Re: ipc-msg broken again on 3.11-rc7? (was Re: linux-next: Tree for Jun 21 [ BROKEN ipc/ipc-msg ])

[Sedat Dilek <sedat.dilek@gmail.com>]

On Thu, Aug 29, 2013 at 9:21 AM, Vineet Gupta
<Vineet.Gupta1@synopsys.com> wrote:
> On 08/29/2013 08:34 AM, Sedat Dilek wrote:
>> On Wed, Aug 28, 2013 at 1:58 PM, Vineet Gupta
>> <Vineet.Gupta1@synopsys.com> wrote:
>>> Hi David,
>>>
>>> On 06/26/2013 04:59 AM, Davidlohr Bueso wrote:
>>>> On Tue, 2013-06-25 at 23:41 +0200, Sedat Dilek wrote:
>>>>> On Tue, Jun 25, 2013 at 10:33 PM, Davidlohr Bueso
>>>>> <davidlohr.bueso@hp.com> wrote:
>>>>>> On Tue, 2013-06-25 at 18:10 +0200, Sedat Dilek wrote:
>>>>>> [...]
>>>>>>
>>>>>>> I did some more testing with Linux-Testing-Project (release:
>>>>>>> ltp-full-20130503) and next-20130624 (Monday) which has still the
>>>>>>> issue, here.
>>>>>>>
>>>>>>> If I revert the mentioned two commits from my local
>>>>>>> revert-ipc-next20130624-5089fd1c6a6a-ab9efc2d0db5 GIT repo, everything
>>>>>>> is fine.
>>>>>>>
>>>>>>> I have tested the LTP ***IPC*** and ***SYSCALLS*** testcases.
>>>>>>>
>>>>>>>    root# ./runltp -f ipc
>>>>>>>
>>>>>>>    root# ./runltp -f syscalls
>>>>>> These are nice test cases!
>>>>>>
>>>>>> So I was able to reproduce the issue with LTP and manually running
>>>>>> msgctl08. We seemed to be racing at find_msg(), so take to q_perm lock
>>>>>> before calling it. The following changes fixes the issue and passes all
>>>>>> 'runltp -f syscall' tests, could you give it a try?
>>>>>>
>>>>> Cool, that fixes the issues here.
>>>>>
>>>>> Building with fakeroot & make deb-pkg is now OK, again.
>>>>>
>>>>> The syscalls/msgctl08 test-case ran successfully!
>>>> Andrew, could you pick this one up? I've made the patch on top of
>>>> 3.10.0-rc7-next-20130625
>>> LTP msgctl08 hangs on 3.11-rc7 (ARC port) with some of my local changes. I
>>> bisected it, sigh... didn't look at this thread earlier :-( and landed into this.
>>>
>>> ------------->8------------------------------------
>>> 3dd1f784ed6603d7ab1043e51e6371235edf2313 is the first bad commit
>>> commit 3dd1f784ed6603d7ab1043e51e6371235edf2313
>>> Author: Davidlohr Bueso <davidlohr.bueso@hp.com>
>>> Date:   Mon Jul 8 16:01:17 2013 -0700
>>>
>>>     ipc,msg: shorten critical region in msgsnd
>>>
>>>     do_msgsnd() is another function that does too many things with the ipc
>>>     object lock acquired.  Take it only when needed when actually updating
>>>     msq.
>>> ------------->8------------------------------------
>>>
>>> If I revert 3dd1f784ed66 and 9ad66ae "ipc: remove unused functions" - the test
>>> passes. I can confirm that linux-next also has the issue (didn't try the revert
>>> there though).
>>>
>>> 1. arc 3.11-rc7 config attached (UP + PREEMPT)
>>> 2. dmesg prints "msgmni has been set to 479"
>>> 3. LTP output (this is slightly dated source, so prints might vary)
>>>
>>> ------------->8------------------------------------
>>> <<<test_start>>>
>>> tag=msgctl08 stime=1377689180
>>> cmdline="msgctl08"
>>> contacts=""
>>> analysis=exit
>>> initiation_status="ok"
>>> <<<test_output>>>
>>> ------------->8-------- hung here ------------------
>>>
>>>
>>> Let me know if you need more data/test help.
>>>
>> Cannot say much to your constellation as I had the issue on x86-64 and
>> Linux-next.
>> But I have just seen a post-v3.11-rc7 IPC-fix in [1].
>>
>> I have here a v3.11-rc7 kernel with drm-intel-nightly on top... did not run LTP.
>
> Not sure what you mean - I'd posted that Im seeing the issue on ARC Linux (an FPGA
> board) 3.11-rc7 as well as linux-next of yesterday.
>

I am not saying there is no issue, but I have no possibility to test
for ARC arch.

>> Which LTP release do you use?
>
> The LTP build I generally use is from a 2007 based sources (lazy me). However I
> knew this would come up so before posting, I'd built the latest from buildroot and
> ran the msgctl08 from there standalone and it did the same thing.
>

Try always latest LTP-stable (03-May-2013 is what I tried). AFAICS a
new release is planned soon.

>> Might be good to attach your kernel-config for followers?
>
> It was already there in my orig msg - you probably missed it.
>

I have got that response from you only :-).

>> [1] http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=368ae537e056acd3f751fa276f48423f06803922
>
> I tried linux-next of today, same deal - msgctl08 still hangs.
>

That above fix [1] in Linus-tree is also in next-20130828.

Hope Davidlohr and fellows can help you.

- Sedat -