for (int level = start_level; level >= 0; --level) {
TRACE("s3", "find_preds: level %llu", level, 0);
item = pred->next[level];
if (EXPECT_FALSE(IS_TAGGED(item))) {
TRACE("s3", "find_preds: pred %p is marked for removal (item %p); retry", pred, item);
for (int level = start_level; level >= 0; --level) {
TRACE("s3", "find_preds: level %llu", level, 0);
item = pred->next[level];
if (EXPECT_FALSE(IS_TAGGED(item))) {
TRACE("s3", "find_preds: pred %p is marked for removal (item %p); retry", pred, item);