Jesper Dangaard Brouer wrote:

Hi Patrick,

Bisected me down to one of you changes
 commit 6c78dcbd47a68a
 [VLAN]: Fix promiscous/allmulti synchronization races

Description:
------------
 All other VLAN interfaces stop working, if a vlan is taken down
 (ifconfig eth1.1025 down) _while_ there is a tcpdump running on that
 interface.

 The problem is a result of promisc mode being removed on the
 real-device (eth1), when the vlan interface is taken down.  This
 should not happen as other vlan devices exists that still need
 promisc mode on the real-device (eth1).

I'm pretty sure we fixed this already in commit 0ed21b32.