1 files changed, 71 insertions, 126 deletions

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index c96f2c8700aa..e766e1da09d2 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -48,10 +48,10 @@
  *   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
+ *   added to the gray_list and therefore cannot be freed. This mutex also
+ *   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
@@ -105,7 +105,6 @@
 #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 */
 
@@ -186,19 +185,16 @@ static atomic_t kmemleak_error = ATOMIC_INIT(0);
 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;
+/* used to avoid reporting of recently allocated objects */
 static unsigned long jiffies_min_age;
+static unsigned long jiffies_last_scan;
 /* 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 int kmemleak_stack_scan = 1;
+/* protects the memory scanning, parameters and debug/kmemleak file access */
 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;
@@ -235,7 +231,7 @@ struct early_log {
 };
 
 /* early logging buffer and current position */
-static struct early_log early_log[200];
+static struct early_log early_log[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE];
 static int crt_early_log;
 
 static void kmemleak_disable(void);
@@ -279,15 +275,6 @@ static int color_gray(const struct kmemleak_object *object)
 }
 
 /*
- * 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.
@@ -295,42 +282,28 @@ static int referenced_object(struct kmemleak_object *object)
 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);
+                time_before_eq(object->jiffies + jiffies_min_age,
+                               jiffies_last_scan);
 }
 
 /*
- * 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.
+ * Printing of the unreferenced objects information to the seq file. The
+ * print_unreferenced function 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("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, "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");
+        seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n",
+                   object->pointer, object->size);
+        seq_printf(seq, "  comm \"%s\", pid %d, jiffies %lu\n",
+                   object->comm, object->pid, object->jiffies);
+        seq_printf(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);
+                seq_printf(seq, "    [<%p>] %pS\n", ptr, ptr);
         }
 }
 
@@ -554,8 +527,10 @@ static void delete_object(unsigned long ptr)
         write_lock_irqsave(&kmemleak_lock, flags);
         object = lookup_object(ptr, 0);
         if (!object) {
+#ifdef DEBUG
                 kmemleak_warn("Freeing unknown object at 0x%08lx\n",
                               ptr);
+#endif
                 write_unlock_irqrestore(&kmemleak_lock, flags);
                 return;
         }
@@ -571,8 +546,6 @@ static void delete_object(unsigned long ptr)
          * 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);
@@ -696,7 +669,8 @@ static void log_early(int op_type, const void *ptr, size_t size,
         struct early_log *log;
 
         if (crt_early_log >= ARRAY_SIZE(early_log)) {
-                kmemleak_stop("Early log buffer exceeded\n");
+                pr_warning("Early log buffer exceeded\n");
+                kmemleak_disable();
                 return;
         }
 
@@ -808,21 +782,6 @@ void kmemleak_no_scan(const void *ptr)
 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.
  */
@@ -862,15 +821,6 @@ static void scan_block(void *_start, void *_end,
                 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;
@@ -952,6 +902,9 @@ static void kmemleak_scan(void)
         struct kmemleak_object *object, *tmp;
         struct task_struct *task;
         int i;
+        int new_leaks = 0;
+
+        jiffies_last_scan = jiffies;
 
         /* prepare the kmemleak_object's */
         rcu_read_lock();
@@ -1033,7 +986,7 @@ static void kmemleak_scan(void)
          */
         object = list_entry(gray_list.next, typeof(*object), gray_list);
         while (&object->gray_list != &gray_list) {
-                scan_yield();
+                cond_resched();
 
                 /* may add new objects to the list */
                 if (!scan_should_stop())
@@ -1049,6 +1002,32 @@ static void kmemleak_scan(void)
                 object = tmp;
         }
         WARN_ON(!list_empty(&gray_list));
+
+        /*
+         * If scanning was stopped do not report any new unreferenced objects.
+         */
+        if (scan_should_stop())
+                return;
+
+        /*
+         * Scanning result reporting.
+         */
+        rcu_read_lock();
+        list_for_each_entry_rcu(object, &object_list, object_list) {
+                spin_lock_irqsave(&object->lock, flags);
+                if (unreferenced_object(object) &&
+                    !(object->flags & OBJECT_REPORTED)) {
+                        object->flags |= OBJECT_REPORTED;
+                        new_leaks++;
+                }
+                spin_unlock_irqrestore(&object->lock, flags);
+        }
+        rcu_read_unlock();
+
+        if (new_leaks)
+                pr_info("%d new suspected memory leaks (see "
+                        "/sys/kernel/debug/kmemleak)\n", new_leaks);
+
 }
 
 /*
@@ -1070,36 +1049,12 @@ static int kmemleak_scan_thread(void *arg)
         }
 
         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);
@@ -1112,7 +1067,7 @@ static int kmemleak_scan_thread(void *arg)
 
 /*
  * Start the automatic memory scanning thread. This function must be called
- * with the kmemleak_mutex held.
+ * with the scan_mutex held.
  */
 void start_scan_thread(void)
 {
@@ -1127,7 +1082,7 @@ void start_scan_thread(void)
 
 /*
  * Stop the automatic memory scanning thread. This function must be called
- * with the kmemleak_mutex held.
+ * with the scan_mutex held.
  */
 void stop_scan_thread(void)
 {
@@ -1147,10 +1102,8 @@ static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
         struct kmemleak_object *object;
         loff_t n = *pos;
 
-        if (!n) {
-                kmemleak_scan();
+        if (!n)
                 reported_leaks = 0;
-        }
         if (reported_leaks >= REPORTS_NR)
                 return NULL;
 
@@ -1211,11 +1164,10 @@ static int kmemleak_seq_show(struct seq_file *seq, void *v)
         unsigned long flags;
 
         spin_lock_irqsave(&object->lock, flags);
-        if (!unreferenced_object(object))
-                goto out;
-        print_unreferenced(seq, object);
-        reported_leaks++;
-out:
+        if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object)) {
+                print_unreferenced(seq, object);
+                reported_leaks++;
+        }
         spin_unlock_irqrestore(&object->lock, flags);
         return 0;
 }
@@ -1234,13 +1186,10 @@ static int kmemleak_open(struct inode *inode, struct file *file)
         if (!atomic_read(&kmemleak_enabled))
                 return -EBUSY;
 
-        ret = mutex_lock_interruptible(&kmemleak_mutex);
+        ret = mutex_lock_interruptible(&scan_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;
@@ -1249,8 +1198,6 @@ static int kmemleak_open(struct inode *inode, struct file *file)
 
 scan_unlock:
         mutex_unlock(&scan_mutex);
-kmemleak_unlock:
-        mutex_unlock(&kmemleak_mutex);
 out:
         return ret;
 }
@@ -1259,11 +1206,9 @@ static int kmemleak_release(struct inode *inode, struct file *file)
 {
         int ret = 0;
 
-        if (file->f_mode & FMODE_READ) {
+        if (file->f_mode & FMODE_READ)
                 seq_release(inode, file);
-                mutex_unlock(&scan_mutex);
-        }
-        mutex_unlock(&kmemleak_mutex);
+        mutex_unlock(&scan_mutex);
 
         return ret;
 }
@@ -1278,6 +1223,7 @@ static int kmemleak_release(struct inode *inode, struct file *file)
  *   scan=off   - stop the automatic memory scanning thread
  *   scan=...   - set the automatic memory scanning period in seconds (0 to
  *                disable it)
+ *   scan       - trigger a memory scan
  */
 static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
                               size_t size, loff_t *ppos)
@@ -1315,7 +1261,9 @@ static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
                         jiffies_scan_wait = msecs_to_jiffies(secs * 1000);
                         start_scan_thread();
                 }
-        } else
+        } else if (strncmp(buf, "scan", 4) == 0)
+                kmemleak_scan();
+        else
                 return -EINVAL;
 
         /* ignore the rest of the buffer, only one command at a time */
@@ -1340,11 +1288,9 @@ static int kmemleak_cleanup_thread(void *arg)
 {
         struct kmemleak_object *object;
 
-        mutex_lock(&kmemleak_mutex);
+        mutex_lock(&scan_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);
@@ -1411,7 +1357,6 @@ 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);
 
@@ -1486,9 +1431,9 @@ static int __init kmemleak_late_init(void)
                                      &kmemleak_fops);
         if (!dentry)
                 pr_warning("Failed to create the debugfs kmemleak file\n");
-        mutex_lock(&kmemleak_mutex);
+        mutex_lock(&scan_mutex);
         start_scan_thread();
-        mutex_unlock(&kmemleak_mutex);
+        mutex_unlock(&scan_mutex);
 
         pr_info("Kernel memory leak detector initialized\n");