debugobjects: Make stack check warning more informative

BugLink: https://bugs.launchpad.net/bugs/1835972
commit fc91a3c4c27acdca0bc13af6fbb68c35cfd519f2 upstream.

While debugging an issue debugobject tracking warned about an annotation
issue of an object on stack. It turned out that the issue was due to the
object in concern being on a different stack which was due to another
issue.

Thomas suggested to print the pointers and the location of the stack for
the currently running task. This helped to figure out that the object was
on the wrong stack.

As this is general useful information for debugging similar issues, make
the error message more informative by printing the pointers.

[ tglx: Massaged changelog ]

Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Waiman Long <longman@redhat.com>
Acked-by: Yang Shi <yang.shi@linux.alibaba.com>
Cc: kernel-team@android.com
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: astrachan@google.com
Link: https://lkml.kernel.org/r/20180723212531.202328-1-joel@joelfernandes.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

diff --git a/lib/debugobjects.c b/lib/debugobjects.c
index 2f5349c6e81ae01b0cca972570f3b7920aca246e..99308479b1c80276ee814217fa4f7136b1b86906 100644 (file)
--- a/lib/debugobjects.c
+++ b/lib/debugobjects.c
@@ -322,9 +322,12 @@ static void debug_object_is_on_stack(void *addr, int onstack)
 
        limit++;
        if (is_on_stack)
-               pr_warn("object is on stack, but not annotated\n");
+               pr_warn("object %p is on stack %p, but NOT annotated.\n", addr,
+                        task_stack_page(current));
        else
-               pr_warn("object is not on stack, but annotated\n");
+               pr_warn("object %p is NOT on stack %p, but annotated.\n", addr,
+                        task_stack_page(current));
+
        WARN_ON(1);
 }