[Opensound-devel] cuckoo debugging - page deallocation bug

[Igor K. <ik...@ya...>]

Hi,

I'm currently doing some hacking in the cuckoo module (as in 
http://www.opensound.com/forum/viewtopic.php?t=5588). I've been trying 
to debug a particular problem that left me stumped.

When I use alsa-lib through a plug PCM (linear/sample rate etc. 
conversion), upon closing the PCM I get several "bad page state" errors 
from the kernel:

[  433.089585] BUG: Bad page state in process aplay  pfn:b3778
[  433.089588] page:ffffea0002cdde00 count:0 mapcount:0 mapping: 
   (null) index:0x0
[  433.089589] page flags: 0x100000000000414(referenced|dirty|reserved)
(...)

Except for the dmesg messages, it causes no further problems.
The number of bad pages is directly proportional to the DMA buffer size 
used by ALSA, minus one. The only vaguely related problem of this nature 
I could find is http://lkml.org/lkml/2011/8/31/71. Could my problem be 
caused by ALSA using a different deallocation method somewhere?

I'm using kernel 3.8.12 with SLUB allocator and alsa 1.0.27.2.