Re: [PATCH v3 1/7] Fix "x86/alternatives: Lockdep-enforce text_mutex in text_poke*()"

[Jiri Kosina]

On Fri, 2 Nov 2018, 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.
> 
> Add a comment to clarify this behavior, and restore the assertions as
> they were before the recent commit.
> 
> This partially reverts commit 9222f606506c ("x86/alternatives:
> Lockdep-enforce text_mutex in text_poke*()")

Alright, what can we do. It's probably better to have this, rather than to 
trying to work this around in kgdb to accomodate the rest of the world.

> Cc: Jiri Kosina <jkosina@xxxxxxx>
> Cc: Andy Lutomirski <luto@xxxxxxxxxx>
> Cc: Kees Cook <keescook@xxxxxxxxxxxx>
> Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
> Fixes: 9222f606506c ("x86/alternatives: Lockdep-enforce text_mutex in text_poke*()")
> Reviewed-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> Tested-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> Suggested-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Signed-off-by: Nadav Amit <namit@xxxxxxxxxx>

Acked-by: Jiri Kosina <jkosina@xxxxxxx>

Thanks,

-- 
Jiri Kosina
SUSE Labs