RE: [PATCH 2/2] futex, x86/mce: Avoid double machine checks

[Luck, Tony]

> I think this is horrid; why can't we have it return something different
> then -EFAULT instead?

I did consider this ... but it appears that architectures aren't unified in the
return value from get_user()

Here's another function involved in the futex call chain leading to this:

static int get_futex_value_locked(u32 *dest, u32 __user *from)
{
        int ret;

        pagefault_disable();
        ret = __get_user(*dest, from);
        pagefault_enable();

        return ret ? -EFAULT : 0;
}

It seems like the expectation here is just "zero or not" and we
don't care what the "not" value is ... just turn it into -EFAULT.

-Tony