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

From: Ingo Molnar <mingo@kernel.org>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	x86@kernel.org, Yang Bo <yangbo@deepin.com>,
	Ingo Molnar <mingo@redhat.com>, "H . Peter Anvin" <hpa@zytor.com>,
	linux-kernel@vger.kernel.org,
	Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Laura Abbott <labbott@redhat.com>, Josef Bacik <jbacik@fb.com>,
	Alexei Starovoitov <ast@kernel.org>
Subject: Re: [RFC PATCH -tip 8/9] error-injection: Fix to not enabling preemption in pre_handler
Date: Sat, 10 Mar 2018 09:22:48 +0100	[thread overview]
Message-ID: <20180310082248.6inyi5rcxhay2e6v@gmail.com> (raw)
In-Reply-To: <152059915597.4214.4086303893931787678.stgit@devbox>

* Masami Hiramatsu <mhiramat@kernel.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@kernel.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