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

[Nadav Amit]

at 1:25 PM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:

> On Thu, Sep 06, 2018 at 07:58:40PM +0000, Nadav Amit wrote:
>>> With that CR3 trickery, we can rid ourselves of the text_mutex
>>> requirement, since concurrent text_poke is 'safe'. That would clean up
>>> the kgdb code quite a bit.
>> 
>> I donât know. Iâm somewhat worried with multiple mechanisms potentially
>> changing the same code at the same time - and maybe ending up with some
>> mess.
> 
> kgdb only pokes INT3, that should be pretty safe.

Maybe I misunderstand your point. If you want me to get rid of text_mutex
completely, I am afraid it will be able to cause mess by changing the same
piece of code through kprobes and the static-keys mechanism.

I doubt it would work today without failing, but getting rid of text_mutex
is likely to make it even worse.