Re: Crash in __netif_receive_skb
From: Avleen Vig
Date: Thu Mar 29 2012 - 17:43:01 EST
On Wed, Mar 28, 2012 at 10:01 PM, Avleen Vig <avleen@xxxxxxxxx> wrote:
> On Wed, Mar 28, 2012 at 8:31 PM, Avleen Vig <avleen@xxxxxxxxx> wrote:
>> Hi folks, someone in #kernel recommended I email these two lists. Hope
>> they're the right place.
>> We're running 2.6.32-220.4.1.el6.x86_64 on Centos 6.2, and getting a
>> repeated crash:
>> We can make this happen pretty easily just by passing some network
>> traffic and waiting a while.
>> I couldn't find any references to this particular issue.
>> I have vmcore files and am happy to dig into it if it would help (as
>> long as someone can tell me what to do :))
> I hope this debugging is legit, I'm really new to this level of insight.
> I think the problem is in include/linux/netpoll.h, at the "if"
> statement at line 86:
> static inline int netpoll_receive_skb(struct sk_buff *skb)
> if (!list_empty(&skb->dev->napi_list))
> return netpoll_rx(skb);
> return 0;
> This is based on poking around in the crash dump:
> BUG: unable to handle kernel NULL pointer dereference at 0000000000000060
> IP: [<ffffffff8142bb40>] __netif_receive_skb+0x60/0x6e0
> crash> dis -rl ffffffff8142bb40
> 0xffffffff8142bb33 <__netif_receive_skb+83>: mov 0x20(%rbx),%r12
> 0xffffffff8142bb37 <__netif_receive_skb+87>: mov %r12,-0x38(%rbp)
> 0xffffffff8142bb3b <__netif_receive_skb+91>: lea 0x60(%r12),%rax
> 0xffffffff8142bb40 <__netif_receive_skb+96>: cmp %rax,0x60(%r12)
> I *think* this means that "&skb->dev->napi_list" is null when we're
> trying to compare it, rather than being a list.
> If it matters, this is inside LXC containers.
We've traced this to a problem with machines that have multiple hard
drives AND have NAPI enabled for the NIC driver.
We recompiled the e1000e driver with NAPI disabled, with:
and everything works great now.
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