user24016: I have problems when black places his bishop on d6 in the London. Take for instance the following game:
r1bq1rk1/p2n1ppp/2n1p3/1p1pP3/2p5/2P1P1B1/PPBN1PPP/R2QK2R w KQ - 1 12
1. d4 d5 2. Bf4 { D00 Queen's Pawn Game: Mason Variation } e6 3. e3 Bd6 4. Bg3 Nf6 5. Bd3 O-O 6. Nd2 c5 7. c3 c4 8. Bc2 Nc6 9. Ngf3 b5 10. Ne5 Bxe5 11. dxe5 Nd7 

The question of what to do with ...Bd6 comes already in movement 4. Theory advises White to avoid taking it, as that will bring Black's Queen into play. Instead, White should retreat his bishop to g3, or even leave it on f4. First problem is, with the bishop in g3, White can't castle kingside while the d6-g3 diagonal is open.
The second problem is that placing a piece on e5 should be White's main plan with the London, but with Black's bishop on d6, that's not possible, as Black can exchange any piece post there by White. Even worse, if White ends up with a pawn there, as in this game, this pawn will end up being very hard to defend for White. Or it will have to be defended with f2-f4, weakening White's kingside and blocking White's bishop if it's still on g3.
So my question is how to deal with Black's bishop on d6 addressing these two problems?

user11144: I play London all the time (even before it was called this way, and I don't even intend to play the Lamer London variant, consisting of kingside overrunning the poor sap who hasn't learnt opening theory :-) and you make a few implicite assumptions I have object to.
"bring Black's Queen into play...". True, but that's hardly the point. The point is the following break e5, and Black has solved all his problems, especially the Bc8. Thus indeed noone ever exchanges, OR only exchanges if the break e5 can be blocked forever (maybe with f4).
"White should retreat his bishop to g3..." Possible. "White can't castle kingside while the d6-g3 diagonal is open." Strong objection. Nothing wrong with that, even the nonstandard fxg3 following the exchange Bxg3 should always be considered. An attack along the standard scheme Ng4, Qh5 against this structure is very far into the future.
"or even leave it on f4..."" Possible. Many, many opponents had to suffer against me after Bxf4 (now e5 is completely out of question, have fun countering N-f3-e5, R-e1-e3-h3 and other lovelies). And none of them ever played Qd6 followed by Qb4 with a double attack on d4 and b2 when I was an idiot and it was possible. :-)
"Or it will have to be defended with f2-f4, weakening White's kingside and blocking White's bishop if it's still on g3." Objection, no problems with that either. Play Bf2 followed by e4, for example. Black has a real problem on the black squares now that the bishop is gone. A weakened king side is only relevant if the opponent can attack it. How?
And his usual London problem, lack of space, still remains.
Coda: Neither of your two problems seem to be a problem to me.
Addendum: The early 7...c4 seems a severe strategic error to me.

24016: <p>I have problems when black places his bishop on d6 in the London. Take for instance the following game:</p>
<pre><code>r1bq1rk1/p2n1ppp/2n1p3/1p1pP3/2p5/2P1P1B1/PPBN1PPP/R2QK2R w KQ - 1 12
1. d4 d5 2. Bf4 { D00 Queen's Pawn Game: Mason Variation } e6 3. e3 Bd6 4. Bg3 Nf6 5. Bd3 O-O 6. Nd2 c5 7. c3 c4 8. Bc2 Nc6 9. Ngf3 b5 10. Ne5 Bxe5 11. dxe5 Nd7 
</code></pre>
<p>The question of what to do with ...Bd6 comes already in movement 4. Theory advises White to avoid taking it, as that will bring Black's Queen into play. Instead, White should retreat his bishop to g3, or even leave it on f4. First problem is, with the bishop in g3, White can't castle kingside while the d6-g3 diagonal is open.</p>
<p>The second problem is that placing a piece on e5 should be White's main plan with the London, but with Black's bishop on d6, that's not possible, as Black can exchange any piece post there by White. Even worse, if White ends up with a pawn there, as in this game, this pawn will end up being very hard to defend for White. Or it will have to be defended with f2-f4, weakening White's kingside and blocking White's bishop if it's still on g3.</p>
<p>So my question is how to deal with Black's bishop on d6 addressing these two problems?</p>
 11144: <p>I play London all the time (even before it was called this way, and I don't even intend to play the Lamer London variant, consisting of kingside overrunning the poor sap who hasn't learnt opening theory :-) and you make a few implicite assumptions I have object to.</p>
<p><I>&quot;bring Black's Queen into play...&quot;</I>. True, but that's hardly the point. The point is the following break e5, and Black has solved all his problems, especially the Bc8. Thus indeed noone ever exchanges, OR only exchanges if the break e5 can be blocked forever (maybe with f4).</p>
<p><I>&quot;White should retreat his bishop to g3...&quot;</I> Possible. <I>&quot;White can't castle kingside while the d6-g3 diagonal is open.&quot;</I> Strong objection. Nothing wrong with that, even the nonstandard fxg3 following the exchange Bxg3 should always be considered. An attack along the standard scheme Ng4, Qh5 against this structure is very far into the future.</p>
<p><I>&quot;or even leave it on f4...&quot;</I>&quot; Possible. Many, many opponents had to suffer against me after Bxf4 (now e5 is completely out of question, have fun countering N-f3-e5, R-e1-e3-h3 and other lovelies). And none of them ever played Qd6 followed by Qb4 with a double attack on d4 and b2 when I was an idiot and it was possible. :-)</p>
<p><I>&quot;Or it will have to be defended with f2-f4, weakening White's kingside and blocking White's bishop if it's still on g3.&quot;</I> Objection, no problems with that either. Play Bf2 followed by e4, for example. Black has a real problem on the black squares now that the bishop is gone. A weakened king side is only relevant if the opponent can attack it. How?
And his usual London problem, lack of space, still remains.</p>
<p>Coda: Neither of your two problems seem to be a problem to me.</p>
<p>Addendum: The early 7...c4 seems a severe strategic error to me.</p>
