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    Subject[PATCH 01/15] kmemleak: Add the base support
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    Date
    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 unreferenced objects are not freed but only shown in
    /sys/kernel/debug/memleak. Enabling this feature introduces an
    overhead to memory allocations.

    Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
    Cc: Ingo Molnar <mingo@elte.hu>
    ---
    include/linux/memleak.h | 87 ++++
    init/main.c | 4
    mm/memleak.c | 1019 +++++++++++++++++++++++++++++++++++++++++++++++
    3 files changed, 1109 insertions(+), 1 deletions(-)
    create mode 100644 include/linux/memleak.h
    create mode 100644 mm/memleak.c

    diff --git a/include/linux/memleak.h b/include/linux/memleak.h
    new file mode 100644
    index 0000000..2756a05
    --- /dev/null
    +++ b/include/linux/memleak.h
    @@ -0,0 +1,87 @@
    +/*
    + * include/linux/memleak.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 __MEMLEAK_H
    +#define __MEMLEAK_H
    +
    +#ifdef CONFIG_DEBUG_MEMLEAK
    +
    +extern void memleak_init(void);
    +extern void memleak_alloc(const void *ptr, size_t size, int ref_count);
    +extern void memleak_free(const void *ptr);
    +extern void memleak_padding(const void *ptr, unsigned long offset, size_t size);
    +extern void memleak_not_leak(const void *ptr);
    +extern void memleak_ignore(const void *ptr);
    +extern void memleak_scan_area(const void *ptr, unsigned long offset, size_t length);
    +
    +static inline void memleak_alloc_recursive(const void *ptr, size_t size,
    + int ref_count, unsigned long flags)
    +{
    + if (!(flags & SLAB_NOLEAKTRACE))
    + memleak_alloc(ptr, size, ref_count);
    +}
    +
    +static inline void memleak_free_recursive(const void *ptr, unsigned long flags)
    +{
    + if (!(flags & SLAB_NOLEAKTRACE))
    + memleak_free(ptr);
    +}
    +
    +static inline void memleak_erase(void **ptr)
    +{
    + *ptr = NULL;
    +}
    +
    +#else
    +
    +#define DECLARE_MEMLEAK_OFFSET(name, type, member)
    +
    +static inline void memleak_init(void)
    +{
    +}
    +static inline void memleak_alloc(const void *ptr, size_t size, int ref_count)
    +{
    +}
    +static inline void memleak_alloc_recursive(const void *ptr, size_t size,
    + int ref_count, unsigned long flags)
    +{
    +}
    +static inline void memleak_free(const void *ptr)
    +{
    +}
    +static inline void memleak_free_recursive(const void *ptr, unsigned long flags)
    +{
    +}
    +static inline void memleak_not_leak(const void *ptr)
    +{
    +}
    +static inline void memleak_ignore(const void *ptr)
    +{
    +}
    +static inline void memleak_scan_area(const void *ptr, unsigned long offset, size_t length)
    +{
    +}
    +static inline void memleak_erase(void **ptr)
    +{
    +}
    +
    +#endif /* CONFIG_DEBUG_MEMLEAK */
    +
    +#endif /* __MEMLEAK_H */
    diff --git a/init/main.c b/init/main.c
    index 7e117a2..81cbbb7 100644
    --- a/init/main.c
    +++ b/init/main.c
    @@ -56,6 +56,7 @@
    #include <linux/debug_locks.h>
    #include <linux/debugobjects.h>
    #include <linux/lockdep.h>
    +#include <linux/memleak.h>
    #include <linux/pid_namespace.h>
    #include <linux/device.h>
    #include <linux/kthread.h>
    @@ -653,6 +654,8 @@ asmlinkage void __init start_kernel(void)
    enable_debug_pagealloc();
    cpu_hotplug_init();
    kmem_cache_init();
    + prio_tree_init();
    + memleak_init();
    debug_objects_mem_init();
    idr_init_cache();
    setup_per_cpu_pageset();
    @@ -662,7 +665,6 @@ 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)
    diff --git a/mm/memleak.c b/mm/memleak.c
    new file mode 100644
    index 0000000..1b09ca2
    --- /dev/null
    +++ b/mm/memleak.c
    @@ -0,0 +1,1019 @@
    +/*
    + * mm/memleak.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/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/kallsyms.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 <asm/sections.h>
    +#include <asm/processor.h>
    +#include <asm/thread_info.h>
    +#include <asm/atomic.h>
    +
    +#include <linux/memleak.h>
    +
    +/*
    + * Kmemleak configuration and common defines.
    + */
    +#define MAX_TRACE 16 /* stack trace length */
    +#define REPORTS_NR 100 /* maximum number of reported leaks */
    +#define MSECS_MIN_AGE 1000 /* minimum object age for leak reporting */
    +#undef SCAN_TASK_STACKS /* scan the task kernel stacks */
    +#undef REPORT_ORPHAN_FREEING /* notify when freeing orphan objects */
    +
    +#define BYTES_PER_WORD sizeof(void *)
    +#define MSECS_SCAN_YIELD 10
    +#define SECS_FIRST_SCAN 60
    +#define SECS_SCAN_PERIOD 600
    +
    +/* scanning area inside a memory block */
    +struct memleak_scan_area {
    + struct hlist_node node;
    + unsigned long offset;
    + size_t length;
    +};
    +
    +/* the main allocation tracking object */
    +struct memleak_object {
    + spinlock_t lock;
    + unsigned long flags;
    + struct list_head object_list;
    + struct list_head gray_list;
    + struct prio_tree_node tree_node;
    + struct rcu_head rcu; /* used for object_list lockless traversal */
    + atomic_t use_count; /* internal usage count */
    + unsigned long pointer;
    + size_t size;
    + int ref_count; /* the minimum encounters of the pointer */
    + int count; /* the ecounters of the pointer */
    + struct hlist_head area_list; /* areas to be scanned (or empty for all) */
    + 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 */
    +};
    +
    +/* The list of all allocated objects */
    +static LIST_HEAD(object_list);
    +static DEFINE_SPINLOCK(object_list_lock);
    +/* The list of the gray objects */
    +static LIST_HEAD(gray_list);
    +/* prio search tree for object boundaries */
    +static struct prio_tree_root object_tree_root;
    +static DEFINE_RWLOCK(object_tree_lock);
    +
    +/* allocation caches */
    +static struct kmem_cache *object_cache;
    +static struct kmem_cache *scan_area_cache;
    +
    +static atomic_t memleak_enabled = ATOMIC_INIT(0);
    +
    +/* minimum and maximum address that may be valid pointers */
    +static unsigned long min_addr = ~0;
    +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 DEFINE_MUTEX(scan_mutex);
    +static int reported_leaks;
    +static int scan_should_stop;
    +
    +static unsigned long jiffies_scan_yield;
    +static unsigned long jiffies_min_age;
    +
    +/*
    + * Early object allocation (before kmemleak is fully initialised).
    + */
    +#define EARLY_LOG_NR 200
    +
    +enum {
    + MEMLEAK_ALLOC,
    + MEMLEAK_FREE,
    + MEMLEAK_NOT_LEAK,
    + MEMLEAK_IGNORE,
    + MEMLEAK_SCAN_AREA,
    +};
    +
    +struct early_log {
    + int op_type; /* kmemleak operation type */
    + const void *ptr;
    + size_t size;
    + int ref_count;
    + unsigned long offset;
    + size_t length;
    +};
    +
    +static struct early_log __initdata early_log[EARLY_LOG_NR];
    +static int __initdata crt_early_log;
    +
    +/* object flags */
    +#define OBJECT_ALLOCATED (1 << 0)
    +#define OBJECT_REPORTED (1 << 1)
    +
    +/*
    + * Object colors, encoded with count and ref_count:
    + * - white - orphan object, 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).
    + * Newly created objects don't have any color (object->count == -1) before
    + * the next memory scan when they become white.
    + */
    +static inline int color_white(const struct memleak_object *object)
    +{
    + return object->count != -1 && object->count < object->ref_count;
    +}
    +
    +static inline int color_gray(const struct memleak_object *object)
    +{
    + return object->ref_count != -1 && object->count >= object->ref_count;
    +}
    +
    +static inline int color_black(const struct memleak_object *object)
    +{
    + return object->ref_count == -1;
    +}
    +
    +static inline int unreferenced_object(struct memleak_object *object)
    +{
    + if (color_white(object) &&
    + (object->flags & OBJECT_ALLOCATED) &&
    + time_is_before_eq_jiffies(object->jiffies + jiffies_min_age))
    + return 1;
    + else
    + return 0;
    +}
    +
    +#define print_seq(seq, x...) \
    +do { \
    + if (seq) \
    + seq_printf(seq, x); \
    + else \
    + pr_info(x); \
    +} while (0)
    +
    +static void print_unreferenced(struct seq_file *seq,
    + struct memleak_object *object)
    +{
    + char namebuf[KSYM_NAME_LEN + 1] = "";
    + char *modname;
    + unsigned long symsize;
    + unsigned long offset = 0;
    + int i;
    +
    + print_seq(seq, "unreferenced object 0x%08lx (size %zu):\n",
    + object->pointer, object->size);
    + print_seq(seq, " comm \"%s\", pid %d, jiffies %lu\n",
    + object->comm, object->pid, object->jiffies);
    + print_seq(seq, " backtrace:\n");
    +
    + for (i = 0; i < object->trace_len; i++) {
    + unsigned long trace = object->trace[i];
    +
    + kallsyms_lookup(trace, &symsize, &offset, &modname, namebuf);
    + print_seq(seq, " [<%08lx>] %s\n", trace, namebuf);
    + }
    +}
    +
    +static void dump_object_info(struct memleak_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(" ref_count = %d\n", object->ref_count);
    + pr_notice(" count = %d\n", object->count);
    + pr_notice(" backtrace:\n");
    + print_stack_trace(&trace, 4);
    +}
    +
    +static struct memleak_object *lookup_object(unsigned long ptr, int alias)
    +{
    + struct prio_tree_node *node;
    + struct prio_tree_iter iter;
    + struct memleak_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 memleak_object, tree_node);
    + if (!alias && object->pointer != ptr) {
    + pr_warning("kmemleak: found object by alias");
    + object = NULL;
    + }
    + } else
    + object = NULL;
    +
    + return object;
    +}
    +
    +/*
    + * Return 1 if successful or 0 otherwise.
    + */
    +static inline int get_object(struct memleak_object *object)
    +{
    + return atomic_inc_not_zero(&object->use_count);
    +}
    +
    +static void free_object_rcu(struct rcu_head *rcu)
    +{
    + struct hlist_node *elem, *tmp;
    + struct memleak_scan_area *area;
    + struct memleak_object *object =
    + container_of(rcu, struct memleak_object, rcu);
    +
    + /* once use_count is 0, there is no code accessing the object */
    + 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);
    +}
    +
    +static void put_object(struct memleak_object *object)
    +{
    + unsigned long flags;
    +
    + if (!atomic_dec_and_test(&object->use_count))
    + return;
    +
    + /* should only get here after delete_object was called */
    + BUG_ON(object->flags & OBJECT_ALLOCATED);
    +
    + spin_lock_irqsave(&object_list_lock, flags);
    + /* the last reference to this object */
    + list_del_rcu(&object->object_list);
    + call_rcu(&object->rcu, free_object_rcu);
    + spin_unlock_irqrestore(&object_list_lock, flags);
    +}
    +
    +static struct memleak_object *find_and_get_object(unsigned long ptr, int alias)
    +{
    + unsigned long flags;
    + struct memleak_object *object;
    +
    + read_lock_irqsave(&object_tree_lock, flags);
    + object = lookup_object(ptr, alias);
    + if (object)
    + get_object(object);
    + read_unlock_irqrestore(&object_tree_lock, flags);
    +
    + return object;
    +}
    +
    +/*
    + * Insert a pointer into the pointer hash table.
    + */
    +static inline void create_object(unsigned long ptr, size_t size, int ref_count)
    +{
    + unsigned long flags;
    + struct memleak_object *object;
    + struct prio_tree_node *node;
    + struct stack_trace trace;
    +
    + object = kmem_cache_alloc(object_cache, GFP_ATOMIC);
    + if (!object)
    + panic("kmemleak: cannot allocate a memleak_object structure\n");
    +
    + 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->ref_count = ref_count;
    + object->count = -1; /* black color initially */
    + object->jiffies = jiffies;
    + if (in_irq()) {
    + object->pid = 0;
    + strncpy(object->comm, "hardirq", TASK_COMM_LEN);
    + } else if (in_softirq()) {
    + object->pid = 0;
    + strncpy(object->comm, "softirq", TASK_COMM_LEN);
    + } else {
    + object->pid = current->pid;
    + strncpy(object->comm, current->comm, TASK_COMM_LEN);
    + }
    +
    + 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;
    +
    + if (ptr < min_addr)
    + min_addr = ptr;
    + if (ptr + size > max_addr)
    + max_addr = ptr + size;
    + /*
    + * Update the boundaries before inserting the object in the
    + * prio search tree.
    + */
    + smp_mb();
    +
    + write_lock_irqsave(&object_tree_lock, flags);
    + node = prio_tree_insert(&object_tree_root, &object->tree_node);
    + if (node != &object->tree_node) {
    + unsigned long flags;
    +
    + pr_warning("kmemleak: existing pointer\n");
    + dump_stack();
    +
    + object = lookup_object(ptr, 1);
    + spin_lock_irqsave(&object->lock, flags);
    + dump_object_info(object);
    + spin_unlock_irqrestore(&object->lock, flags);
    +
    + panic("kmemleak: cannot insert 0x%lx into the object search tree\n",
    + ptr);
    + }
    + write_unlock_irqrestore(&object_tree_lock, flags);
    +
    + spin_lock_irqsave(&object_list_lock, flags);
    + list_add_tail_rcu(&object->object_list, &object_list);
    + spin_unlock_irqrestore(&object_list_lock, flags);
    +}
    +
    +/*
    + * Remove a pointer from the pointer hash table.
    + */
    +static inline void delete_object(unsigned long ptr)
    +{
    + unsigned long flags;
    + struct memleak_object *object;
    +
    + write_lock_irqsave(&object_tree_lock, flags);
    + object = lookup_object(ptr, 0);
    + if (!object) {
    + pr_warning("kmemleak: freeing unknown object at 0x%08lx\n", ptr);
    + dump_stack();
    + write_unlock_irqrestore(&object_tree_lock, flags);
    + return;
    + }
    + prio_tree_remove(&object_tree_root, &object->tree_node);
    + write_unlock_irqrestore(&object_tree_lock, flags);
    +
    + BUG_ON(!(object->flags & OBJECT_ALLOCATED));
    +
    + spin_lock_irqsave(&object->lock, flags);
    + object->flags &= ~OBJECT_ALLOCATED;
    +#ifdef REPORT_ORPHAN_FREEING
    + if (color_white(object)) {
    + pr_warning("kmemleak: freeing orphan object 0x%08lx\n", ptr);
    + dump_stack();
    + dump_object_info(object);
    + }
    +#endif
    + object->pointer = 0;
    + spin_unlock_irqrestore(&object->lock, flags);
    +
    + put_object(object);
    +}
    +
    +/*
    + * Make a object permanently gray (false positive).
    + */
    +static inline void make_gray_object(unsigned long ptr)
    +{
    + unsigned long flags;
    + struct memleak_object *object;
    +
    + object = find_and_get_object(ptr, 0);
    + if (!object) {
    + dump_stack();
    + panic("kmemleak: graying unknown object at 0x%08lx\n", ptr);
    + }
    +
    + spin_lock_irqsave(&object->lock, flags);
    + object->ref_count = 0;
    + spin_unlock_irqrestore(&object->lock, flags);
    + put_object(object);
    +}
    +
    +/*
    + * Mark the object as black.
    + */
    +static inline void make_black_object(unsigned long ptr)
    +{
    + unsigned long flags;
    + struct memleak_object *object;
    +
    + object = find_and_get_object(ptr, 0);
    + if (!object) {
    + dump_stack();
    + panic("kmemleak: blacking unknown object at 0x%08lx\n", ptr);
    + }
    +
    + spin_lock_irqsave(&object->lock, flags);
    + object->ref_count = -1;
    + spin_unlock_irqrestore(&object->lock, flags);
    + put_object(object);
    +}
    +
    +/*
    + * Add a scanning area to the object.
    + */
    +static inline void add_scan_area(unsigned long ptr, unsigned long offset, size_t length)
    +{
    + unsigned long flags;
    + struct memleak_object *object;
    + struct memleak_scan_area *area;
    +
    + object = find_and_get_object(ptr, 0);
    + if (!object) {
    + dump_stack();
    + panic("kmemleak: adding scan area to unknown object at 0x%08lx\n", ptr);
    + }
    +
    + area = kmem_cache_alloc(scan_area_cache, GFP_ATOMIC);
    + if (!area)
    + panic("kmemleak: cannot allocate a scan area\n");
    +
    + spin_lock_irqsave(&object->lock, flags);
    + if (offset + length > object->size) {
    + dump_stack();
    + dump_object_info(object);
    + panic("kmemleak: scan area larger than object 0x%08lx\n", ptr);
    + }
    +
    + INIT_HLIST_NODE(&area->node);
    + area->offset = offset;
    + area->length = length;
    +
    + hlist_add_head(&area->node, &object->area_list);
    + spin_unlock_irqrestore(&object->lock, flags);
    + put_object(object);
    +}
    +
    +/*
    + * Log the early memleak_* calls.
    + */
    +static void __init memleak_early_log(int op_type, const void *ptr, size_t size,
    + int ref_count,
    + unsigned long offset, size_t length)
    +{
    + unsigned long flags;
    + struct early_log *log;
    +
    + if (crt_early_log >= EARLY_LOG_NR)
    + panic("kmemleak: early log buffer exceeded\n");
    +
    + local_irq_save(flags);
    + log = &early_log[crt_early_log];
    + log->op_type = op_type;
    + log->ptr = ptr;
    + log->size = size;
    + log->ref_count = ref_count;
    + log->offset = offset;
    + log->length = length;
    + crt_early_log++;
    + local_irq_restore(flags);
    +}
    +
    +/*
    + * Allocation function hook.
    + */
    +void memleak_alloc(const void *ptr, size_t size, int ref_count)
    +{
    + pr_debug("%s(0x%p, %zu, %d)\n", __FUNCTION__, ptr, size, ref_count);
    +
    + if (!atomic_read(&memleak_enabled)) {
    + memleak_early_log(MEMLEAK_ALLOC, ptr, size, ref_count, 0, 0);
    + return;
    + }
    + if (!ptr)
    + return;
    +
    + create_object((unsigned long)ptr, size, ref_count);
    +}
    +EXPORT_SYMBOL_GPL(memleak_alloc);
    +
    +/*
    + * Freeing function hook.
    + */
    +void memleak_free(const void *ptr)
    +{
    + pr_debug("%s(0x%p)\n", __FUNCTION__, ptr);
    +
    + if (!atomic_read(&memleak_enabled)) {
    + memleak_early_log(MEMLEAK_FREE, ptr, 0, 0, 0, 0);
    + return;
    + }
    + if (!ptr)
    + return;
    +
    + delete_object((unsigned long)ptr);
    +}
    +EXPORT_SYMBOL_GPL(memleak_free);
    +
    +/*
    + * Mark a object as a false positive.
    + */
    +void memleak_not_leak(const void *ptr)
    +{
    + pr_debug("%s(0x%p)\n", __FUNCTION__, ptr);
    +
    + if (!atomic_read(&memleak_enabled)) {
    + memleak_early_log(MEMLEAK_NOT_LEAK, ptr, 0, 0, 0, 0);
    + return;
    + }
    + if (!ptr)
    + return;
    +
    + make_gray_object((unsigned long)ptr);
    +}
    +EXPORT_SYMBOL(memleak_not_leak);
    +
    +/*
    + * Ignore this memory object.
    + */
    +void memleak_ignore(const void *ptr)
    +{
    + pr_debug("%s(0x%p)\n", __FUNCTION__, ptr);
    +
    + if (!atomic_read(&memleak_enabled)) {
    + memleak_early_log(MEMLEAK_IGNORE, ptr, 0, 0, 0, 0);
    + return;
    + }
    + if (!ptr)
    + return;
    +
    + make_black_object((unsigned long)ptr);
    +}
    +EXPORT_SYMBOL(memleak_ignore);
    +
    +/*
    + * Add a scanning area to an object.
    + */
    +void memleak_scan_area(const void *ptr, unsigned long offset, size_t length)
    +{
    + pr_debug("%s(0x%p)\n", __FUNCTION__, ptr);
    +
    + if (!atomic_read(&memleak_enabled)) {
    + memleak_early_log(MEMLEAK_SCAN_AREA, ptr, 0, 0, offset, length);
    + return;
    + }
    + if (!ptr)
    + return;
    +
    + add_scan_area((unsigned long)ptr, offset, length);
    +}
    +EXPORT_SYMBOL(memleak_scan_area);
    +
    +static inline void scan_yield(void)
    +{
    + BUG_ON(in_atomic());
    +
    + if (time_is_before_eq_jiffies(next_scan_yield)) {
    + schedule();
    + next_scan_yield = jiffies + jiffies_scan_yield;
    + }
    + if (signal_pending(current))
    + scan_should_stop = 1;
    +}
    +
    +/*
    + * Scan a block of memory (exclusive range) for pointers and move
    + * those found to the gray list.
    + */
    +static void scan_block(void *_start, void *_end, struct memleak_object *scanned)
    +{
    + unsigned long *ptr;
    + unsigned long *start = PTR_ALIGN(_start, BYTES_PER_WORD);
    + unsigned long *end = _end - (BYTES_PER_WORD - 1);
    +
    + for (ptr = start; ptr < end; ptr++) {
    + unsigned long flags;
    + unsigned long pointer = *ptr;
    + struct memleak_object *object;
    +
    + if (scan_should_stop)
    + break;
    +
    + /* If scanned, the CPU is yielded in the calling code */
    + if (!scanned)
    + scan_yield();
    +
    + /*
    + * The boundaries check doesn't need to be precise
    + * (hence no locking) since orphan objects need to
    + * pass a scanning threshold before being reported.
    + */
    + if (pointer < min_addr || pointer >= max_addr)
    + continue;
    +
    + object = find_and_get_object(pointer, 1);
    + if (!object)
    + continue;
    + if (object == scanned) {
    + /* self referenced */
    + 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;
    + }
    +
    + object->count++;
    + if (color_gray(object))
    + /* the object became gray, add it to the list */
    + list_add_tail(&object->gray_list, &gray_list);
    + else
    + put_object(object);
    + spin_unlock_irqrestore(&object->lock, flags);
    + }
    +}
    +
    +/*
    + * Scan a memory block represented by a memleak_object.
    + */
    +static inline void scan_object(struct memleak_object *object)
    +{
    + struct memleak_scan_area *area;
    + struct hlist_node *elem;
    + unsigned long flags;
    +
    + spin_lock_irqsave(&object->lock, flags);
    +
    + /* freed object */
    + if (!(object->flags & OBJECT_ALLOCATED))
    + 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 the memory and print the orphan objects.
    + */
    +static void memleak_scan(void)
    +{
    + unsigned long flags;
    + struct memleak_object *object, *tmp;
    + int i;
    +#ifdef SCAN_TASK_STACKS
    + struct task_struct *task;
    +#endif
    +
    + scan_should_stop = 0;
    +
    + 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 scanning */
    + for_each_possible_cpu(i)
    + scan_block(__per_cpu_start + per_cpu_offset(i),
    + __per_cpu_end + per_cpu_offset(i), NULL);
    +#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;
    +
    + scan_block(page, end, NULL);
    + }
    +
    +#ifdef SCAN_TASK_STACKS
    + 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);
    +#endif
    +
    + /*
    + * Scan the objects already referenced. 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
    + * memleak 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;
    + }
    + BUG_ON(!list_empty(&gray_list));
    +}
    +
    +static void *memleak_seq_start(struct seq_file *seq, loff_t *pos)
    +{
    + struct memleak_object *object;
    + loff_t n = *pos;
    +
    + if (!n) {
    + memleak_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;
    +}
    +
    +static void *memleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
    +{
    + struct list_head *n;
    + struct memleak_object *next = NULL;
    + unsigned long flags;
    +
    + ++(*pos);
    + if (reported_leaks >= REPORTS_NR)
    + goto out;
    +
    + spin_lock_irqsave(&object_list_lock, flags);
    + n = ((struct memleak_object *)v)->object_list.next;
    + if (n != &object_list) {
    + next = list_entry(n, struct memleak_object, object_list);
    + get_object(next);
    + }
    + spin_unlock_irqrestore(&object_list_lock, flags);
    +
    + out:
    + put_object(v);
    + return next;
    +}
    +
    +static void memleak_seq_stop(struct seq_file *seq, void *v)
    +{
    + if (v)
    + put_object(v);
    +}
    +
    +static int memleak_seq_show(struct seq_file *seq, void *v)
    +{
    + struct memleak_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 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)
    +{
    + int ret = mutex_lock_interruptible(&scan_mutex);
    + if (ret < 0)
    + return ret;
    + ret = seq_open(file, &memleak_seq_ops);
    + if (ret < 0)
    + mutex_unlock(&scan_mutex);
    + return ret;
    +}
    +
    +static int memleak_seq_release(struct inode *inode, struct file *file)
    +{
    + int ret = seq_release(inode, file);
    + mutex_unlock(&scan_mutex);
    + return ret;
    +}
    +
    +static struct file_operations memleak_fops = {
    + .owner = THIS_MODULE,
    + .open = memleak_seq_open,
    + .read = seq_read,
    + .llseek = seq_lseek,
    + .release = memleak_seq_release,
    +};
    +
    +static int memleak_scan_thread(void *arg)
    +{
    + /* sleep before the first scan */
    + ssleep(SECS_FIRST_SCAN);
    +
    + while (!kthread_should_stop()) {
    + struct memleak_object *object;
    +
    + mutex_lock(&scan_mutex);
    +
    + memleak_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++;
    + }
    + spin_unlock_irqrestore(&object->lock, flags);
    + }
    + rcu_read_unlock();
    +
    + mutex_unlock(&scan_mutex);
    + ssleep(SECS_SCAN_PERIOD);
    + }
    +
    + return 0;
    +}
    +
    +/*
    + * Kmemleak initialization.
    + */
    +void __init memleak_init(void)
    +{
    + int i;
    +
    + jiffies_scan_yield = msecs_to_jiffies(MSECS_SCAN_YIELD);
    + jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
    + object_cache = kmem_cache_create("kmemleak_object",
    + sizeof(struct memleak_object),
    + 0, SLAB_NOLEAKTRACE, NULL);
    + scan_area_cache = kmem_cache_create("kmemleak_scan_area",
    + sizeof(struct memleak_scan_area),
    + 0, SLAB_NOLEAKTRACE, NULL);
    + INIT_PRIO_TREE_ROOT(&object_tree_root);
    +
    + /*
    + * This is the point where tracking allocations is safe.
    + * Scanning is only available later.
    + */
    + atomic_set(&memleak_enabled, 1);
    +
    + /* execute the early logged operations */
    + for (i = 0; i < crt_early_log; i++) {
    + struct early_log *log = &early_log[i];
    +
    + switch (log->op_type) {
    + case MEMLEAK_ALLOC:
    + memleak_alloc(log->ptr, log->size, log->ref_count);
    + break;
    + case MEMLEAK_FREE:
    + memleak_free(log->ptr);
    + break;
    + case MEMLEAK_NOT_LEAK:
    + memleak_not_leak(log->ptr);
    + break;
    + case MEMLEAK_IGNORE:
    + memleak_ignore(log->ptr);
    + break;
    + case MEMLEAK_SCAN_AREA:
    + memleak_scan_area(log->ptr, log->offset, log->length);
    + break;
    + default:
    + BUG();
    + }
    + }
    +}
    +
    +/*
    + * Late initialization function.
    + */
    +static int __init memleak_late_init(void)
    +{
    + struct dentry *dentry;
    +
    + dentry = debugfs_create_file("memleak", S_IRUGO, NULL, NULL,
    + &memleak_fops);
    + if (!dentry)
    + return -ENOMEM;
    +
    + scan_thread = kthread_run(memleak_scan_thread, NULL, "kmemleak");
    + if (IS_ERR(scan_thread))
    + pr_warning("kmemleak: Failed to initialise the scan thread\n");
    +
    + pr_info("Kernel memory leak detector initialized\n");
    +
    + return 0;
    +}
    +late_initcall(memleak_late_init);


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      Last update: 2008-11-29 11:47    [W:0.083 / U:0.988 seconds]
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