[PATCH 5/5] usefaultfd.2: add brief description of "non-cooperative" mode

[Mike Rapoport]

Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
---
 man2/userfaultfd.2 | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/man2/userfaultfd.2 b/man2/userfaultfd.2
index dc37319..291dd10 100644
--- a/man2/userfaultfd.2
+++ b/man2/userfaultfd.2
@@ -89,6 +89,20 @@ them using the operations described in
 .BR ioctl_userfaultfd (2).
 When servicing the page fault events,
 the fault-handling thread can trigger a wake-up for the sleeping thread.
+
+It is possible for the faulting threads and the fault-handling threads
+to run in the context of different processes.
+In this case, these threads may belong to different programs,
+and the program that executes the faulting threads
+will not necessarily cooperate with the program that handles the page faults.
+In such non-cooperative mode,
+the process that monitors userfaultfd and handles page faults,
+needs to be aware of the changes in the virtual memory layout
+of the faulting process to avoid memory corruption.
+.\" FIXME elaborate about non-cooperating mode, describe its limitations
+.\" for kerneles before 4.11, features added in 4.11
+.\" and limitations remaining in 4.11
+.\" Maybe it's worth adding a dedicated sub-section...
 .\"
 .SS Userfaultfd operation
 After the userfaultfd object is created with
-- 
1.9.1