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>

diff --git a/Documentation/kmemleak.txt b/Documentation/kmemleak.txt
index 89068030b01bbdb34392df6bf4fd8782d928ac57..c223785339b5a3dd1c53c2e32a9f0585c05a234e 100644 (file)
--- a/Documentation/kmemleak.txt
+++ b/Documentation/kmemleak.txt
@@ -42,6 +42,7 @@ Memory scanning parameters can be modified at run-time by writing to the
   scan=<secs>  - set the automatic memory scanning period in seconds
                  (default 600, 0 to stop the automatic scanning)
   scan         - trigger a memory scan
+  dump=<addr>  - dump information about the object found at <addr>
 
 Kmemleak can also be disabled at boot-time by passing "kmemleak=off" on
 the kernel command line.

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 6debe0d80e641bfe31e6c32243a154f920c55280..c977f7a2f0e47fa3fbbc06adf452e7058d58f3f5 100644 (file)
--- 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;