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Re: pg_jobc going negative?



On 09.06.2020 10:23, Michael van Elst wrote:
> max%m00nbsd.net@localhost (Maxime Villard) writes:
> 
>> You can see they are all different, but all have to do with reading the
>> group pointer, which was either freed, overwritten, not initialized,
>> unmapped, or contained pure garbage. This is typical of refcounting bugs
>> where a resource disappears under your feet.
> 
> pg_jobc is not a reference counter. The assertion probably stopped
> a bug in a different place by coincidence.
> 

As the first step, is it fine to replace all pg_jobc == 0/ != 0 checks
with pg_jobc > 0 / <= 0?

This should not make anything worse than it is now.

The remaining code assumes that pg_jobc never goes below 0.

And then, follow up with the removal of the assert. We will check with
syzkaller whether the races/crashes are gone.

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