From 0793a5859315d6682a058414f2627441c52f24bc Mon Sep 17 00:00:00 2001
From: "Nicholas S. Park" <nspark.work@gmail.com>
Date: Wed, 5 Feb 2020 11:17:01 -0600
Subject: [PATCH] section/collectives: Clarify UB for data races with
 collectives

Closes #74
---
 content/collective_intro.tex | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/content/collective_intro.tex b/content/collective_intro.tex
index 5f7165206..e4495c684 100644
--- a/content/collective_intro.tex
+++ b/content/collective_intro.tex
@@ -18,6 +18,12 @@
   required, the default context.
 \end{enumerate}
 
+Concurrent accesses to symmetric memory by an \openshmem collective
+routine and any other means of access---where at least one updates the
+symmetric memory---results in undefined behavior.
+Since \acp{PE} can enter and exit collectives at different times,
+accessing such memory remotely may require additional synchronization.
+
 \subsubsection*{Team-based collectives}
 
 The team-based collective routines are performed with respect to a valid