[tip:core/debugobjects] debugobjects: Make stack check warning more informative

["tip-bot for Joel Fernandes (Google)" <tipbot@zytor.com>]

Commit-ID:  fc91a3c4c27acdca0bc13af6fbb68c35cfd519f2
Gitweb:     https://git.kernel.org/tip/fc91a3c4c27acdca0bc13af6fbb68c35cfd519f2
Author:     Joel Fernandes (Google) <joel@joelfernandes.org>
AuthorDate: Mon, 23 Jul 2018 14:25:31 -0700
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Mon, 30 Jul 2018 21:36:37 +0200

debugobjects: Make stack check warning more informative

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

---
 lib/debugobjects.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/lib/debugobjects.c b/lib/debugobjects.c
index 994be4805cec..24c1df0d7466 100644
--- a/lib/debugobjects.c
+++ b/lib/debugobjects.c
@@ -360,9 +360,12 @@ 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);
 }