linux-kernel - Re: [RFC PATCH -tip 8/9] error-injection: Fix to not enabling preemption in pre

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Date:   Sat, 10 Mar 2018 09:22:48 +0100
From:   Ingo Molnar <mingo@...nel.org>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
        Yang Bo <yangbo@...pin.com>, Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
        Ananth N Mavinakayanahalli <ananth@...ux.vnet.ibm.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Laura Abbott <labbott@...hat.com>, Josef Bacik <jbacik@...com>,
        Alexei Starovoitov <ast@...nel.org>
Subject: Re: [RFC PATCH -tip 8/9] error-injection: Fix to not enabling
 preemption in pre_handler


* Masami Hiramatsu <mhiramat@...nel.org> wrote:

> Since kprobes pre_handler doesn't need to recover preemption
> even if it modifies regs->ip anymore, this fixes to remove
> the preempt_enable_no_resched() from pre_handler.
> 
> Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
> ---
>  kernel/fail_function.c |    1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/kernel/fail_function.c b/kernel/fail_function.c
> index 21b0122cb39c..b1713521f096 100644
> --- a/kernel/fail_function.c
> +++ b/kernel/fail_function.c
> @@ -176,7 +176,6 @@ static int fei_kprobe_handler(struct kprobe *kp, struct pt_regs *regs)
>  		override_function_with_return(regs);
>  		/* Kprobe specific fixup */
>  		reset_current_kprobe();
> -		preempt_enable_no_resched();
>  		return 1;
>  	}

So where did the matching preempt_disable() get removed? If it's the 6/9 patch, 
then this patch (and 8/9) should very much be part of it.

There should be no bisection breakage in the series.

Thanks,

	Ingo