From patchwork Tue Jan 2 03:40:24 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chen Zhongjin X-Patchwork-Id: 13508793 Received: from szxga04-in.huawei.com (szxga04-in.huawei.com [45.249.212.190]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4E62AEBF; Tue, 2 Jan 2024 03:43:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.163.44]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4T3zDl56V5z29jK8; Tue, 2 Jan 2024 11:41:59 +0800 (CST) Received: from dggpemd100005.china.huawei.com (unknown [7.185.36.102]) by mail.maildlp.com (Postfix) with ESMTPS id 6737E140135; Tue, 2 Jan 2024 11:43:24 +0800 (CST) Received: from hulk-vt.huawei.com (10.67.174.104) by dggpemd100005.china.huawei.com (7.185.36.102) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.2.1258.28; Tue, 2 Jan 2024 11:43:24 +0800 From: Chen Zhongjin To: , CC: , , , , , , , , , , , , , , , , Subject: [RFC PATCH] kprobes: Use synchronize_rcu_tasks_rude in kprobe_optimizer Date: Tue, 2 Jan 2024 03:40:24 +0000 Message-ID: <20240102034024.256326-1-chenzhongjin@huawei.com> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpemd100005.china.huawei.com (7.185.36.102) There is a deadlock scenario in kprobe_optimizer(): pid A pid B pid C kprobe_optimizer() do_exit() perf_kprobe_init() mutex_lock(&kprobe_mutex) exit_tasks_rcu_start() mutex_lock(&kprobe_mutex) synchronize_rcu_tasks() zap_pid_ns_processes() // waiting kprobe_mutex // waiting tasks_rcu_exit_srcu kernel_wait4() // waiting pid C exit To avoid this deadlock loop, use synchronize_rcu_tasks_rude() in kprobe_optimizer() rather than synchronize_rcu_tasks(). synchronize_rcu_tasks_rude() can also promise that all preempted tasks have scheduled, but it will not wait tasks_rcu_exit_srcu. Signed-off-by: Chen Zhongjin Tested-by: Yang Jihong Tested-by: Yang Jihong --- arch/Kconfig | 2 +- kernel/kprobes.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/Kconfig b/arch/Kconfig index f4b210ab0612..dc6a18854017 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -104,7 +104,7 @@ config STATIC_CALL_SELFTEST config OPTPROBES def_bool y depends on KPROBES && HAVE_OPTPROBES - select TASKS_RCU if PREEMPTION + select TASKS_RUDE_RCU config KPROBES_ON_FTRACE def_bool y diff --git a/kernel/kprobes.c b/kernel/kprobes.c index d5a0ee40bf66..09056ae50c58 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -623,7 +623,7 @@ static void kprobe_optimizer(struct work_struct *work) * Note that on non-preemptive kernel, this is transparently converted * to synchronoze_sched() to wait for all interrupts to have completed. */ - synchronize_rcu_tasks(); + synchronize_rcu_tasks_rude(); /* Step 3: Optimize kprobes after quiesence period */ do_optimize_kprobes();