I get this on the latest GIT, it was also present shortly after -rc1.
I have not tested with earlier kernels.
# brctl stp br0 on
[ 169.672008] BUG: sleeping function called from invalid context at kernel/mutex.c:86
[ 169.672532] in_atomic():1, irqs_disabled():0
[ 169.672832]
[ 169.672832] Call Trace:
[ 169.673406] [<ffffffff8125db3a>] mutex_lock+0x19/0x2f
[ 169.673696] [<ffffffff81067135>] __alloc_pages+0x71/0x2d3
[ 169.673996] [<ffffffff881e0abc>] :bridge:set_stp_state+0x12/0x37
[ 169.674293] [<ffffffff881e0a0a>] :bridge:store_bridge_parm+0x5f/0x79
[ 169.674587] [<ffffffff810ceb24>] sysfs_write_file+0xf2/0x134
[ 169.674879] [<ffffffff8108b3ad>] vfs_write+0xce/0x177
[ 169.675170] [<ffffffff8108b970>] sys_write+0x45/0x6e
[ 169.675463] [<ffffffff8100bc8e>] system_call+0x7e/0x83
[ 169.675769]
[ 169.676139] br0: starting userspace STP failed, staring kernel STP
# brctl stp br0 off
[ 171.774500] BUG: sleeping function called from invalid context at kernel/mutex.c:86
[ 171.775040] in_atomic():1, irqs_disabled():0
[ 171.775327]
[ 171.775328] Call Trace:
[ 171.775906] [<ffffffff8125db3a>] mutex_lock+0x19/0x2f
[ 171.776195] [<ffffffff81067135>] __alloc_pages+0x71/0x2d3
[ 171.776496] [<ffffffff881e0abc>] :bridge:set_stp_state+0x12/0x37
[ 171.776792] [<ffffffff881e0a0a>] :bridge:store_bridge_parm+0x5f/0x79
[ 171.777086] [<ffffffff810ceb24>] sysfs_write_file+0xf2/0x134
[ 171.777378] [<ffffffff8108b3ad>] vfs_write+0xce/0x177
[ 171.777669] [<ffffffff8108b970>] sys_write+0x45/0x6e
[ 171.777958] [<ffffffff8100bc8e>] system_call+0x7e/0x83
[ 171.778250]
Daniel K.