Re: [PATCH v2 1/6] Fix "x86/alternatives: Lockdep-enforce text_mutex in text_poke*()"

[Peter Zijlstra]

On Sun, Sep 02, 2018 at 10:32:19AM -0700, Nadav Amit wrote:
> text_mutex is expected to be held before text_poke() is called, but we
> cannot add a lockdep assertion since kgdb does not take it, and instead
> *supposedly* ensures the lock is not taken and will not be acquired by
> any other core while text_poke() is running.
> 
> The reason for the "supposedly" comment is that it is not entirely clear
> that this would be the case if gdb_do_roundup is zero.

Argh, that's pretty shit code...

Not only is that text_mutex abuse ugly, so too is the fixmap usage from
IRQ context. I suppose this really does require your alternative mm
patches for text_poke().