpu_id != 0);
+
+ if (preinit_pos >= PREINIT_POINTERS)
+ panic("kmemleak: preinit pointers buffer overflow\n");
+ pointer = &preinit_pointers[preinit_pos++];
+
+ pointer->type = MEMLEAK_RESIZE;
+ pointer->pointer = ptr;
+ pointer->size = size;
+
+ goto out;
+ }
+
+ /* avoid recursive calls. See memleak_debug_alloc() for an explanation */
+ if (!cpu_test_and_set(cpu_id, memleak_cpu_mask)) {
+ pr_debug("%s(0x%p, %d)\n", __FUNCTION__, ptr, size);
+
+ spin_lock(&memleak_lock);
+ resize_pointer((unsigned long)ptr, size);
+ spin_unlock(&memleak_lock);
+
+ cpu_clear(cpu_id, memleak_cpu_mask);
+ }
+
+ out:
+ local_irq_restore(flags);
+}
+EXPORT_SYMBOL(memleak_debug_resize);
+
+/* Mark a pointer as a false positive */
+void memleak_debug_not_leak(const void *ptr)
+{
+ unsigned long flags;
+ unsigned int cpu_id = smp_processor_id();
+
+ if (!ptr)
+ return;
+
+ local_irq_save(flags);
+
+ if (!memleak_initialized) {
+ struct memleak_preinit_pointer *pointer;
+
+ BUG_ON(cpu_id != 0);
+
+ if (preinit_pos >= PREINIT_POINTERS)
+ panic("kmemleak: preinit pointers buffer overflow\n");
+ pointer = &preinit_pointers[preinit_pos++];
+
+ pointer->type = MEMLEAK_NOT_LEAK;
+ pointer->pointer = ptr;
+
+ goto out;
+ }
+
+ /* avoid recursive calls. See memleak_debug_alloc() for an explanation */
+ if (!cpu_test_and_set(cpu_id, memleak_cpu_mask)) {
+ pr_debug("%s(0x%p)\n", __FUNCTION__, ptr);
+
+ spin_lock(&memleak_lock);
+ make_gray_pointer((unsigned long)ptr);
+ spin_unlock(&memleak_lock);
+
+ cpu_clear(cpu_id, memleak_cpu_mask);
+ }
+
+ out:
+ local_irq_restore(flags);
+}
+EXPORT_SYMBOL(memleak_debug_not_leak);
+
+/* Ignore this memory block */
+void memleak_debug_ignore(const void *ptr)
+{
+ unsigned long flags;
+ unsigned int cpu_id = smp_processor_id();
+
+ if (!ptr)
+ return;
+
+ local_irq_save(flags);
+
+ if (!memleak_initialized) {
+ struct memleak_preinit_pointer *pointer;
+
+ BUG_ON(cpu_id != 0);
+
+ if (preinit_pos >= PREINIT_POINTERS)
+ panic("kmemleak: preinit pointers buffer overflow\n");
+ pointer = &preinit_pointers[preinit_pos++];
+
+ pointer->type = MEMLEAK_IGNORE;
+ pointer->pointer = ptr;
+
+ goto out;
+ }
+
+ /* avoid recursive calls. See memleak_debug_alloc() for an explanation */
+ if (!cpu_test_and_set(cpu_id, memleak_cpu_mask)) {
+ pr_debug("%s(0x%p)\n", __FUNCTION__, ptr);
+
+ spin_lock(&memleak_lock);
+ make_black_pointer((unsigned long)ptr);
+ spin_unlock(&memleak_lock);
+
+ cpu_clear(cpu_id, memleak_cpu_mask);
+ }
+
+ out:
+ local_irq_restore(flags);
+}
+EXPORT_SYMBOL(memleak_debug_ignore);
+
+/* Add a scanning area to a pointer */
+void memleak_debug_scan_area(const void *ptr, unsigned long offset, size_t length)
+{
+ unsigned long flags;
+ unsigned int cpu_id = smp_processor_id();
+
+ if (!ptr)
+ return;
+
+ local_irq_save(flags);
+
+ if (!memleak_initialized) {
+ struct memleak_preinit_pointer *pointer;
+
+ BUG_ON(cpu_id != 0);
+
+ if (preinit_pos >= PREINIT_POINTERS)
+ panic("kmemleak: preinit pointers buffer overflow\n");
+ pointer = &preinit_pointers[preinit_pos++];
+
+ pointer->type = MEMLEAK_SCAN_AREA;
+ pointer->pointer = ptr;
+ pointer->offset = offset;
+ pointer->size = length;
+
+ goto out;
+ }
+
+ /* avoid recursive calls. See memleak_debug_alloc() for an explanation */
+ if (!cpu_test_and_set(cpu_id, memleak_cpu_mask)) {
+ pr_debug("%s(0x%p)\n", __FUNCTION__, ptr);
+
+ spin_lock(&memleak_lock);
+ add_scan_area((unsigned long)ptr, offset, length);
+ spin_unlock(&memleak_lock);
+
+ cpu_clear(cpu_id, memleak_cpu_mask);
+ }
+
+ out:
+ local_irq_restore(flags);
+}
+EXPORT_SYMBOL(memleak_debug_scan_area);
+
+/* Scan a block of memory (exclusive range) for pointers and move
+ * those found to the gray list
+ */
+static void memleak_scan_block(void *_start, void *_end)
+{
+ unsigned long *ptr;
+ unsigned long *start = (unsigned long *)ALIGN((unsigned long)_start,
+ BYTES_PER_WORD);
+ unsigned long *end = _end;
+
+ for (ptr = start; ptr < end; ptr++) {
+ struct memleak_pointer *pointer =
+ radix_tree_lookup(&pointer_tree,
+ (*ptr) & ~(BYTES_PER_WORD - 1));
+ if (!pointer)
+ continue;
+ if (!COLOR_WHITE(pointer))
+ continue;
+
+ pointer->count++;
+ if (COLOR_GRAY(pointer))
+ list_add_tail_rcu(&pointer->gray_list, &gray_list);
+ }
+}
+
+/* Scan a memory block represented by a memleak_pointer */
+static inline void memleak_scan_pointer(struct memleak_pointer *pointer)
+{
+ struct memleak_scan_area *area;
+ struct hlist_node *elem;
+
+ if (hlist_empty(&pointer->area_list))
+ memleak_scan_block((void *)pointer->pointer,
+ (void *)(pointer->pointer + pointer->size));
+ else
+ hlist_for_each_entry(area, elem, &pointer->area_list, node) {
+ unsigned long ptr = pointer->pointer + area->offset;
+
+ memleak_scan_block((void *)ptr, (void *)(ptr + area->length));
+ }
+}
+
+/* Scan the memory and print the orphan pointers */
+static void memleak_scan(void)
+{
+ unsigned long flags;
+ struct memleak_pointer *pointer;
+#ifdef TASK_STACK_SCAN
+ struct task_struct *task;
+#endif
+ int i;
+
+ spin_lock_irqsave(&memleak_lock, flags);
+
+ list_for_each_entry_rcu(pointer, &pointer_list, pointer_list) {
+ pointer->count = 0;
+ if (COLOR_GRAY(pointer))
+ list_add_tail_rcu(&pointer->gray_list, &gray_list);
+ }
+
+ /* data/bss scanning */
+ memleak_scan_block(_sdata, _edata);
+ memleak_scan_block(__bss_start, __bss_stop);
+
+#ifdef CONFIG_SMP
+ /* per-cpu scanning */
+ for (i = 0; i < NR_CPUS; i++)
+ memleak_scan_block(__per_cpu_offset[i] + __per_cpu_start,
+ __per_cpu_offset[i] + __per_cpu_end);
+#endif
+
+ /* mem_map scanning */
+ for_each_online_node(i) {
+ struct page *page, *end;
+
+ page = NODE_MEM_MAP(i);
+ end = page + NODE_DATA(i)->node_spanned_pages;
+
+ memleak_scan_block(page, end);
+ }
+
+#ifdef TASK_STACK_SCAN
+ for_each_process(task)
+ memleak_scan_block(task_stack_page(task),
+ task_stack_page(task) + THREAD_SIZE);
+#endif
+
+ /* gray_list scanning */
+ list_for_each_entry_rcu(pointer, &gray_list, gray_list) {
+ memleak_scan_pointer(pointer);
+ list_del_rcu(&pointer->gray_list);
+ }
+
+ spin_unlock_irqrestore(&memleak_lock, flags);
+}
+
+#ifdef CONFIG_DEBUG_FS
+static void *memleak_seq_start(struct seq_file *seq, loff_t *pos)
+{
+ struct memleak_pointer *pointer;
+ loff_t n = *pos;
+
+ mutex_lock(&memleak_mutex);
+
+ if (!n)
+ memleak_scan();
+
+ list_for_each_entry_rcu(pointer, &pointer_list, pointer_list) {
+ if (!n--)
+ return pointer;
+ }
+
+ return NULL;
+}
+
+static void *memleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+ struct list_head *n = ((struct memleak_pointer *)v)->pointer_list.next;
+
+ ++(*pos);
+
+ if (n != &pointer_list)
+ return list_entry(n, struct memleak_pointer, pointer_list);
+ return NULL;
+}
+
+static void memleak_seq_stop(struct seq_file *seq, void *v)
+{
+ mutex_unlock(&memleak_mutex);
+}
+
+static int memleak_seq_show(struct seq_file *seq, void *v)
+{
+ const struct memleak_pointer *pointer = v;
+#ifdef CONFIG_KALLSYMS
+ char namebuf[KSYM_NAME_LEN + 1] = "";
+ char *modname;
+ unsigned long symsize;
+ unsigned long offset = 0;
+#endif
+ int i;
+
+ if (!COLOR_WHITE(pointer))
+ return 0;
+
+ seq_printf(seq, "orphan pointer 0x%08lx (size %d):\n",
+ pointer->pointer, pointer->size);
+
+ for (i = 0; i < MAX_TRACE; i++) {
+ unsigned long trace = pointer->trace[i];
+ if (!trace)
+ break;
+
+#ifdef CONFIG_KALLSYMS
+ kallsyms_lookup(trace, &symsize, &offset, &modname, namebuf);
+ seq_printf(seq, " %lx: <%s>\n", trace, namebuf);
+#else
+ seq_printf(seq, " %lx\n", trace);
+#endif
+ }
+
+ return 0;
+}
+
+static struct seq_operations memleak_seq_ops = {
+ .start = memleak_seq_start,
+ .next = memleak_seq_next,
+ .stop = memleak_seq_stop,
+ .show = memleak_seq_show,
+};
+
+static int memleak_seq_open(struct inode *inode, struct file *file)
+{
+ return seq_open(file, &memleak_seq_ops);
+}
+
+static struct file_operations memleak_fops = {
+ .owner = THIS_MODULE,
+ .open = memleak_seq_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = seq_release,
+};
+#endif /* CONFIG_DEBUG_FS */
+
+/* KMemLeak initialization. Set up the radix tree for the pointer aliases */
+void __init memleak_debug_init(void)
+{
+ struct memleak_offset *ml_off;
+ int i = 0;
+ unsigned long flags;
+
+ pointer_cache = kmem_cache_create("pointer_cache", sizeof(struct memleak_pointer),
+ 0, SLAB_PANIC, NULL, NULL);
+ if (!pointer_cache)
+ panic("kmemleak: cannot create the pointer cache\n");
+
+ /* no need to hold the spinlock as SMP is not initialized yet
+ * and memleak_initialized is 0 */
+
+ /* primary aliases - container_of(member) */
+ for (ml_off = __memleak_offsets_start; ml_off < __memleak_offsets_end; ml_off++)
+ if (!insert_alias(ml_off->size, ml_off->offset))
+ i++;
+ pr_debug("kmemleak: found %d primary aliases\n", i);
+
+ /* secondary aliases - container_of(container_of(member)) */
+ for (ml_off = __memleak_offsets_start; ml_off < __memleak_offsets_end; ml_off++) {
+ struct hlist_head *alias_list;
+ struct memleak_alias *alias;
+ struct hlist_node *elem;
+
+ alias_list = radix_tree_lookup(&alias_tree, ml_off->member_size);
+ if (!alias_list)
+ continue;
+
+ hlist_for_each_entry(alias, elem, alias_list, node)
+ if (!insert_alias(ml_off->size, ml_off->offset + alias->offset))
+ i++;
+ }
+ pr_debug("kmemleak: found %d aliases\n", i);
+ pr_debug("kmemleak: %d preinit actions\n", preinit_pos);
+
+ local_irq_save(flags);
+
+ memleak_initialized = 1;
+
+ /* execute the buffered memleak actions */
+ for (i = 0; i < preinit_pos; i++) {
+ struct memleak_preinit_pointer *pointer = &preinit_pointers[i];
+
+ switch (pointer->type) {
+ case MEMLEAK_ALLOC:
+ memleak_debug_alloc(pointer->pointer, pointer->size,
+ pointer->ref_count);
+ break;
+ case MEMLEAK_FREE:
+ memleak_debug_free(pointer->pointer);
+ break;
+ case MEMLEAK_RESIZE:
+ memleak_debug_resize(pointer->pointer, pointer->size);
+ break;
+ case MEMLEAK_NOT_LEAK:
+ memleak_debug_not_leak(pointer->pointer);
+ break;
+ case MEMLEAK_IGNORE:
+ memleak_debug_ignore(pointer->pointer);
+ break;
+ case MEMLEAK_SCAN_AREA:
+ memleak_debug_scan_area(pointer->pointer,
+ pointer->offset, pointer->size);
+ break;
+ default:
+ BUG();
+ }
+ }
+
+ local_irq_restore(flags);
+
+ printk(KERN_INFO "Kernel memory leak detector initialized\n");
+}
+
+/* Late initialization function */
+int __init memleak_late_init(void)
+{
+#ifdef CONFIG_DEBUG_FS
+ struct dentry *dentry;
+
+ dentry = debugfs_create_file("memleak", S_IRUGO, NULL, NULL,
+ &memleak_fops);
+ if (!dentry)
+ return -ENOMEM;
+#endif
+ pr_debug("kmemleak: late initialization completed\n");
+
+ return 0;
+}
+late_initcall(memleak_late_init);
From: Catalin Marinas <[email protected]>
There are allocations for which the main pointer cannot be found but they
are not memory leaks. This patch fixes some of them.
Signed-off-by: Catalin Marinas <[email protected]>
---
arch/i386/kernel/setup.c | 1 +
ipc/util.c | 2 ++
kernel/module.c | 2 ++
kernel/params.c | 7 +++++--
4 files changed, 10 insertions(+), 2 deletions(-)
diff --git a/arch/i386/kernel/setup.c b/arch/i386/kernel/setup.c
index 846e163..a6407f6 100644
--- a/arch/i386/kernel/setup.c
+++ b/arch/i386/kernel/setup.c
@@ -1323,6 +1323,7 @@ legacy_init_iomem_resources(struct resou
if (e820.map[i].addr + e820.map[i].size > 0x100000000ULL)
continue;
res = kzalloc(sizeof(struct resource), GFP_ATOMIC);
+ memleak_debug_not_leak(res);
switch (e820.map[i].type) {
case E820_RAM: res->name = "System RAM"; break;
case E820_ACPI: res->name = "ACPI Tables"; break;
diff --git a/ipc/util.c b/ipc/util.c
index 8193299..40014a4 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -389,6 +389,7 @@ void* ipc_rcu_alloc(int size)
*/
if (rcu_use_vmalloc(size)) {
out = vmalloc(HDRLEN_VMALLOC + size);
+ memleak_debug_not_leak(out);
if (out) {
out += HDRLEN_VMALLOC;
container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 1;
@@ -396,6 +397,7 @@ void* ipc_rcu_alloc(int size)
}
} else {
out = kmalloc(HDRLEN_KMALLOC + size, GFP_KERNEL);
+ memleak_debug_not_leak(out);
if (out) {
out += HDRLEN_KMALLOC;
container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 0;
diff --git a/kernel/module.c b/kernel/module.c
index 9b400dc..1c9f04e 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1576,6 +1576,7 @@ #endif
/* Do the allocs. */
ptr = module_alloc(mod->core_size);
+ memleak_debug_not_leak(ptr);
if (!ptr) {
err = -ENOMEM;
goto free_percpu;
@@ -1584,6 +1585,7 @@ #endif
mod->module_core = ptr;
ptr = module_alloc(mod->init_size);
+ memleak_debug_ignore(ptr);
if (!ptr && mod->init_size) {
err = -ENOMEM;
goto free_core;
diff --git a/kernel/params.c b/kernel/params.c
index af43ecd..6c04a68 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -548,6 +548,7 @@ static void __init kernel_param_sysfs_se
unsigned int name_skip)
{
struct module_kobject *mk;
+ struct module_param_attrs *mp;
mk = kzalloc(sizeof(struct module_kobject), GFP_KERNEL);
BUG_ON(!mk);
@@ -557,11 +558,13 @@ static void __init kernel_param_sysfs_se
kobject_set_name(&mk->kobj, name);
kobject_register(&mk->kobj);
+ mp = param_sysfs_setup(mk, kparam, num_params, name_skip);
/* no need to keep the kobject if no parameter is exported */
- if (!param_sysfs_setup(mk, kparam, num_params, name_skip)) {
+ if (!mp) {
kobject_unregister(&mk->kobj);
kfree(mk);
- }
+ } else
+ memleak_debug_not_leak(mp);
}
/*
From: Catalin Marinas <[email protected]>
This patch only contains some very simple testing at the moment. Proper
testing will be needed.
Signed-off-by: Catalin Marinas <[email protected]>
---
lib/Kconfig.debug | 9 +++++++++
mm/Makefile | 1 +
mm/memleak-test.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 64 insertions(+), 0 deletions(-)
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 821565a..d0404e2 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -122,6 +122,15 @@ config DEBUG_MEMLEAK_PREINIT_POINTERS
buffer will be freed once the system initialization is
completed.
+config DEBUG_MEMLEAK_TEST
+ tristate "Test the kernel memory leak detector"
+ default n
+ depends on DEBUG_MEMLEAK
+ help
+ Say Y here to build the test harness for the kernel memory
+ leak detector. At the moment, this option enables a module
+ that explicitly leaks memory.
+
config DEBUG_PREEMPT
bool "Debug preemptible kernel"
depends on DEBUG_KERNEL && PREEMPT
diff --git a/mm/Makefile b/mm/Makefile
index d487d96..aef1bd8 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -24,3 +24,4 @@ obj-$(CONFIG_MEMORY_HOTPLUG) += memory_h
obj-$(CONFIG_FS_XIP) += filemap_xip.o
obj-$(CONFIG_MIGRATION) += migrate.o
obj-$(CONFIG_DEBUG_MEMLEAK) += memleak.o
+obj-$(CONFIG_DEBUG_MEMLEAK_TEST) += memleak-test.o
diff --git a/mm/memleak-test.c b/mm/memleak-test.c
new file mode 100644
index 0000000..15ddd36
--- /dev/null
+++ b/mm/memleak-test.c
@@ -0,0 +1,54 @@
+/*
+ * mm/memleak-test.c
+ *
+ * Copyright (C) 2006 ARM Limited
+ * Written by Catalin Marinas <[email protected]>
+ *
+ * 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/memleak.h>
+
+/* Some very simple testing. This function needs to be extended for
+ * proper testing */
+static int __init memleak_test_init(void)
+{
+ printk(KERN_INFO "KMemLeak testing\n");
+
+ /* make some orphan pointers */
+ kmalloc(32, GFP_KERNEL);
+ kmalloc(32, GFP_KERNEL);
+#ifndef CONFIG_MODULES
+ kmem_cache_alloc(files_cachep, GFP_KERNEL);
+ kmem_cache_alloc(files_cachep, GFP_KERNEL);
+#endif
+ vmalloc(64);
+ vmalloc(64);
+
+ return 0;
+}
+module_init(memleak_test_init);
+
+static void __exit memleak_test_exit(void)
+{
+}
+module_exit(memleak_test_exit);
+
+MODULE_LICENSE("GPL");
From: Catalin Marinas <[email protected]>
Signed-off-by: Catalin Marinas <[email protected]>
---
Documentation/kmemleak.txt | 92 ++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 92 insertions(+), 0 deletions(-)
diff --git a/Documentation/kmemleak.txt b/Documentation/kmemleak.txt
new file mode 100644
index 0000000..7072325
--- /dev/null
+++ b/Documentation/kmemleak.txt
@@ -0,0 +1,92 @@
+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 pointers are not freed but only
+reported via /sys/kernel/debug/memleak. A similar method is used by
+the Valgrind tool (memcheck --leak-check) to detect the memory leaks
+in user-space applications.
+
+
+Basic Algorithm
+---------------
+
+The memory allocations via kmalloc, vmalloc, kmem_cache_alloc and
+friends are tracked and the pointers, together with additional
+information like size and stack trace, are stored in a radix tree. The
+corresponding freeing function calls are tracked and the pointers
+removed from the radix tree.
+
+An allocated block of memory is considered orphan if a pointer to its
+start address or to an alias (pointer aliases are explained later)
+cannot 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 leak.
+
+The scanning algorithm steps:
+
+ 1. mark all pointers as white (remaining white pointers 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 radix
+ tree. If a white pointer is found, it is added to the grey list
+ 3. scan the grey pointers for matching addresses (some white
+ pointers can become grey and added at the end of the grey list)
+ until the grey set is finished
+ 4. the remaining white pointers are considered orphan and reported
+ via /sys/kernel/debug/memleak
+
+
+Improvements
+------------
+
+Because the Linux kernel calculates many pointers at run-time via the
+container_of macro (see the lists implementation), a lot of false
+positives would be reported. This tool re-writes the container_of
+macro so that the offset and size information is stored in the
+.init.memleak_offsets section. The memleak_init() function creates a
+radix tree with corresponding offsets for every encountered block
+size. The memory allocations hook stores the pointer address together
+with its aliases based on the size of the allocated block.
+
+While one level of offsets should be enough for most cases, two levels
+are considered, i.e. container_of(container_of(...)) (one false
+positive is the "struct socket_alloc" allocation in the
+sock_alloc_inode() function).
+
+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 equal to the
+pointer (or aliases) that need to be found so that the block is not
+considered a leak. One example is __vmalloc().
+
+
+Limitations and Drawbacks
+-------------------------
+
+The biggest 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/memleak file is read. Anyway,
+this tool is intended for debugging purposes where the performance
+might not be the most important requirement.
+
+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
+container_of macro or the pointer is stored in a location not scanned
+by kmemleak. If the "member" argument in the offsetof(type, member)
+call is not constant, kmemleak considers the offset as zero since it
+cannot be determined at compilation time (as a side node, it seems
+that gcc-4.0 doesn't compile these offsetof constructs either).
+
+Page allocations and ioremap are not tracked. NUMA architectures are
+not supported yet.
+
+Only the ARM and i386 architectures are currently supported.
From: Catalin Marinas <[email protected]>
This patch adds the callbacks to memleak_(alloc|free) functions from
kmalloc/kree, kmem_cache_(alloc|free), vmalloc/vfree etc.
Signed-off-by: Catalin Marinas <[email protected]>
---
drivers/base/platform.c | 1 +
include/linux/slab.h | 4 ++++
kernel/module.c | 18 ++++++++++++++++++
mm/page_alloc.c | 2 ++
mm/slab.c | 31 +++++++++++++++++++++++++++----
mm/vmalloc.c | 24 ++++++++++++++++++++++--
6 files changed, 74 insertions(+), 6 deletions(-)
diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 83f5c59..824d447 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -166,6 +166,7 @@ struct platform_device *platform_device_
struct platform_object *pa;
pa = kzalloc(sizeof(struct platform_object) + strlen(name), GFP_KERNEL);
+ memleak_debug_resize(pa, sizeof(struct platform_object));
if (pa) {
strcpy(pa->name, name);
pa->pdev.name = pa->name;
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 2d985d5..aa37216 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -89,6 +89,7 @@ #endif
static inline void *kmalloc(size_t size, gfp_t flags)
{
+#ifndef CONFIG_DEBUG_MEMLEAK
if (__builtin_constant_p(size)) {
int i = 0;
#define CACHE(x) \
@@ -107,6 +108,7 @@ found:
malloc_sizes[i].cs_dmacachep :
malloc_sizes[i].cs_cachep, flags);
}
+#endif
return __kmalloc(size, flags);
}
@@ -114,6 +116,7 @@ extern void *__kzalloc(size_t, gfp_t);
static inline void *kzalloc(size_t size, gfp_t flags)
{
+#ifndef CONFIG_DEBUG_MEMLEAK
if (__builtin_constant_p(size)) {
int i = 0;
#define CACHE(x) \
@@ -132,6 +135,7 @@ found:
malloc_sizes[i].cs_dmacachep :
malloc_sizes[i].cs_cachep, flags);
}
+#endif
return __kzalloc(size, flags);
}
diff --git a/kernel/module.c b/kernel/module.c
index bbe0486..9b400dc 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1413,6 +1413,9 @@ static struct module *load_module(void _
exportindex, modindex, obsparmindex, infoindex, gplindex,
crcindex, gplcrcindex, versindex, pcpuindex, gplfutureindex,
gplfuturecrcindex;
+#ifdef CONFIG_DEBUG_MEMLEAK
+ unsigned int dataindex, bssindex;
+#endif
struct module *mod;
long err = 0;
void *percpu = NULL, *ptr = NULL; /* Stops spurious gcc warning */
@@ -1510,6 +1513,10 @@ #ifdef CONFIG_KALLSYMS
sechdrs[symindex].sh_flags |= SHF_ALLOC;
sechdrs[strindex].sh_flags |= SHF_ALLOC;
#endif
+#ifdef CONFIG_DEBUG_MEMLEAK
+ dataindex = find_sec(hdr, sechdrs, secstrings, ".data");
+ bssindex = find_sec(hdr, sechdrs, secstrings, ".bss");
+#endif
/* Check module struct version now, before we try to use module. */
if (!check_modstruct_version(sechdrs, versindex, mod)) {
@@ -1608,6 +1615,17 @@ #endif
/* Module has been moved. */
mod = (void *)sechdrs[modindex].sh_addr;
+ /* only scan the sections containing data */
+ memleak_debug_scan_area(mod->module_core,
+ (unsigned long)mod - (unsigned long)mod->module_core,
+ sizeof(struct module));
+ memleak_debug_scan_area(mod->module_core,
+ sechdrs[dataindex].sh_addr - (unsigned long)mod->module_core,
+ sechdrs[dataindex].sh_size);
+ memleak_debug_scan_area(mod->module_core,
+ sechdrs[bssindex].sh_addr - (unsigned long)mod->module_core,
+ sechdrs[bssindex].sh_size);
+
/* Now we've moved module, initialize linked lists, etc. */
module_unload_init(mod);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 253a450..b33114e 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2800,6 +2800,8 @@ void *__init alloc_large_system_hash(con
if (_hash_mask)
*_hash_mask = (1 << log2qty) - 1;
+ memleak_debug_alloc(table, size, 1);
+
return table;
}
diff --git a/mm/slab.c b/mm/slab.c
index d31a06b..cd30c85 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -434,6 +434,8 @@ #if DEBUG
* variables contain the offset to the user object and its size.
*/
int obj_offset;
+#endif
+#if DEBUG || defined(CONFIG_DEBUG_MEMLEAK)
int obj_size;
#endif
};
@@ -672,7 +674,7 @@ static struct kmem_cache cache_cache = {
.shared = 1,
.buffer_size = sizeof(struct kmem_cache),
.name = "kmem_cache",
-#if DEBUG
+#if DEBUG || defined(CONFIG_DEBUG_MEMLEAK)
.obj_size = sizeof(struct kmem_cache),
#endif
};
@@ -2042,9 +2044,11 @@ #endif
if (!cachep)
goto oops;
-#if DEBUG
+#if DEBUG || defined(CONFIG_DEBUG_MEMLEAK)
cachep->obj_size = size;
+#endif
+#if DEBUG
if (flags & SLAB_RED_ZONE) {
/* redzoning only works with word aligned caches */
align = BYTES_PER_WORD;
@@ -2879,6 +2883,7 @@ #endif
STATS_INC_ALLOCMISS(cachep);
objp = cache_alloc_refill(cachep, flags);
}
+ memleak_debug_erase(ac->entry[ac->avail]);
return objp;
}
@@ -3144,7 +3149,11 @@ #endif
*/
void *kmem_cache_alloc(struct kmem_cache *cachep, gfp_t flags)
{
- return __cache_alloc(cachep, flags, __builtin_return_address(0));
+ void *ptr = __cache_alloc(cachep, flags, __builtin_return_address(0));
+
+ memleak_debug_alloc(ptr, cachep->obj_size, 1);
+
+ return ptr;
}
EXPORT_SYMBOL(kmem_cache_alloc);
@@ -3159,6 +3168,9 @@ EXPORT_SYMBOL(kmem_cache_alloc);
void *kmem_cache_zalloc(struct kmem_cache *cache, gfp_t flags)
{
void *ret = __cache_alloc(cache, flags, __builtin_return_address(0));
+
+ memleak_debug_alloc(ret, cache->obj_size, 1);
+
if (ret)
memset(ret, 0, obj_size(cache));
return ret;
@@ -3280,6 +3292,7 @@ static __always_inline void *__do_kmallo
void *caller)
{
struct kmem_cache *cachep;
+ void *ptr;
/* If you want to save a few bytes .text space: replace
* __ with kmem_.
@@ -3289,7 +3302,11 @@ static __always_inline void *__do_kmallo
cachep = __find_general_cachep(size, flags);
if (unlikely(cachep == NULL))
return NULL;
- return __cache_alloc(cachep, flags, caller);
+ ptr = __cache_alloc(cachep, flags, caller);
+
+ memleak_debug_alloc(ptr, size, 1);
+
+ return ptr;
}
@@ -3345,6 +3362,7 @@ void *__alloc_percpu(size_t size)
memset(pdata->ptrs[i], 0, size);
}
+ memleak_debug_not_leak(pdata);
/* Catch derefs w/o wrappers */
return (void *)(~(unsigned long)pdata);
@@ -3373,6 +3391,9 @@ void kmem_cache_free(struct kmem_cache *
unsigned long flags;
local_irq_save(flags);
+
+ memleak_debug_free(objp);
+
__cache_free(cachep, objp);
local_irq_restore(flags);
}
@@ -3396,6 +3417,8 @@ void kfree(const void *objp)
return;
local_irq_save(flags);
kfree_debugcheck(objp);
+ memleak_debug_free(objp);
+
c = virt_to_cache(objp);
mutex_debug_check_no_locks_freed(objp, obj_size(c));
__cache_free(c, (void *)objp);
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index c0504f1..5197492 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -349,6 +349,9 @@ void __vunmap(void *addr, int deallocate
void vfree(void *addr)
{
BUG_ON(in_interrupt());
+
+ memleak_debug_free(addr);
+
__vunmap(addr, 1);
}
EXPORT_SYMBOL(vfree);
@@ -447,7 +450,14 @@ fail:
void *__vmalloc_area(struct vm_struct *area, gfp_t gfp_mask, pgprot_t prot)
{
- return __vmalloc_area_node(area, gfp_mask, prot, -1);
+ void *addr = __vmalloc_area_node(area, gfp_mask, prot, -1);
+
+ /* this needs ref_count = 2 since vm_struct also contains a
+ pointer to this address. The guard page is also subtracted
+ from the size */
+ memleak_debug_alloc(addr, area->size - PAGE_SIZE, 2);
+
+ return addr;
}
/**
@@ -466,6 +476,10 @@ void *__vmalloc_node(unsigned long size,
int node)
{
struct vm_struct *area;
+ void *addr;
+#ifdef CONFIG_DEBUG_MEMLEAK
+ unsigned long real_size = size;
+#endif
size = PAGE_ALIGN(size);
if (!size || (size >> PAGE_SHIFT) > num_physpages)
@@ -475,7 +489,13 @@ void *__vmalloc_node(unsigned long size,
if (!area)
return NULL;
- return __vmalloc_area_node(area, gfp_mask, prot, node);
+ addr = __vmalloc_area_node(area, gfp_mask, prot, node);
+
+ /* this needs ref_count = 2 since the vm_struct also contains
+ a pointer to this address */
+ memleak_debug_alloc(addr, real_size, 2);
+
+ return addr;
}
EXPORT_SYMBOL(__vmalloc_node);
From: Catalin Marinas <[email protected]>
This patch modifies the vmlinux.lds.S script and adds the backtrace support
for ARM to be used with kmemleak.
Signed-off-by: Catalin Marinas <[email protected]>
---
arch/arm/kernel/vmlinux.lds.S | 7 +++++++
include/asm-arm/processor.h | 12 ++++++++++++
2 files changed, 19 insertions(+), 0 deletions(-)
diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
index 2b254e8..c6f038c 100644
--- a/arch/arm/kernel/vmlinux.lds.S
+++ b/arch/arm/kernel/vmlinux.lds.S
@@ -68,6 +68,11 @@ #endif
__per_cpu_start = .;
*(.data.percpu)
__per_cpu_end = .;
+#ifdef CONFIG_DEBUG_MEMLEAK
+ __memleak_offsets_start = .;
+ *(.init.memleak_offsets)
+ __memleak_offsets_end = .;
+#endif
#ifndef CONFIG_XIP_KERNEL
__init_begin = _stext;
*(.init.data)
@@ -110,6 +115,7 @@ #endif
.data : AT(__data_loc) {
__data_start = .; /* address in memory */
+ _sdata = .;
/*
* first, the init task union, aligned
@@ -158,6 +164,7 @@ #endif
__bss_start = .; /* BSS */
*(.bss)
*(COMMON)
+ __bss_stop = .;
_end = .;
}
/* Stabs debugging sections. */
diff --git a/include/asm-arm/processor.h b/include/asm-arm/processor.h
index 04f4d34..feaf017 100644
--- a/include/asm-arm/processor.h
+++ b/include/asm-arm/processor.h
@@ -121,6 +121,18 @@ #define spin_lock_prefetch(x) do { } whi
#endif
+#ifdef CONFIG_FRAME_POINTER
+static inline unsigned long arch_call_address(void *frame)
+{
+ return *(unsigned long *) (frame - 4) - 4;
+}
+
+static inline void *arch_prev_frame(void *frame)
+{
+ return *(void **) (frame - 12);
+}
+#endif
+
#endif
#endif /* __ASM_ARM_PROCESSOR_H */
From: Catalin Marinas <[email protected]>
This patch modifies the vmlinux.lds.S script and adds the backtrace support
for i386 to be used with kmemleak.
Signed-off-by: Catalin Marinas <[email protected]>
---
arch/i386/kernel/vmlinux.lds.S | 4 ++++
include/asm-i386/processor.h | 12 ++++++++++++
2 files changed, 16 insertions(+), 0 deletions(-)
diff --git a/arch/i386/kernel/vmlinux.lds.S b/arch/i386/kernel/vmlinux.lds.S
index 8831303..370480e 100644
--- a/arch/i386/kernel/vmlinux.lds.S
+++ b/arch/i386/kernel/vmlinux.lds.S
@@ -38,6 +38,7 @@ SECTIONS
RODATA
/* writeable */
+ _sdata = .; /* Start of data section */
.data : AT(ADDR(.data) - LOAD_OFFSET) { /* Data */
*(.data)
CONSTRUCTORS
@@ -140,6 +141,9 @@ SECTIONS
__per_cpu_start = .;
.data.percpu : AT(ADDR(.data.percpu) - LOAD_OFFSET) { *(.data.percpu) }
__per_cpu_end = .;
+ __memleak_offsets_start = .;
+ .init.memleak_offsets : AT(ADDR(.init.memleak_offsets) - LOAD_OFFSET) { *(.init.memleak_offsets) }
+ __memleak_offsets_end = .;
. = ALIGN(4096);
__init_end = .;
/* freed after init ends here */
diff --git a/include/asm-i386/processor.h b/include/asm-i386/processor.h
index 805f0dc..9b6568a 100644
--- a/include/asm-i386/processor.h
+++ b/include/asm-i386/processor.h
@@ -743,4 +743,16 @@ #else
#define mcheck_init(c) do {} while(0)
#endif
+#ifdef CONFIG_FRAME_POINTER
+static inline unsigned long arch_call_address(void *frame)
+{
+ return *(unsigned long *) (frame + 4);
+}
+
+static inline void *arch_prev_frame(void *frame)
+{
+ return *(void **) frame;
+}
+#endif
+
#endif /* __ASM_I386_PROCESSOR_H */
On 30/05/06, Catalin Marinas <[email protected]> wrote:
> This is a new version (0.3) of the kernel memory leak detector.
I forgot to mention - the kernels with this patch and the config
option enabled cannot be compiled with gcc4 because of a compiler bug
that always returns "true" for __builtin_constant_p(), even if its
argument can only be determined at run-time. This causes a few
compilation errors on the container_of usage.
--
Catalin