From 0a7eb0aa0bf7e7464e68ab9b6f4176771dcc3590 Mon Sep 17 00:00:00 2001
From: Ben Gamari <ben@smart-cactus.org>
Date: Mon, 5 Dec 2022 18:59:31 -0500
Subject: nonmoving: Be more paranoid in segment tracking

Previously we left various segment link pointers dangling. None of this
wrong per se, but it did make it harder than necessary to debug.
---
 rts/sm/NonMoving.c     | 3 +++
 rts/sm/NonMovingMark.c | 2 ++
 rts/sm/Storage.c       | 3 ++-
 3 files changed, 7 insertions(+), 1 deletion(-)

(limited to 'rts')

diff --git a/rts/sm/NonMoving.c b/rts/sm/NonMoving.c
index bbb499f4da..251151f287 100644
--- a/rts/sm/NonMoving.c
+++ b/rts/sm/NonMoving.c
@@ -850,6 +850,7 @@ static void nonmovingPrepareMark(void)
 
         // Save the filled segments for later processing during the concurrent
         // mark phase.
+        ASSERT(alloca->saved_filled == NULL);
         alloca->saved_filled = alloca->filled;
         alloca->filled = NULL;
 
@@ -925,6 +926,7 @@ void nonmovingCollect(StgWeak **dead_weaks, StgTSO **resurrected_threads)
     ASSERT(n_nonmoving_marked_compact_blocks == 0);
 
     MarkQueue *mark_queue = stgMallocBytes(sizeof(MarkQueue), "mark queue");
+    mark_queue->blocks = NULL;
     initMarkQueue(mark_queue);
     current_mark_queue = mark_queue;
 
@@ -1088,6 +1090,7 @@ static void nonmovingMark_(MarkQueue *mark_queue, StgWeak **dead_weaks, StgTSO *
             seg->link = nonmovingHeap.sweep_list;
             nonmovingHeap.sweep_list = filled;
         }
+        nonmovingHeap.allocators[alloca_idx]->saved_filled = NULL;
     }
 
     // Mark Weak#s
diff --git a/rts/sm/NonMovingMark.c b/rts/sm/NonMovingMark.c
index 1b1e1c7b79..02cecd154f 100644
--- a/rts/sm/NonMovingMark.c
+++ b/rts/sm/NonMovingMark.c
@@ -271,6 +271,7 @@ static void nonmovingAddUpdRemSetBlocks_(MarkQueue *rset)
     bdescr *end = start;
     while (end->link != NULL)
         end = end->link;
+    rset->blocks = NULL;
 
     // add the blocks to the global remembered set
     ACQUIRE_LOCK(&upd_rem_set_lock);
@@ -930,6 +931,7 @@ static MarkQueueEnt markQueuePop (MarkQueue *q)
 static void init_mark_queue_ (MarkQueue *queue)
 {
     bdescr *bd = allocGroup(MARK_QUEUE_BLOCKS);
+    ASSERT(queue->blocks == NULL);
     queue->blocks = bd;
     queue->top = (MarkQueueBlock *) bd->start;
     queue->top->head = 0;
diff --git a/rts/sm/Storage.c b/rts/sm/Storage.c
index d5b78ba12d..0309d3a565 100644
--- a/rts/sm/Storage.c
+++ b/rts/sm/Storage.c
@@ -324,7 +324,8 @@ void storageAddCapabilities (uint32_t from, uint32_t to)
     // Initialize NonmovingAllocators and UpdRemSets
     if (RtsFlags.GcFlags.useNonmoving) {
         nonmovingAddCapabilities(to);
-        for (i = from; i < to; ++i) {
+        for (i = from; i < to; i++) {
+            getCapability(i)->upd_rem_set.queue.blocks = NULL;
             nonmovingInitUpdRemSet(&getCapability(i)->upd_rem_set);
         }
     }
-- 
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