Re: List corruption on epoll_ctl(EPOLL_CTL_DEL) an AF_UNIX socket

From: Mathias Krause
Date: Wed Sep 30 2015 - 07:56:05 EST

On 30 September 2015 at 12:56, Rainer Weikusat
<rweikusat@xxxxxxxxxxxxxxxxxxxxxxx> wrote:
> Mathias Krause <minipli@xxxxxxxxxxxxxx> writes:
>> On 29 September 2015 at 21:09, Jason Baron <jbaron@xxxxxxxxxx> wrote:
>>> However, if we call connect on socket 's', to connect to a new socket 'o2', we
>>> drop the reference on the original socket 'o'. Thus, we can now close socket
>>> 'o' without unregistering from epoll. Then, when we either close the ep
>>> or unregister 'o', we end up with this list corruption. Thus, this is not a
>>> race per se, but can be triggered sequentially.
>> Sounds profound, but the reproducers calls connect only once per
>> socket. So there is no "connect to a new socket", no?
>> But w/e, see below.
> In case you want some information on this: This is a kernel warning I
> could trigger (more than once) on the single day I could so far spend
> looking into this (3.2.54 kernel):
> Sep 15 19:37:19 doppelsaurus kernel: WARNING: at lib/list_debug.c:53 list_del+0x9/0x30()
> Sep 15 19:37:19 doppelsaurus kernel: Hardware name: 500-330nam
> Sep 15 19:37:19 doppelsaurus kernel: list_del corruption. prev->next should be ffff88022c38f078, but was dead000000100100
> [snip]

Is that with Jason's patch or a vanilla v3.2.54?

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