lkml.org 
[lkml]   [2017]   [Jul]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [lkp-robot] [x86/refcount] b631e535c6: WARNING:at_net/netlink/af_netlink.c:#netlink_sock_destruct
On Tue, Jul 25, 2017 at 11:38:30AM -0700, Kees Cook wrote:
>On Tue, Jul 25, 2017 at 3:43 AM, Hans Liljestrand
><liljestrandh@gmail.com> wrote:
>> On Mon, Jul 24, 2017 at 08:21:16PM -0700, Kees Cook wrote:
>>>
>>> On Mon, Jul 24, 2017 at 6:03 AM, Hans Liljestrand
>>> <liljestrandh@gmail.com> wrote:
>>>>
>>>> On Sun, Jul 23, 2017 at 08:52:53PM -0700, Kees Cook wrote:
>>>>>
>>>>>
>>>>> Is 14afee4b6092f ("net: convert sock.sk_wmem_alloc from atomic_t to
>>>>> refcount_t") correct? That looks like a statistics counter, not a
>>>>> refcounter? I can't quite tell, though...
>>>>
>>>>
>>>>
>>>> Hmm, yes, it looks a bit weird, but it is used in a refcount fashion
>>>> here:
>>>>
>>>> void sk_free(struct sock *sk)
>>>> {
>>>> /*
>>>> * We subtract one from sk_wmem_alloc and can know if
>>>> * some packets are still in some tx queue.
>>>> * If not null, sock_wfree() will call __sk_free(sk) later
>>>> */
>>>> if (refcount_dec_and_test(&sk->sk_wmem_alloc))
>>>> __sk_free(sk);
>>>> }
>>>>
>>>> http://elixir.free-electrons.com/linux/v4.13-rc1/source/net/core/sock.c#L1605
>>>
>>>
>>> Ah yeah, there it is. Hrmpf. Something is triggering WARNs, though...
>>> I wonder if this can get examined more closely?
>>
>>
>> I tried reproducing the error but I don't seem to know how to use lkp. Got
>> lots of permission denied errors and finally ran out of disk space (after
>> using up ~50GB).
>>
>> Maybe I did something wrong?
>>
>> What I did was: Cloned the related kernel repository, checked out offending
>> commit, plopped in config, compiled bzImage. Then I just cloned the lkp repo
>> and tried running the provided command line with the bzImage and provided
>> script.
>>
>> I'll take another look once I have the time, might be I missed something
>> earlier.
>
>Yeah, I'm not sure. Seems it was found through trinity? And only after
>36 seconds, too.

I think I might have missed something here? I cannot find anything about
trinity or 36 seconds? Although I either misplaced or didn't get the original
email, so I'm not sure if it had some other attachments beyond the config and
script?

>
>>> Also, why not atomic->refcount for sk_rmem_alloc?
>>
>> I couldn't find any similar refcount-like use on sk_rmem_alloc.
>
>Okay, interesting.
>
>> And as noted the sk_wmem_alloc thing is also a bit dubious. It looks like it
>> serves a dual purpose of actual allocation size and occasional reference
>> counter.
>
>Could you ask net-dev to see what is actually happening here? This
>looks like a regression, but also very odd (broken?) refcounting ...

Sure, but I'm unsure of what exactly I should be asking? If you have any more
information on the trinity results I'd be happy to look at that beforehand?

Thanks,
-hans

>
>-Kees
>
>
>--
>Kees Cook
>Pixel Security

\
 
 \ /
  Last update: 2017-07-27 15:35    [W:0.052 / U:6.540 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site