Re: [PATCH] kprobes: Fix to delay the kprobes jump optimization

[Steven Rostedt]

On Thu, 18 Feb 2021 23:29:23 +0900
Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote:

> Commit 36dadef23fcc ("kprobes: Init kprobes in early_initcall")
> moved the kprobe setup in early_initcall(), which includes kprobe
> jump optimization.
> The kprobes jump optimizer involves synchronize_rcu_tasks() which
> depends on the ksoftirqd and rcu_spawn_tasks_*(). However, since
> those are setup in core_initcall(), kprobes jump optimizer can not
> run at the early_initcall().
> 
> To avoid this issue, make the kprobe optimization disabled in the
> early_initcall() and enables it in subsys_initcall().
> 
> Note that non-optimized kprobes is still available after
> early_initcall(). Only jump optimization is delayed.
> 
> Fixes: 36dadef23fcc ("kprobes: Init kprobes in early_initcall")
> Reported-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
> Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
>

I pulled this into my queue to be tested, and when that completes
(hopefully without failure), I'll add this to my pull request for the
current merge window (which I still need to send).

Thanks!

-- Steve