RES: Facing GC infinite loop in Lua 5.1

[Wagner Fernando Fazio <wagner.fazio@...>]

You are absolutely right!!! There was a memory corruption caused by sprintf misuse. 

Thank you a lot for spending your time.

It was  5.1.4 version with some extensions



-----Mensagem original-----
De: nerditation <nerditation@outlook.com> 
Enviada em: quarta-feira, 3 de fevereiro de 2021 12:51
Para: lua-l@lists.lua.org
Assunto: Re: Facing GC infinite loop in Lua 5.1

On 2021/1/28 2:15, Wagner Fernando Fazio wrote:
> I'm looping forever when calling luaC_fullgc and can not realize why it is happening. Every call do singlestep() does nothing and sweeplist() keeps trying to mark objects as white in every call.
> 
>  
> 
> At this moment, my debugger shows deadmask==33(0x21) and all are gch.marked==2.
> 
>  
> 
> Can someone figure out situations where it may happen?
> 
> [...]


do you use a patched Lua or official release version? which exact version of Lua do you use?
or do you have a custom memory allocator?

if the gc got stuck in the sweep phase, I can only imagine there exists a cycle in the `allgc` list, which should be a singly linked list through the `gch->next` field in every gc object.

so I suspect your allocator might caused a memory corruption and overwritten the `gch->next` field of some gc objects, which happened to point to some other objects, thus making the `allgc` list `infinitely` long.

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