kmemleak: Allow rescheduling during an object scanning

[net-next-2.6.git] / mm / kmemleak.c

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 5aabd41ffb8fafbea9fd3a507d9ac5ef6a679e25..6debe0d80e641bfe31e6c32243a154f920c55280 100644 (file)
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -107,6 +107,7 @@
 #define SECS_FIRST_SCAN                60      /* delay before the first scan */
 #define SECS_SCAN_WAIT         600     /* subsequent auto scanning delay */
 #define GRAY_LIST_PASSES       25      /* maximum number of gray list scans */
+#define MAX_SCAN_SIZE          4096    /* maximum size of a scanned block */
 
 #define BYTES_PER_POINTER      sizeof(void *)
 
@@ -642,6 +643,7 @@ static void make_black_object(unsigned long ptr)
 
        spin_lock_irqsave(&object->lock, flags);
        object->min_count = -1;
+       object->flags |= OBJECT_NO_SCAN;
        spin_unlock_irqrestore(&object->lock, flags);
        put_object(object);
 }
@@ -949,10 +951,21 @@ static void scan_object(struct kmemleak_object *object)
        if (!(object->flags & OBJECT_ALLOCATED))
                /* already freed object */
                goto out;
-       if (hlist_empty(&object->area_list))
-               scan_block((void *)object->pointer,
-                          (void *)(object->pointer + object->size), object, 0);
-       else
+       if (hlist_empty(&object->area_list)) {
+               void *start = (void *)object->pointer;
+               void *end = (void *)(object->pointer + object->size);
+
+               while (start < end && (object->flags & OBJECT_ALLOCATED) &&
+                      !(object->flags & OBJECT_NO_SCAN)) {
+                       scan_block(start, min(start + MAX_SCAN_SIZE, end),
+                                  object, 0);
+                       start += MAX_SCAN_SIZE;
+
+                       spin_unlock_irqrestore(&object->lock, flags);
+                       cond_resched();
+                       spin_lock_irqsave(&object->lock, flags);
+               }
+       } else
                hlist_for_each_entry(area, elem, &object->area_list, node)
                        scan_block((void *)(object->pointer + area->offset),
                                   (void *)(object->pointer + area->offset
@@ -1217,7 +1230,6 @@ static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
        }
        object = NULL;
 out:
-       rcu_read_unlock();
        return object;
 }
 
@@ -1233,13 +1245,11 @@ static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 
        ++(*pos);
 
-       rcu_read_lock();
        list_for_each_continue_rcu(n, &object_list) {
                next_obj = list_entry(n, struct kmemleak_object, object_list);
                if (get_object(next_obj))
                        break;
        }
-       rcu_read_unlock();
 
        put_object(prev_obj);
        return next_obj;
@@ -1255,6 +1265,7 @@ static void kmemleak_seq_stop(struct seq_file *seq, void *v)
                 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
                 * waiting was interrupted, so only release it if !IS_ERR.
                 */
+               rcu_read_unlock();
                mutex_unlock(&scan_mutex);
                if (v)
                        put_object(v);