Re: crash in entry.S restore_all, 2.6.12-rc2, x86, PAGEALLOC

Linus Torvalds
2005-04-07T16:53:38Z

On Thu, 7 Apr 2005, Stas Sergeev wrote:
>
> 1. Does the "later sti" fixes the problem
> also in case of an NMI? I mean, why can't
> you just be NMI'ed before you did sti?
> NMI uses the restore_all too IIRC.

The NMI code had better be really careful, and yeah, I suspect it needs
fixing.

> 2. How can one be sure there are no more
> of the like places where the stack is left
> empty?

That's a good argument, and may be the strongest reason for _not_ doing
the speculation. However, I don't think it really can happen anywhere
else.

If people feel very nervous about the speculation, we can certainly just
make it do the two branches. It _is_ a hotspot, though, and the
optimization of the speculatiom may well be worth it.

Linus