diff --git a/deps/oblib/src/lib/alloc/alloc_struct.h b/deps/oblib/src/lib/alloc/alloc_struct.h
index 9a940dfbc5..8a6c102e17 100644
--- a/deps/oblib/src/lib/alloc/alloc_struct.h
+++ b/deps/oblib/src/lib/alloc/alloc_struct.h
@@ -157,7 +157,7 @@ struct AChunk {
   OB_INLINE char *blk_data(const ABlock *block) const;
   OB_INLINE void mark_unused_blk_offset_bit(int offset);
   OB_INLINE void unmark_unused_blk_offset_bit(int offset);
-
+  OB_INLINE bool is_all_blks_unused();
   union {
     uint32_t MAGIC_CODE_;
     struct {
@@ -361,6 +361,20 @@ void AChunk::unmark_unused_blk_offset_bit(int offset)
   unused_blk_bs_.unset(offset);
 }
 
+bool AChunk::is_all_blks_unused()
+{
+  bool ret = false;
+  if (0 != washed_size_) {
+    auto blk_bs = blk_bs_;
+    blk_bs.combine(unused_blk_bs_,
+          [](int64_t left, int64_t right) { return (left ^ right); });
+    ret = -1 == blk_bs.min_bit_ge(0);
+  } else {
+    ret = -1 == blk_bs_.min_bit_ge(1);
+  }
+  return ret;
+}
+
 ABlock *AChunk::offset2blk(int offset) const
 {
   return (ABlock*)data_ + offset;
diff --git a/deps/oblib/src/lib/alloc/block_set.cpp b/deps/oblib/src/lib/alloc/block_set.cpp
index 6862c0bada..38a623d367 100644
--- a/deps/oblib/src/lib/alloc/block_set.cpp
+++ b/deps/oblib/src/lib/alloc/block_set.cpp
@@ -172,19 +172,9 @@ void BlockSet::free_block(ABlock *const block)
       // head won't been NULL,
       if (head != NULL) {
         head->in_use_ = false;
-        bool all_blocks_unused = false;
         // copy a temp
         chunk->mark_unused_blk_offset_bit(chunk->blk_offset(head));
-        if (0 != chunk->washed_size_) {
-          auto blk_bs = chunk->blk_bs_;
-          blk_bs.combine(chunk->unused_blk_bs_,
-                [](int64_t left, int64_t right) { return (left ^ right); });
-          all_blocks_unused = -1 == blk_bs.min_bit_ge(0);
-        } else {
-          all_blocks_unused = -1 == chunk->blk_bs_.min_bit_ge(1);
-        }
-
-        if (all_blocks_unused) {
+        if (chunk->is_all_blks_unused()) {
           if (0 != chunk->washed_size_) {
             int offset = 0;
             do {
@@ -348,7 +338,7 @@ void BlockSet::free_chunk(AChunk *const chunk)
   abort_unless(NULL != chunk->next_);
   abort_unless(NULL != chunk->prev_);
   abort_unless(NULL != clist_);
-
+  abort_unless(chunk->is_all_blks_unused());
   if (chunk == clist_) {
     clist_ = clist_->next_;
   }