Re: Fw: [Bugme-new] [Bug 4628] New: Test server hang while running rhr (network) test on RHEL4 with kernel 2.6.12-rc1-mm4

[Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>]

Andrew Morton <akpm@xxxxxxxx> wrote:
> 
> Might be a bug in the e100 driver, might not be.
> 
> I assume this is the
> 
>        BUG_ON(skb->list != NULL);

It certainly is a bug in e100.

e100_tx_timeout -> e100_down -> e100_rx_clean_list

is racing against

e100_poll -> e100_rx_clean -> e100_rx_indicate

e100_rx_clean/e100_rx_indicate takes an skb off the RX ring and
while it's being processed e100_rx_clean_list comes along and
frees it.

From a quick check similar problems may exist in other drivers that
have lockless ->poll() functions with RX rings.

Cheers,
-- 
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