Allow running memInventory when the concurrent nonmoving gc is enabled

If the nonmoving gc is enabled and we are using a threaded RTS,
we now try to grab the collector mutex to avoid memInventory and
the collection racing.

Before memInventory was disabled.

2 files changed, 14 insertions, 5 deletions

diff --git a/rts/sm/NonMoving.h b/rts/sm/NonMoving.h
index 6eabcb8493..17c0a3bec0 100644
--- a/rts/sm/NonMoving.h
+++ b/rts/sm/NonMoving.h
@@ -104,6 +104,7 @@ extern memcount nonmoving_live_words;
 
 #if defined(THREADED_RTS)
 extern bool concurrent_coll_running;
+extern Mutex nonmoving_collection_mutex;
 #endif
 
 void nonmovingInit(void);
diff --git a/rts/sm/Sanity.c b/rts/sm/Sanity.c
index 9c2ccc2c41..ba381bfc2c 100644
--- a/rts/sm/Sanity.c
+++ b/rts/sm/Sanity.c
@@ -1190,11 +1190,12 @@ memInventory (bool show)
   bool leak;
 
 #if defined(THREADED_RTS)
-  // Can't easily do a memory inventory: We might race with the nonmoving
-  // collector. In principle we could try to take nonmoving_collection_mutex
-  // and do an inventory if we have it but we don't currently implement this.
-  if (RtsFlags.GcFlags.useNonmoving)
-    return;
+  // We need to be careful not to race with the nonmoving collector.
+  // If a nonmoving collection is on-going we simply abort the inventory.
+  if (RtsFlags.GcFlags.useNonmoving){
+    if(TRY_ACQUIRE_LOCK(&nonmoving_collection_mutex))
+      return;
+  }
 #endif
 
   // count the blocks we current have
@@ -1298,6 +1299,13 @@ memInventory (bool show)
   }
   ASSERT(n_alloc_blocks == live_blocks);
   ASSERT(!leak);
+
+#if defined(THREADED_RTS)
+  if (RtsFlags.GcFlags.useNonmoving){
+    RELEASE_LOCK(&nonmoving_collection_mutex);
+  }
+#endif
+
 }