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Message-ID: <CAMjP1KmDxhOKOGtgKt=OWbcXoJgrbA_rAxdkV4j7Y8XC8yjnuA@mail.gmail.com> Date: Wed, 28 Mar 2012 22:01:49 -0500 From: Avleen Vig <avleen@...il.com> To: linux-kernel@...r.kernel.org, netdev@...r.kernel.org Subject: Re: Crash in __netif_receive_skb On Wed, Mar 28, 2012 at 8:31 PM, Avleen Vig <avleen@...il.com> 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: > https://gist.github.com/2231998 > > 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 .... /usr/src/debug/kernel-2.6.32-220.7.1.el6/linux-2.6.32-220.7.1.el6.x86_64/include/linux/netpoll.h: 86 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. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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