kmemleak: Report previously found leaks even after an error
If an error fatal to kmemleak (like memory allocation failure) happens,
kmemleak disables itself but it also removes the access to any
previously found memory leaks. This patch allows read-only access to the
kmemleak debugfs interface but disables any other action.
Reported-by: Nick Bowler <nbowler@elliptictech.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index e8c905b..b4f4e60 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -1473,9 +1473,6 @@
static int kmemleak_open(struct inode *inode, struct file *file)
{
- if (!atomic_read(&kmemleak_enabled))
- return -EBUSY;
-
return seq_open(file, &kmemleak_seq_ops);
}
@@ -1549,6 +1546,9 @@
int buf_size;
int ret;
+ if (!atomic_read(&kmemleak_enabled))
+ return -EBUSY;
+
buf_size = min(size, (sizeof(buf) - 1));
if (strncpy_from_user(buf, user_buf, buf_size) < 0)
return -EFAULT;
@@ -1608,20 +1608,24 @@
};
/*
- * Perform the freeing of the kmemleak internal objects after waiting for any
- * current memory scan to complete.
+ * Stop the memory scanning thread and free the kmemleak internal objects if
+ * no previous scan thread (otherwise, kmemleak may still have some useful
+ * information on memory leaks).
*/
static void kmemleak_do_cleanup(struct work_struct *work)
{
struct kmemleak_object *object;
+ bool cleanup = scan_thread == NULL;
mutex_lock(&scan_mutex);
stop_scan_thread();
- rcu_read_lock();
- list_for_each_entry_rcu(object, &object_list, object_list)
- delete_object_full(object->pointer);
- rcu_read_unlock();
+ if (cleanup) {
+ rcu_read_lock();
+ list_for_each_entry_rcu(object, &object_list, object_list)
+ delete_object_full(object->pointer);
+ rcu_read_unlock();
+ }
mutex_unlock(&scan_mutex);
}