[PATCH v2 2/3] doc/vm: add information about page_table_check warn_on behavior

[Pasha Tatashin <pasha.tatashin@soleen.com>]

The default behavior of page table check was changed from panicking
kernel to printing a warning.

Add a note how to still panic the kernel when error is detected.

Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
---
 Documentation/mm/page_table_check.rst | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/Documentation/mm/page_table_check.rst b/Documentation/mm/page_table_check.rst
index c12838ce6b8d..f534c80ee9c9 100644
--- a/Documentation/mm/page_table_check.rst
+++ b/Documentation/mm/page_table_check.rst
@@ -14,13 +14,14 @@ Page table check performs extra verifications at the time when new pages become
 accessible from the userspace by getting their page table entries (PTEs PMDs
 etc.) added into the table.
 
-In case of detected corruption, the kernel is crashed. There is a small
+In case of detected corruption, a warning is printed. There is a small
 performance and memory overhead associated with the page table check. Therefore,
 it is disabled by default, but can be optionally enabled on systems where the
 extra hardening outweighs the performance costs. Also, because page table check
 is synchronous, it can help with debugging double map memory corruption issues,
 by crashing kernel at the time wrong mapping occurs instead of later which is
-often the case with memory corruptions bugs.
+often the case with memory corruptions bugs. In order to crash kernel sysctl
+panic_on_warn should be set to 1.
 
 Double mapping detection logic
 ==============================
-- 
2.41.0.487.g6d72f3e995-goog