Re: freecad: Need help with segfault problem on F24

[Richard Shaw]

On Tue, May 3, 2016 at 3:17 PM, Przemek Klosowski <
przemek.klosow...@nist.gov> wrote:

> On 05/03/2016 03:54 PM, Richard Shaw wrote:
>
> the package that's causing the segfault (Coin3) is not part of the update
> but it causes a segfault in python-pivy regardless of whether you're
> running the old 0.15 package or new 0.16 package so I went ahead and pushed
> to stable so I could update f22/23, otherwise the version in f23/23 would
> be newer than that's in f24.
>
> On my two fully updated systems I have the following versions of Coin3:
> __  __V_  __R___  Built Installed
> Fedora 24: 3.1.3 16.fc24 Feb  3   Apr 2
> Fedora 23: 3.1.3 11.fc23 Jul 29   Dec 22
>
> so the new version didn't make it out yet. Would it help if we installed a
> version from koji/bodhi somewhere? if so, where is it?
>

Hence the BZ on Coin3. I'm technically a co-maintainer but Ralph didn't
appreciate my quick fix without including him so I stopped after performing
a build for Rawhide and I'm currently waiting for him to review the patch
used for Rawhide and apply it to f24 assuming it's appropriate.

Thanks,
Richard
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Re: freecad: Need help with segfault problem on F24

[Przemek Klosowski]

On 05/03/2016 03:54 PM, Richard Shaw wrote:
the package that's causing the segfault (Coin3) is not part of the 
update but it causes a segfault in python-pivy regardless of whether 
you're running the old 0.15 package or new 0.16 package so I went 
ahead and pushed to stable so I could update f22/23, otherwise the 
version in f23/23 would be newer than that's in f24.

On my two fully updated systems I have the following versions of Coin3:
__  __V_  __R___  Built Installed
Fedora 24: 3.1.3 16.fc24 Feb  3   Apr 2
Fedora 23: 3.1.3 11.fc23 Jul 29   Dec 22

so the new version didn't make it out yet. Would it help if we installed 
a version from koji/bodhi somewhere? if so, where is it?



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Re: freecad: Need help with segfault problem on F24

[Richard Shaw]

On Tue, May 3, 2016 at 2:50 PM, Przemek Klosowski <
przemek.klosow...@nist.gov> wrote:

> I am sligtly confused here (so what else is new :). *Bug 1153551*
>   seems to be
> brasero's "Cannot burn files from network drive".
> What am I missing?
>

I was task switching between several bugs that day and must have had the
wrong one for copy/paste, the correct bug is:

https://bugzilla.redhat.com/show_bug.cgi?id=1329814


Also, you comment ( https://bugzilla.redhat.com/show_bug.cgi?id=1323159#c50
> ) that the fix was pushed to f24 stable, but I don't see it in the update
> stream (my repolist is F24 fedora/updates/updates-testing). Should I be
> looking somewhere else? if so, can you send a link to the test RPM?
>

No, the package that's causing the segfault (Coin3) is not part of the
update but it causes a segfault in python-pivy regardless of whether you're
running the old 0.15 package or new 0.16 package so I went ahead and pushed
to stable so I could update f22/23, otherwise the version in f23/23 would
be newer than that's in f24.

Thanks,
Richard
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Re: freecad: Need help with segfault problem on F24

[Przemek Klosowski]

On 05/03/2016 02:16 PM, Richard Shaw wrote:
On Mon, Apr 25, 2016 at 3:15 PM, Richard Shaw > wrote:


On Fri, Apr 22, 2016 at 9:34 AM, Ralf Corsepius
> wrote:


How about
* filing a BZ against Coin3 such that the Coin3 maintainer
(me) gets informed and has a chance to reproduced the issue?


Done.

https://bugzilla.redhat.com/show_bug.cgi?id=1153551


Have you had any luck reproducing the issue and/or verifying the 
validity of the fix?
I am sligtly confused here (so what else is new :).***Bug 1153551* 
 seems to be 
brasero's "Cannot burn files from network drive".

What am I missing?

Also, you comment ( 
https://bugzilla.redhat.com/show_bug.cgi?id=1323159#c50 ) that the fix 
was pushed to f24 stable, but I don't see it in the update stream (my 
repolist is F24 fedora/updates/updates-testing). Should I be looking 
somewhere else? if so, can you send a link to the test RPM?
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Re: freecad: Need help with segfault problem on F24

[Richard Shaw]

On Mon, Apr 25, 2016 at 3:15 PM, Richard Shaw  wrote:

> On Fri, Apr 22, 2016 at 9:34 AM, Ralf Corsepius 
> wrote:
>
>>
>> How about
>> * filing a BZ against Coin3 such that the Coin3 maintainer (me) gets
>> informed and has a chance to reproduced the issue?
>>
>
> Done.
>
> https://bugzilla.redhat.com/show_bug.cgi?id=1153551
>

Have you had any luck reproducing the issue and/or verifying the validity
of the fix?

I sincerely hope you are not purposefully ignoring this bug report as I
have already apologized for my overzealousness and ignoring it only harms
users.

Thanks,
Richard
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Re: freecad: Need help with segfault problem on F24

[Richard Shaw]

On Fri, Apr 22, 2016 at 9:34 AM, Ralf Corsepius  wrote:

>
> How about
> * filing a BZ against Coin3 such that the Coin3 maintainer (me) gets
> informed and has a chance to reproduced the issue?
>

Done.

https://bugzilla.redhat.com/show_bug.cgi?id=1153551

Thanks,
Richard
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Re: freecad: Need help with segfault problem on F24

[Richard Shaw]

On Fri, Apr 22, 2016 at 9:34 AM, Ralf Corsepius  wrote:
>
> How about
> * filing a BZ against Coin3 such that the Coin3 maintainer (me) gets
> informed and has a chance to reproduced the issue?
>
> * filing and proposing a patch in advance, instead of rushing out patch?


Apologies, of course you are right. I just got so wrapped up into trying to
figure out what the problem is.

The fix (if appropriate) should also probably be sent to the upstream issue
tracker.

Thanks,
Richard
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Re: freecad: Need help with segfault problem on F24

[Ralf Corsepius]

On 04/22/2016 02:58 PM, Richard Shaw wrote:

On Fri, Apr 22, 2016 at 7:54 AM, Jonathan Wakely > wrote:

> Looks like Mamoru figured it out, thanks everyone for the help.
>
>https://bugzilla.redhat.com/show_bug.cgi?id=1323159#c34

I'm curious what the fix is :-)

All the bugzilla says is that the memhandler is null, which was
already apparent from the stacktrace. I'll have a look when the
patch lands in git.


Yeah, I was wondering why it's a problem in F24 but not F23 or before...
but the wait is over!


How about
* filing a BZ against Coin3 such that the Coin3 maintainer (me) gets 
informed and has a chance to reproduced the issue?


* filing and proposing a patch in advance, instead of rushing out patch?


http://pkgs.fedoraproject.org/cgit/rpms/Coin3.git/commit/?id=ca89ec7227943bdec800ee51b920f578fab87b05


Ralf
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Re: freecad: Need help with segfault problem on F24

[Jonathan Wakely]

On 22/04/16 07:58 -0500, Richard Shaw wrote:

On Fri, Apr 22, 2016 at 7:54 AM, Jonathan Wakely  wrote:


> Looks like Mamoru figured it out, thanks everyone for the help.
>
> https://bugzilla.redhat.com/show_bug.cgi?id=1323159#c34

I'm curious what the fix is :-)

All the bugzilla says is that the memhandler is null, which was already
apparent from the stacktrace. I'll have a look when the patch lands in git.



Yeah, I was wondering why it's a problem in F24 but not F23 or before...
but the wait is over!

http://pkgs.fedoraproject.org/cgit/rpms/Coin3.git/commit/?id=ca89ec7227943bdec800ee51b920f578fab87b05


It's a new optimization in F24's GCC 6, the "More aggressive
optimization of -flifetime-dse" change described at
https://gcc.gnu.org/gcc-6/porting_to.html
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Re: freecad: Need help with segfault problem on F24

[Richard Shaw]

On Fri, Apr 22, 2016 at 7:54 AM, Jonathan Wakely  wrote:

> > Looks like Mamoru figured it out, thanks everyone for the help.
> >
> > https://bugzilla.redhat.com/show_bug.cgi?id=1323159#c34
>
> I'm curious what the fix is :-)
>
> All the bugzilla says is that the memhandler is null, which was already
> apparent from the stacktrace. I'll have a look when the patch lands in git.


Yeah, I was wondering why it's a problem in F24 but not F23 or before...
but the wait is over!

http://pkgs.fedoraproject.org/cgit/rpms/Coin3.git/commit/?id=ca89ec7227943bdec800ee51b920f578fab87b05

Thanks,
Richard
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Re: freecad: Need help with segfault problem on F24

[Jonathan Wakely]

> Looks like Mamoru figured it out, thanks everyone for the help.
> 
> https://bugzilla.redhat.com/show_bug.cgi?id=1323159#c34

I'm curious what the fix is :-)

All the bugzilla says is that the memhandler is null, which was already 
apparent from the stacktrace. I'll have a look when the patch lands in git.
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Re: freecad: Need help with segfault problem on F24

[Jonathan Wakely]

On 22/04/16 07:36 -0500, Richard Shaw wrote:

On Fri, Apr 22, 2016 at 5:46 AM, Jonathan Wakely 
wrote:


On 21/04/16 08:00 -0500, Richard Shaw wrote:


Well it turns out -fsanitize=undefined made no difference in this case...

Here's the stacktrace:

http://paste.fedoraproject.org/358119/46124321/



allocator=0x0 is the problem there, that argument must be non-null.

It comes from:

   void operator delete(void * ptr) {
 SbHashEntry * entry = static_cast( ptr);
 cc_memalloc_deallocate(entry->memhandler, ptr);
   }

So the memhandler for that entry must be null.



Any reason this would be OK on the f23 build but not f24? Newer version of
gcc with different default behavior?


No idea, sorry.


Also, since that's pretty much greek to me, do you have a suggested fix?


Nope, I didn't look any further.
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Re: freecad: Need help with segfault problem on F24

[Richard Shaw]

Looks like Mamoru figured it out, thanks everyone for the help.

https://bugzilla.redhat.com/show_bug.cgi?id=1323159#c34

Thanks,
Richard
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Re: freecad: Need help with segfault problem on F24

[Richard Shaw]

On Fri, Apr 22, 2016 at 5:46 AM, Jonathan Wakely 
wrote:

> On 21/04/16 08:00 -0500, Richard Shaw wrote:
>
>> Well it turns out -fsanitize=undefined made no difference in this case...
>>
>> Here's the stacktrace:
>>
>> http://paste.fedoraproject.org/358119/46124321/
>>
>
> allocator=0x0 is the problem there, that argument must be non-null.
>
> It comes from:
>
>void operator delete(void * ptr) {
>  SbHashEntry * entry = static_cast( ptr);
>  cc_memalloc_deallocate(entry->memhandler, ptr);
>}
>
> So the memhandler for that entry must be null.


Any reason this would be OK on the f23 build but not f24? Newer version of
gcc with different default behavior?

Also, since that's pretty much greek to me, do you have a suggested fix?

Thanks,
Richard
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Re: freecad: Need help with segfault problem on F24

[Jonathan Wakely]

On 21/04/16 08:00 -0500, Richard Shaw wrote:

Well it turns out -fsanitize=undefined made no difference in this case...

Here's the stacktrace:

http://paste.fedoraproject.org/358119/46124321/


allocator=0x0 is the problem there, that argument must be non-null.

It comes from:

   void operator delete(void * ptr) {
 SbHashEntry * entry = static_cast( ptr);
 cc_memalloc_deallocate(entry->memhandler, ptr);
   }

So the memhandler for that entry must be null.
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Re: freecad: Need help with segfault problem on F24

[Richard Shaw]

Well it turns out -fsanitize=undefined made no difference in this case...

Here's the stacktrace:

http://paste.fedoraproject.org/358119/46124321/

Thanks,
Richard
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Re: freecad: Need help with segfault problem on F24

[Jonathan Wakely]

On 20/04/16 09:51 -0400, Przemek Klosowski wrote:

On 04/19/2016 11:55 PM, Jerry James wrote:

On Tue, Apr 19, 2016 at 8:50 PM, Richard Shaw  wrote:

I'm pretty much stumped on a problem where freecad (really python-pivy)
segfaults on F24 but seems to run fine on F23 and I can't find any
substantive difference between any of the packages.

Strangely installing Coin3 from f23 on a f24 system seems to fix the
problem...

Try building Coin3 with -fno-delete-null-pointer-checks in the CFLAGS.
I've had to add that to several packages on F24 to fix mysterious
segfaults.
Yeah, but that means that we're just allowing silent null-pointer 
dereferencing. This can't be good: it probably just masks latent bugs: 
https://gcc.gnu.org/news/null.html


Yes, but if the choices are to have code that dereferences null and
appears to work, or code that dereferences null and crashes, then
using the option as a temporary workaround is useful. Also, if the
option stops the crashes then it confirms that null dereferences are
indeed the cause of the crashes, not some other problem. That can
help find the real problem.

Building with -fsanitize=undefined should find the place where the
null dereference happens, so it can be fixed.
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Re: freecad: Need help with segfault problem on F24

[Przemek Klosowski]

On 04/19/2016 11:55 PM, Jerry James wrote:

On Tue, Apr 19, 2016 at 8:50 PM, Richard Shaw  wrote:

I'm pretty much stumped on a problem where freecad (really python-pivy)
segfaults on F24 but seems to run fine on F23 and I can't find any
substantive difference between any of the packages.

Strangely installing Coin3 from f23 on a f24 system seems to fix the
problem...

Try building Coin3 with -fno-delete-null-pointer-checks in the CFLAGS.
I've had to add that to several packages on F24 to fix mysterious
segfaults.
Yeah, but that means that we're just allowing silent null-pointer 
dereferencing. This can't be good: it probably just masks latent bugs: 
https://gcc.gnu.org/news/null.html


I understand that in principle, a program that segfaults due lack of the 
null-pointer test must be doing the actual null pointer dereference 
first. We should test for that and log bugs against such codeor is 
it too much work for too little benefit? Is there a way to automate 
that, e.g. via abrt?


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Re: freecad: Need help with segfault problem on F24

[Jerry James]

On Tue, Apr 19, 2016 at 8:50 PM, Richard Shaw  wrote:
> I'm pretty much stumped on a problem where freecad (really python-pivy)
> segfaults on F24 but seems to run fine on F23 and I can't find any
> substantive difference between any of the packages.
>
> Strangely installing Coin3 from f23 on a f24 system seems to fix the
> problem...

Try building Coin3 with -fno-delete-null-pointer-checks in the CFLAGS.
I've had to add that to several packages on F24 to fix mysterious
segfaults.
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