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)
>
next prev parent 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).