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Subject[PATCH 5/5] usefaultfd.2: add brief description of "non-cooperative" mode
Date
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
---
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
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