[Tarantool-patches] [PATCH v7 2/2] fiber: leak slab if unable to bring prots back
Cyrill Gorcunov
gorcunov at gmail.com
Fri Feb 14 11:25:18 MSK 2020
On Fri, Feb 14, 2020 at 12:26:04AM +0100, Vladislav Shpilevoy wrote:
> > --- a/test/unit/fiber_stack.c
> > +++ b/test/unit/fiber_stack.c
> > @@ -59,6 +58,30 @@ main_f(va_list ap)
> > ok(fiber != NULL, "madvise: non critical error on madvise hint");
> > ok(diag_get() != NULL, "madvise: diag is armed after error");
> >
> > + /*
> > + * Check if we leak on fiber descrution.
>
> 1. You probably have meant 'destruction'.
Sharp eyes =) Thanks!
> > +
> > + fiber_attr_delete(fiber_attr);
>
> 2. When I run the test without the fix, I got 'Bus error'.
> Was it intended? In my email I proposed to compare memory
Hmm. Actually not, should not be. I'll dig into, thanks!
> statistics, but crash also looks ok, maybe. If this is what
> you meant. And then there should be a comment saying, that we
> expect fiber_join() to crash when no leak is done, because it
> would put the slab into the cash, where it would be read/written
> against protection. This was not obvious until I reverted your
> patch and run the test.
I'll try to play with statistics again, the error message
was just simplier and faster.
> IMO, problem of that way of testing is that if internals of
> core/fiber.c one day will stop touching stack of a just
> destroyed fiber (for example, a pointer at it would be cached
> somewhere for newer fibers), this test will happily pass, even
> though it perhaps should not. It will pass regardless of what
> happens with a fiber stack unless something tries to read/write
> it.
Thanks for comments!
Cyrill
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