百思不得其解关于HashMap源码

为了简化问题我们不考虑，位桶内是红黑树的情况。假设位桶内是链表，源码中通过p = tab[i = (n - 1) & hash]取出来了当前的Node，那么该链表上所有的Node的节点的hash属性就是与key的hash相同的，遍历的时候为什么还需要再次判断一下key的hash是否等于node内存的key的hash？
源码：
p.hash == hash &&((k = p.key) == key || (key != null && key.equals(k)))

代码中p.hash == hash 的意义是什么？

已解决：之前陷入了误区，一个桶内的Node hash并不一定是相同的，桶的位置是由取模运算确定的。

附上HashMap源码 jdk8

final V putVal(int hash, K key, V value, boolean onlyIfAbsent,
                   boolean evict) {
        Node<K,V>[] tab; Node<K,V> p; int n, i;
        if ((tab = table) == null || (n = tab.length) == 0)
            n = (tab = resize()).length;
        if ((p = tab[i = (n - 1) & hash]) == null)
            tab[i] = newNode(hash, key, value, null);
        else {
            Node<K,V> e; K k;
            if (p.hash == hash &&
                ((k = p.key) == key || (key != null && key.equals(k))))
                e = p;
            else if (p instanceof TreeNode)
                e = ((TreeNode<K,V>)p).putTreeVal(this, tab, hash, key, value);
            else {
                for (int binCount = 0; ;   binCount) {
                    if ((e = p.next) == null) {
                        p.next = newNode(hash, key, value, null);
                        if (binCount >= TREEIFY_THRESHOLD - 1) // -1 for 1st
                            treeifyBin(tab, hash);
                        break;
                    }
                    if (e.hash == hash &&
                        ((k = e.key) == key || (key != null && key.equals(k))))
                        break;
                    p = e;
                }
            }
            if (e != null) { // existing mapping for key
                V oldValue = e.value;
                if (!onlyIfAbsent || oldValue == null)
                    e.value = value;
                afterNodeAccess(e);
                return oldValue;
            }
        }
          modCount;
        if (  size > threshold)
            resize();
        afterNodeInsertion(evict);
        return null;
    }



Node<K,V> newNode(int hash, K key, V value, Node<K,V> next) {
        return new Node<>(hash, key, value, next);
    }

Node的构造方法

        Node(int hash, K key, V value, Node<K,V> next) {
            this.hash = hash;
            this.key = key;
            this.value = value;
            this.next = next;
        }