Re: [PATCH v3 3/5] slab: handle ERR_PTR values in kfree and hardened usercopy

[Karl Mehltretter]

> > +	if (WARN_ON(IS_ERR(object)))
> 
> Wonder if WARN_ON_ONCE() would be better.
> Also wonder about the benefits for hardening (as opposed to debugging).
> Without this check it would fault. Now it warns, but hardened setups often
> use panic_on_warn anyway, so the result is the same?
> 

Yes, I'll switch to WARN_ON_ONCE().

You're right about panic_on_warn. The benefit is a clearer diagnostic
and, when warnings aren't fatal, returning before virt_to_page().

I'll split out the ERR_PTR patches as Harry suggested and recheck the
KUnit warning-count test with WARN_ON_ONCE().

Thanks,
Karl