From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0FD0EC433E6 for ; Thu, 18 Feb 2021 17:58:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C902D64E2E for ; Thu, 18 Feb 2021 17:58:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230290AbhBRR6b (ORCPT ); Thu, 18 Feb 2021 12:58:31 -0500 Received: from mail.kernel.org ([198.145.29.99]:43222 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230299AbhBRPQh (ORCPT ); Thu, 18 Feb 2021 10:16:37 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id A82F664E33; Thu, 18 Feb 2021 15:15:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1613661354; bh=MyfFbfr3pNGHW7aF5apPLt2vI7LPbZ/mH6iNBNniVm4=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=ojh8k9zXSMwDmKBSlWGCV6XfaPgE1sNCgdjMsXcouq6f3dx7eQlTVyGtQ+m60+PE1 HkZAvmAlTMgkMvkeXw5aymchPEHqRZE8/PQRCMt92hv4FNCQVPz5ZkLTFHd/ipcuwn oKMVvjKyDYrc1ZkKs5+hr7wjCK+KlLmnk3jJcGCqlVrYW9kfhSCzdVRMr0bA8kZ7SK inKJ/vVvGCW7ud346TKps/ticZn/uFlBjE6KnoVsiQnCjPf7Bq8AvvFEWzVjJLIpp9 lqRyzTnwnYhf8PMdWvsrYsYSTQt6S6M5DlWUKZz1rdBkJlbq0KGSEG4yIe7rJg2l1A TkZvFtzOmZ05g== Received: by paulmck-ThinkPad-P72.home (Postfix, from userid 1000) id 5E9C435226A0; Thu, 18 Feb 2021 07:15:54 -0800 (PST) Date: Thu, 18 Feb 2021 07:15:54 -0800 From: "Paul E. McKenney" To: Masami Hiramatsu Cc: Ingo Molnar , Steven Rostedt , Sebastian Andrzej Siewior , Peter Zijlstra , Thomas Gleixner , Uladzislau Rezki , LKML , RCU , Michael Ellerman , Andrew Morton , Daniel Axtens , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Michal Hocko , "Theodore Y . Ts'o" , Oleksiy Avramchenko Subject: Re: [PATCH] kprobes: Fix to delay the kprobes jump optimization Message-ID: <20210218151554.GQ2743@paulmck-ThinkPad-P72> Reply-To: paulmck@kernel.org References: <161365856280.719838.12423085451287256713.stgit@devnote2> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <161365856280.719838.12423085451287256713.stgit@devnote2> User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 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 Reported-by: Uladzislau Rezki Other than that, looks good! Acked-by: Paul E. McKenney Thanx, Paul > Signed-off-by: Masami Hiramatsu > 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) >