6912018: CMS: guarantee(head() != 0,"The head of the list cannot be NULL")
Summary: Block too small to split was not correctly putback to free lists.
Reviewed-by: ysr
--- a/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp Mon Jan 04 14:51:26 2010 -0800
+++ b/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp Thu Jan 07 08:14:45 2010 -0800
@@ -3075,7 +3075,18 @@
if (rem > 0 && rem < MinChunkSize) {
n--; rem += word_sz;
}
- assert((ssize_t)n >= 1, "Control point invariant");
+ // Note that at this point we may have n == 0.
+ assert((ssize_t)n >= 0, "Control point invariant");
+
+ // If n is 0, the chunk fc that was found is not large
+ // enough to leave a viable remainder. We are unable to
+ // allocate even one block. Return fc to the
+ // dictionary and return, leaving "fl" empty.
+ if (n == 0) {
+ returnChunkToDictionary(fc);
+ return;
+ }
+
// First return the remainder, if any.
// Note that we hold the lock until we decide if we're going to give
// back the remainder to the dictionary, since a concurrent allocation