Re: kernel BUG at include/linux/list.h:164!

[Konstantin Kletschke]

Am 2004-05-02 09:22 +0100 schrieb Hugh Dickins:
> On Sat, 1 May 2004, Konstantin Kletschke wrote:
> > 
> > May  1 12:03:07 kermit kernel: kernel BUG at include/linux/list.h:164!
> > May  1 12:03:07 kermit kernel: invalid operand: 0000 [#1]
> > May  1 12:03:07 kermit kernel: PREEMPT
> > May  1 12:03:07 kermit kernel: CPU:    0
> > May  1 12:03:07 kermit kernel: EIP:    0060:[exit_rmap+237/272] Not tainted VLI
> > May  1 12:03:07 kermit kernel: EFLAGS: 00010283   (2.6.6-rc2-mm1)
> ....
> > 2.6.6-rc2-mm1 with devmapper udm1 patch
> > 
> > Is this dump due to udma1 or not and the error is fixed now?
> 
> Probably not - I don't know this udma1 patch, but the error above

It provides snapshot and pvmove functionality for LVM2 and 2.6.x
kernels and is in the early creation if I understood right...

> definitely occurs in my rmap area.

HA! :)

> though neither my testing nor anyone else has seen the same (yet).

Ok, lets see...

> I imagine you're limited in the experiments you can do on that server,
> and wouldn't want to run it with CONFIG_SLAB_DEBUG=y, which might show
> up unrelated problems - interesting for us, but troublesome for you.

Yes, sadly :(

> You're UP but PREEMPT on.  Hmm, there's a suspicious atomic_read
> in exit_rmap: once upon a time I convinced myself it was good, but
> it looks unsafe to me now - could cause a double free of an anonmm,
> which would lead to your BUG if reallocated in between.
> 
> Not so likely for me to feel this is definitely the answer, but
> likely enough to be well worth trying.  Please try patch below -
> simple enough not to make your case worse anyway - thanks.

Ok, I will try that out and incorporate the patch tomorrow. Works on
test machine fine so far (and compiles of course :P). Then we will
see, if the uptime lasts longer...

reHugh

-- 
2.6.5-mm1
Konstantin Kletschke <konsti@xxxxxxxxxxxxx>, <konsti@xxxxxxxxx>
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