linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: "Paul E. McKenney" <paulmck@kernel.org>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Uladzislau Rezki <urezki@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>, RCU <rcu@vger.kernel.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Andrew Morton <akpm@linux-foundation.org>,
	Daniel Axtens <dja@axtens.net>,
	Frederic Weisbecker <frederic@kernel.org>,
	Neeraj Upadhyay <neeraju@codeaurora.org>,
	Joel Fernandes <joel@joelfernandes.org>,
	Michal Hocko <mhocko@suse.com>,
	"Theodore Y . Ts'o" <tytso@mit.edu>,
	Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>
Subject: Re: [PATCH] kprobes: Fix to delay the kprobes jump optimization
Date: Thu, 18 Feb 2021 07:15:54 -0800	[thread overview]
Message-ID: <20210218151554.GQ2743@paulmck-ThinkPad-P72> (raw)
In-Reply-To: <161365856280.719838.12423085451287256713.stgit@devnote2>

On Thu, Feb 18, 2021 at 11:29:23PM +0900, Masami Hiramatsu 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@kernel.org>

Thank you, but the original report of a problem was from Sebastian
and the connection to softirq was Uladzislau.  So could you please
add these before (or even in place of) my Reported-by?

Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reported-by: Uladzislau Rezki <urezki@gmail.com>

Other than that, looks good!

Acked-by: Paul E. McKenney <paulmck@kernel.org>

							Thanx, Paul

> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> Cc: stable@vger.kernel.org
> ---
>  kernel/kprobes.c |   31 +++++++++++++++++++++----------
>  1 file changed, 21 insertions(+), 10 deletions(-)
> 
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index d5a3eb74a657..779d8322e307 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -861,7 +861,6 @@ static void try_to_optimize_kprobe(struct kprobe *p)
>  	cpus_read_unlock();
>  }
>  
> -#ifdef CONFIG_SYSCTL
>  static void optimize_all_kprobes(void)
>  {
>  	struct hlist_head *head;
> @@ -887,6 +886,7 @@ static void optimize_all_kprobes(void)
>  	mutex_unlock(&kprobe_mutex);
>  }
>  
> +#ifdef CONFIG_SYSCTL
>  static void unoptimize_all_kprobes(void)
>  {
>  	struct hlist_head *head;
> @@ -2497,18 +2497,14 @@ static int __init init_kprobes(void)
>  		}
>  	}
>  
> -#if defined(CONFIG_OPTPROBES)
> -#if defined(__ARCH_WANT_KPROBES_INSN_SLOT)
> -	/* Init kprobe_optinsn_slots */
> -	kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
> -#endif
> -	/* By default, kprobes can be optimized */
> -	kprobes_allow_optimization = true;
> -#endif
> -
>  	/* By default, kprobes are armed */
>  	kprobes_all_disarmed = false;
>  
> +#if defined(CONFIG_OPTPROBES) && defined(__ARCH_WANT_KPROBES_INSN_SLOT)
> +	/* Init kprobe_optinsn_slots for allocation */
> +	kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
> +#endif
> +
>  	err = arch_init_kprobes();
>  	if (!err)
>  		err = register_die_notifier(&kprobe_exceptions_nb);
> @@ -2523,6 +2519,21 @@ static int __init init_kprobes(void)
>  }
>  early_initcall(init_kprobes);
>  
> +#if defined(CONFIG_OPTPROBES)
> +static int __init init_optprobes(void)
> +{
> +	/*
> +	 * Enable kprobe optimization - this kicks the optimizer which
> +	 * depends on synchronize_rcu_tasks() and ksoftirqd, that is
> +	 * not spawned in early initcall. So delay the optimization.
> +	 */
> +	optimize_all_kprobes();
> +
> +	return 0;
> +}
> +subsys_initcall(init_optprobes);
> +#endif
> +
>  #ifdef CONFIG_DEBUG_FS
>  static void report_probe(struct seq_file *pi, struct kprobe *p,
>  		const char *sym, int offset, char *modname, struct kprobe *pp)
> 

  reply	other threads:[~2021-02-18 17:58 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-18 14:29 [PATCH] kprobes: Fix to delay the kprobes jump optimization Masami Hiramatsu
2021-02-18 15:15 ` Paul E. McKenney [this message]
2021-02-19  8:17   ` Sebastian Andrzej Siewior
2021-02-19 10:49     ` Uladzislau Rezki
2021-02-19 10:57       ` Sebastian Andrzej Siewior
2021-02-19 11:13         ` Uladzislau Rezki
2021-02-19 11:17           ` Sebastian Andrzej Siewior
2021-02-19 11:23             ` Uladzislau Rezki
2021-02-19 11:27               ` Uladzislau Rezki
2021-02-19 18:18                 ` Paul E. McKenney
2021-02-19 18:33                   ` Paul E. McKenney
2021-02-19 19:34                     ` Paul E. McKenney
2021-02-19 20:02                     ` Steven Rostedt
2021-02-19 21:22                       ` Paul E. McKenney
2021-02-22 10:21                     ` Sebastian Andrzej Siewior
2021-02-22 12:54                       ` Uladzislau Rezki
2021-02-22 15:09                         ` Paul E. McKenney
2021-02-22 17:16                           ` Uladzislau Rezki
2021-02-22 18:16                             ` Paul E. McKenney
2021-02-22 19:07                               ` Uladzislau Rezki
2021-02-22 21:32                                 ` Paul E. McKenney
2021-02-19 19:14                   ` Steven Rostedt
2021-02-19 19:45                     ` Paul E. McKenney
2021-02-19 20:04                       ` Paul E. McKenney
2021-02-22 10:04                   ` Sebastian Andrzej Siewior
2021-02-19 19:36 ` Steven Rostedt
2021-02-19 19:47   ` Paul E. McKenney
2021-02-19 19:58     ` Steven Rostedt
2021-02-19 20:04       ` Paul E. McKenney
2021-02-22 12:06         ` Masami Hiramatsu

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210218151554.GQ2743@paulmck-ThinkPad-P72 \
    --to=paulmck@kernel.org \
    --cc=akpm@linux-foundation.org \
    --cc=bigeasy@linutronix.de \
    --cc=dja@axtens.net \
    --cc=frederic@kernel.org \
    --cc=joel@joelfernandes.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mhiramat@kernel.org \
    --cc=mhocko@suse.com \
    --cc=mingo@kernel.org \
    --cc=mpe@ellerman.id.au \
    --cc=neeraju@codeaurora.org \
    --cc=oleksiy.avramchenko@sonymobile.com \
    --cc=peterz@infradead.org \
    --cc=rcu@vger.kernel.org \
    --cc=rostedt@goodmis.org \
    --cc=tglx@linutronix.de \
    --cc=tytso@mit.edu \
    --cc=urezki@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).