Re: Debugging memory allocation

[Paul M. <le...@li...>]

On Sat, Oct 06, 2007 at 03:19:10PM +0100, Adrian McMenamin wrote:
> On Thu, 2007-10-04 at 19:32 +0900, Paul Mundt wrote:
> > On Wed, Sep 12, 2007 at 08:50:33PM +0100, Adrian McMenamin wrote:
> > > I don't know if this is just G2 flakiness, but if I start playing sound
> > > and then start hotplugging devices then I will sometimes get this sort
> > > of oops (these don't down the system but they can make it unstable) -
> > > any clues as to what might be the issue (these are now quite old -rc2?
> > > kernels...)... just wondering if anybody can see anything obvious?
> > > 
> > > [   95.916012] Maple bus detaching at (0, 2)
> > > [   96.208858] Unable to handle kernel paging request at virtual address
> > > dfff0800
> > > [   96.215707] pc = 8c00e480
> > > [   96.218317] *pde = 00000000
> > > [   96.221194] Oops: 0001 [#1]
> > > [   96.224005] Modules linked in: snd_aica snd_pcm_oss snd_pcm snd_timer
> > > snd_page_alloc snd_mixer_oss snd soundcore maple_keyb
> > > [   96.235500] 
> > > [   96.237035] Pid : 1842, Comm:                    [
> > > [   96.241993] PC is at __copy_user_page+0x28/0x54
> > 
> > You've faulted on a fixmap slot, perhaps you've hit a race with the page
> > colouring code. Can you try with write-through caching enabled?
> 
> Doesn't want to work....
> 
>     1.689829] BUG: FPU is used in kernel mode.
> [    1.694764] unaligned program counter: 00e0 [#1]
> [    1.700040] Modules linked in:
> [    1.703529] 
> [    1.705268] PC  : 7bffffff SP  : 8c2edbe8 SR  : 400080f0 TEA :
> 7bffffff    unaligned program counter: 00e0 [#2]
> [    1.716833] Modules linked in:
> [    1.720323] 

A recursive oops even, great. Write-through works fine on all of my 2-way
and 4-way set associative dcaches, you're probably the only user of
direct-mapped SH caches these days. I'll see if I can dig up a board with
a direct-mapped cache or see if this is reproducable with EMODE disabled
on 2-way.

Does disabling the dcache work for you?