I always hear "A long password is good, a longer password is better". But is there such a thing as a "**Password is so long it is becoming unsafe**" or "**Password is long enough, making it longer won't matter**"?

I am interested in the security of the password regarding cracking it only.  
Not if it [can cause a DoS][1] overload the servers while hashing, or if [the vendor thinks otherwise][2].

Also assume the password does not contain any [dictionary <sub>it'd be in comments anyway.</sub>][3] words, is [stored using best practices][4], has a strong and [unique salt][5], and [relevant entropy][6] per character. How the user will remember / recall / store the password also doesn't matter. 

I agree that [longer][7] / [passwords][8] / [are safer][9]. I'm asking about the **upper** limit.

Is there a length (or entropy size) where making the password longer no longer (sic) matter, or even weakens its security? I know it depends on the hashing algorithm, if the upper limit for a given algorithm exists and is known, what is it?


  [1]: http://arstechnica.com/security/2013/09/long-passwords-are-good-but-too-much-length-can-be-bad-for-security/
  [2]: http://www.networkworld.com/article/2222973/microsoft-subnet/microsoft-account-password--16-characters-is-too-long-to-protect-outlook-com---skyd.html
  [3]: http://xkcd.com/936/
  [4]: https://www.nccgroup.trust/us/about-us/newsroom-and-events/blog/2015/march/enough-with-the-salts-updates-on-secure-password-schemes/
  [5]: https://security.stackexchange.com/questions/73588/does-too-long-a-salt-reduce-the-security-of-a-stored-password-hash
  [6]: http://blog.codinghorror.com/your-password-is-too-damn-short/
  [7]: https://security.stackexchange.com/questions/16840/long-passwords-how-are-they-more-secure
  [8]: https://security.stackexchange.com/questions/115680/are-longer-passwords-safer-even-if-the-encryption-database-security-used-is-comp
  [9]: https://security.stackexchange.com/questions/6095/xkcd-936-short-complex-password-or-long-dictionary-passphrase