Fix CG with multiple domains

The global state can only be accessed on master rank, so we should set
the flags there and then permit the DD code to propagate the setup of
the cg_p vector.

Fixes #2554

Change-Id: If294bf000eb0266125ecc6c6bf937aac0390e2b8

diff --git a/docs/release-notes/2018/2018.3.rst b/docs/release-notes/2018/2018.3.rst
index 4f13f68ea82424b1c23407f9dbce86b9143d77e9..251ca127fc335aae3954c91a5b271cdc4807cca3 100644 (file)
--- a/docs/release-notes/2018/2018.3.rst
+++ b/docs/release-notes/2018/2018.3.rst
@@ -8,6 +8,9 @@ earlier, which you can find described in the :ref:`release-notes`.
 
 Fixes where mdrun could behave incorrectly
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+Multi-domain Conjugate Gradient minimimization no longer segfaults.
+
+:issue:`2554`
 
 Fixes for ``gmx`` tools
 ^^^^^^^^^^^^^^^^^^^^^^^

diff --git a/src/gromacs/mdlib/minimize.cpp b/src/gromacs/mdlib/minimize.cpp
index 961d95e27f53751a3167cdf83fe81788a0961182..cbf10a7c7fe9ba6addd0440c3495a6b885419f04 100644 (file)
--- a/src/gromacs/mdlib/minimize.cpp
+++ b/src/gromacs/mdlib/minimize.cpp
@@ -1043,8 +1043,11 @@ double do_cg(FILE *fplog, t_commrec *cr, const gmx::MDLogger gmx_unused &mdlog,
 
     step = 0;
 
-    // Ensure the extra per-atom state array gets allocated
-    state_global->flags |= (1<<estCGP);
+    if (MASTER(cr))
+    {
+        // Ensure the extra per-atom state array gets allocated
+        state_global->flags |= (1<<estCGP);
+    }
 
     /* Create 4 states on the stack and extract pointers that we will swap */
     em_state_t  s0 {}, s1 {}, s2 {}, s3 {};