userfaultfd.2: BUGS: document spurious UFFD_EVENT_FORK

Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

diff --git a/man2/userfaultfd.2 b/man2/userfaultfd.2
index 1c9e64baf32e29f960446ffef411917240ad7e11..08c41e160c4545e54768c8bd313ae668ccc27722 100644 (file)
--- a/man2/userfaultfd.2
+++ b/man2/userfaultfd.2
@@ -465,6 +465,16 @@ for checkpoint/restore mechanisms,
 as well as post-copy migration to allow (nearly) uninterrupted execution
 when transferring virtual machines and Linux containers
 from one host to another.
+.SH BUGS
+If the
+.B UFFD_FEATURE_EVENT_FORK
+is enabled and a system call from the
+.BR fork (2)
+family is interrupted by a signal or failed,q a stale userfaultfd descriptor
+might be created.
+In this case a spurious
+.B UFFD_EVENT_FORK
+will be delivered to the userfaultfd monitor.
 .SH EXAMPLE
 The program below demonstrates the use of the userfaultfd mechanism.
 The program creates two threads, one of which acts as the