Re: [Opensound-devel] cuckoo debugging - page deallocation bug

[Hannu S. <ha...@op...>]

Hi,

It is impossible to say why this happens without knowing where it
happens. Can you send the stack trace that should be there after the BUG
message.

Best regards,

Hannu
---
4.2.2014 21.19, Igor Kotrasiński wrote:
> 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.
>
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