Is it ever OK to do g4/g5 to remove a knight pin?

This position has come up so many times it is not even funny.

My question is, in the above scenario is it ever ok to move to g4? Or in similar scenarios? I watched a grandmaster who said he told his students to never under any circumstance to do that move, but I sometimes do it in game and stockfish marks it as excellent.

Sure. Sometimes it's a horrible idea, and sometimes it's the best move you've got.

In the general sort of position pictured above, White has other options for relieving the pin, of course.

Something like c2-c3 (to stop Black from playing Nd4 and ganging up on the pinned Knight) followed by Re1 (to clear the f1-square), then N(b1)-d2-f1-g3 kicking the Bishop away.

Thank you! Very helpful!

Things to consider before playing g4(g5), assuming that you can’t tolerate the pin anymore:
(1) Is the opponent able to attack my weakened kingside? Two typical options for black(white) are the Nxg4(g5) sac and h7-h5 pawn break. This should be the primary concern if you have already castled kingside.
(2) Does this move create any weak “hole” (f4 in the position above, for example) in my structure? If yes, what can I do to prevent my opponent from exploiting this?
(3) Is there a “gentle approach” to break the pin that doesn’t weaken my structure so much? As @blueemu suggested, you can transfer the b1-knight to kingside via Nd2-f1-g3. Mild approaches, if exists, are usually preferable, though a direct g2-g4 can work out well if it’s the only thing you have.
(4) Can I make use of the aggression and start a kingside attack? This is possible when your king is not on the kingside. Such attacks usually involve a powerful knight on f5(f4), which is supported by the advance of your g-pawn.

g4(g5) is fine when you have good answers to the questions above.

One way or another, it's usually part of a larger plan involving kingside action. Like getting a knight to f5, or playing h5 and g5. Stuff like that.

Because black isn't castled kingside yet, and because black can remove your bishop with Na5, (and because you are castled kingside, so opening lines there might be risky) I wouldn't play g4 yet.

Maybe it will be good in the future, but there's no need to make that commitment right now. Part of a strong attack is center control and development. Once you have that you'll be able to make a better judgement about whether you want to play g4 or not.

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But lets make little changes to the position you posted.

 - If a3 were already played (ready to preserve the bishop against Na5) or

 - If white weren't castled yet or

 - If black had a kingside structural defect like he'd played h6

This would make g4 a more attractive idea.

But yeah, castling and playing h3+g4 within the first 7 moves of the game? Probably not.

Thank you everybody, you have all been so helpful.

Put the queen knight on d2 to defend the f3 knight. Then you can move the queen away from the bishop pin without your kingside pawns getting disrupted.

I'd only play g2-g4 if I was castled queenside. Or if the queens were off the board. Otherwise, it's asking for trouble.

https://www.chess.com/forum/view/chess-openings/why-not-g4-after-bh5-2018-11-03

Oh yeah, I remember that topic.

I was stiggling in that topic. Made a long post.

Kudos on winning one of the 24 hour blitz arenas. Very impressive.

You've got to be sure Black can't rip open your Kings' defences, because if that happens you'll be a SittingDucky.

Yes. Very often it creates no weakness at all

Thank you for the analogy.

Thanks