Re: slab corruption in skb allocs

[Andrew Morton]

Richard Fuchs <richard.fuchs@xxxxxxxxxx> wrote:
>
> hello all!
> 
> the memory allocation debugger gives me the following messages under a
> vanilla 2.6.10 and 2.6.11 kernel when doing
> 
> 1) hdparm -d0 on my hard disk
> 2) tar c / > /dev/null
> 3) sending lots of network traffic to the machine (e.g. close to 100
> mbit/s udp packets)
> 
> -----------------------------------------------------
> Slab corruption: start=de9141a4, len=2048
> Redzone: 0x5a2cf071/0x5a2cf071.
> Last user: [<c03b8163>](kfree_skbmem+0x13/0x30)
> 010: 6b 6b 20 a0 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 3b c0
> 020: 6b 6b 00 0b cd 1e 1f d2 00 04 23 01 c7 6f 81 00
> 030: 00 df 08 00 45 00 00 1c 41 d0 40 00 40 11 33 78
> 040: c0 a8 22 1d c0 a8 22 1b 80 52 30 18 00 08 89 ea
> 050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 6b 6b
> ...
> 
> and so on. the disk activity alone or the network traffic alone doesn't
> trigger this. also doing the same with dma enabled doesn't trigger this
> either, but when everything comes together i get this within a second.
> kernel is not smp and preempt is not enabled.
> 
> kernel config (from 2.6.11) is attached; if you need any more info, let
> me know. is this a kernel issue, or could the hardware be at fault?

I guess it could be hardware.  But given that disabling DMA _causes_ the
problem, rather than fixes it, it seems unlikely.

Could you enable CONFIG_DEBUG_PAGEALLOC in .config and see it that triggers
an oops?

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