[ODE] SIGSEGV in dSolveLCP() at ode/src/lcp.cpp:1137

[Olivier Michel]

Well, it works fine now. I patched the lcp.cpp file as follow:

#define ALLOCA(x) malloc(x)
#define FREEA(a) free(x)

and I added a FREEA() for each ALLOCA() call in the source code. Now my 
simulation never crashes (great!).
We could do the same for other files (step.cpp, matrix.cpp, etc.) and 
set up some #ifdef stuff so that the user can compile ODE in stack 
allocation of dynamic allocation mode.

I volunteer to implement this patch if it will be integrated into the 
main ODE CVS trunk.

Let me know what do you think about it.

-Olivier


Olivier Michel wrote:

> Thanks for the replies. However, I cannot work around this problem:
>
> (1) I tryed increasing the heap size under Linux: "ulimit -s 
> unlimited" to increase the heap size from 8192 to unlimited, but that 
> didn't helped (might be ineffective).
>
> (2) I tryed to use dWorldStepFast1 instead of dWorldStep, but then all 
> my bodies are falling down breaking the joints I set. I set all the 
> masses to 1 to try to avoid this problem but it didn't change anything 
> (still collapsing the model).
>
> It seems the simulation works with fine dSolveLCP() when the n 
> parameter remains below ~200. However, when my two humanoid robots hit 
> each other (~44 bodies connected through joints), n reaches 384 and 
> the SIGSEGV occurs...
>
> I will try to replace all the ALLOCA from lcp.cpp to dynamical 
> allocations / desallocations as it seems to be the only way to work 
> around this problem, isn't it ?
>
> If it works, may I contribute this alternative to the ODE cvs if this 
> is usefull for others ?
>
> -Olivier
>
> Martin C. Martin wrote:
>
>> Search the docs for "stack," and you'll see at least two things you 
>> can do.
>>
>> - Martin
>>
>> Olivier Michel wrote:
>>
>>> Hi there,
>>>
>>> I have a bug in my ODE simulation which occurs in ODE dSolveLCP() 
>>> function after a while and when two objects enter in collision, but 
>>> I don't understand why a SIGSEGV occurs while creating a stack 
>>> object in ode/src/lcp.cpp:1137. Here is what I get from gdb (under 
>>> Linux/woody):
>>>
>>> Program received signal SIGSEGV, Segmentation fault.
>>> [Switching to Thread 1024 (LWP 6180)]
>>> 0x0817333e in dSolveLCP (n=351, A=0xbfef1630, x=0xbfeef480, 
>>> b=0xbfeeff90,
>>>   w=0xbfeee970, nub=0, lo=0xbfff9af0, hi=0xbfff8fe0, findex=0xbfff8a54)
>>>   at ode/src/lcp.cpp:1137
>>> 1137      dLCP lcp 
>>> (n,nub,A,x,b,w,lo,hi,L,d,Dell,ell,delta_w,state,findex,p,C,Arows);
>>>
>>> How can the creation of a dLCP object cause a SIGSEGV ? Shall I try 
>>> to replace it by something like:
>>>
>>> dLCP *lcp = new dLCP(...);
>>>
>>> Any hint would be appreciated.
>>>
>>> -Olivier
>>
>>
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