Re: PROBLEM: kernel BUG at mm/slab.c:3002!

["Alan D. Brunelle" <Alan.Brunelle@hp.com>]

Matt Mackall wrote:
> On Tue, 2009-03-10 at 13:29 -0400, Alan D. Brunelle wrote:
>> Matt Mackall wrote:
>>> On Tue, 2009-03-10 at 11:16 -0400, Alan D. Brunelle wrote:
>>>> Running blktrace & I/O loads cause a kernel BUG at mm/slab.c:3002!.
>>> Pid: 11346, comm: blktrace Tainted: G    B      2.6.29-rc7 #3 ProLiant
>>> DL585 G5   
>>>
>>> That 'B' there indicates you've hit 'bad page' before this. That bug
>>> seems to be strongly correlated with some form of hardware trouble.
>>> Unfortunately, that makes everything after that point a little suspect.
>>
>> /If/ it were a hardware issue, that might explain the subsequent issue
>> when I switched to SLUB instead...
> 
> Well it was almost certainly not a bug in SLAB itself (and your SLUB
> test is obviously quite conclusive there). We'd have lots of reports.
> It's probably too early to conclude it's hardware though.
> 
>> How does one look for "bad page reports"?
> 
> It'll look something like this (pasted from Google):
> 
>>>     kernel: Bad page state at free_hot_cold_page (in process 'beam',
>>> page c1a95320)
>>>     kernel: flags:0x40020118 mapping:f401adc0 mapped:0 count:0
>>> private:0x00000000
> 

Interestingly enough, I'm not seeing the kernel detect such things - but
in going into the hardware server logs, a co-worker found "unrecoverable
system errors" being detected at about the same times we're seeing the
panics.

We're investigating hardware issues now, if those don't pan out, I'll
continue looking at possible software memory corruptors...

Alan


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