Fix a bug.

diff --git a/src/backend/utils/mmgr/sb_alloc.c b/src/backend/utils/mmgr/sb_alloc.c
index 7b983a4d665680550d7c2cef82631080ca489b1a..d8923fdca8b955e58153ac4f563de5f3896701f0 100644 (file)
--- a/src/backend/utils/mmgr/sb_alloc.c
+++ b/src/backend/utils/mmgr/sb_alloc.c
@@ -341,9 +341,9 @@ sb_free(void *ptr)
                relptr_store(base, span->prevspan, (sb_span *) NULL);
                new_nextspan = relptr_access(base,
                                                                         heap->spans[SB_FULLNESS_CLASSES - 2]);
-               relptr_store(base, new_nextspan->prevspan, span);
-               relptr_copy(heap->spans[SB_FULLNESS_CLASSES - 2],
-                                       new_nextspan->prevspan);
+               if (new_nextspan != NULL)
+                       relptr_store(base, new_nextspan->prevspan, span);
+               relptr_store(base, heap->spans[SB_FULLNESS_CLASSES - 2], span);
        }
        else if (span->nallocatable == span->nmax)
        {