[PATCH v2 3/3] kasan: update documentation for generic kasan

[Walter Wu]

Generic KASAN will support to record first and last call_rcu() call
stack and print them in KASAN report. so we update documentation.

Signed-off-by: Walter Wu <walter-zh.wu@xxxxxxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
---
 Documentation/dev-tools/kasan.rst | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst
index c652d740735d..d4efcfde9fff 100644
--- a/Documentation/dev-tools/kasan.rst
+++ b/Documentation/dev-tools/kasan.rst
@@ -193,6 +193,12 @@ function calls GCC directly inserts the code to check the shadow memory.
 This option significantly enlarges kernel but it gives x1.1-x2 performance
 boost over outline instrumented kernel.
 
+Currently generic KASAN can print call_rcu() call stack in KASAN report, it
+can't increase the cost of memory consumption, but it has one limitations.
+It can't get both call_rcu() call stack and free stack, so that it can't
+print free stack for allocation objects in KASAN report. This feature is
+only suitable for generic KASAN.
+
 Software tag-based KASAN
 ~~~~~~~~~~~~~~~~~~~~~~~~
 
-- 
2.18.0