kmemleak: Dump object information on request

By writing dump=<addr> to the kmemleak file, kmemleak will look up an
object with that address and dump the information it has about it to
syslog. This is useful in debugging memory leaks.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 6debe0d80e64..c977f7a2f0e4 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -331,6 +331,7 @@ static void dump_object_info(struct kmemleak_object *object)
                   object->comm, object->pid, object->jiffies);
         pr_notice("  min_count = %d\n", object->min_count);
         pr_notice("  count = %d\n", object->count);
+        pr_notice("  flags = 0x%lx\n", object->flags);
         pr_notice("  backtrace:\n");
         print_stack_trace(&trace, 4);
 }
@@ -1307,6 +1308,27 @@ static int kmemleak_release(struct inode *inode, struct file *file)
         return seq_release(inode, file);
 }
 
+static int dump_str_object_info(const char *str)
+{
+        unsigned long flags;
+        struct kmemleak_object *object;
+        unsigned long addr;
+
+        addr= simple_strtoul(str, NULL, 0);
+        object = find_and_get_object(addr, 0);
+        if (!object) {
+                pr_info("Unknown object at 0x%08lx\n", addr);
+                return -EINVAL;
+        }
+
+        spin_lock_irqsave(&object->lock, flags);
+        dump_object_info(object);
+        spin_unlock_irqrestore(&object->lock, flags);
+
+        put_object(object);
+        return 0;
+}
+
 /*
  * File write operation to configure kmemleak at run-time. The following
  * commands can be written to the /sys/kernel/debug/kmemleak file:
@@ -1318,6 +1340,7 @@ static int kmemleak_release(struct inode *inode, struct file *file)
  *   scan=...   - set the automatic memory scanning period in seconds (0 to
  *                disable it)
  *   scan       - trigger a memory scan
+ *   dump=...   - dump information about the object found at the given address
  */
 static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
                               size_t size, loff_t *ppos)
@@ -1358,6 +1381,8 @@ static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
                 }
         } else if (strncmp(buf, "scan", 4) == 0)
                 kmemleak_scan();
+        else if (strncmp(buf, "dump=", 5) == 0)
+                ret = dump_str_object_info(buf + 5);
         else
                 ret = -EINVAL;