From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1164394AbeE1Kz1 (ORCPT ); Mon, 28 May 2018 06:55:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:43990 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1164369AbeE1KzX (ORCPT ); Mon, 28 May 2018 06:55:23 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Steven J. Hill" , Andrew Morton , Tejun Heo , Linus Torvalds , Sasha Levin Subject: [PATCH 4.14 310/496] mm/vmstat.c: fix vmstat_update() preemption BUG Date: Mon, 28 May 2018 12:01:35 +0200 Message-Id: <20180528100332.859289706@linuxfoundation.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180528100319.498712256@linuxfoundation.org> References: <20180528100319.498712256@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: "Steven J. Hill" [ Upstream commit c7f26ccfb2c31eb1bf810ba13d044fcf583232db ] Attempting to hotplug CPUs with CONFIG_VM_EVENT_COUNTERS enabled can cause vmstat_update() to report a BUG due to preemption not being disabled around smp_processor_id(). Discovered on Ubiquiti EdgeRouter Pro with Cavium Octeon II processor. BUG: using smp_processor_id() in preemptible [00000000] code: kworker/1:1/269 caller is vmstat_update+0x50/0xa0 CPU: 0 PID: 269 Comm: kworker/1:1 Not tainted 4.16.0-rc4-Cavium-Octeon-00009-gf83bbd5-dirty #1 Workqueue: mm_percpu_wq vmstat_update Call Trace: show_stack+0x94/0x128 dump_stack+0xa4/0xe0 check_preemption_disabled+0x118/0x120 vmstat_update+0x50/0xa0 process_one_work+0x144/0x348 worker_thread+0x150/0x4b8 kthread+0x110/0x140 ret_from_kernel_thread+0x14/0x1c Link: http://lkml.kernel.org/r/1520881552-25659-1-git-send-email-steven.hill@cavium.com Signed-off-by: Steven J. Hill Reviewed-by: Andrew Morton Cc: Tejun Heo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- mm/vmstat.c | 2 ++ 1 file changed, 2 insertions(+) --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -1770,9 +1770,11 @@ static void vmstat_update(struct work_st * to occur in the future. Keep on running the * update worker thread. */ + preempt_disable(); queue_delayed_work_on(smp_processor_id(), mm_percpu_wq, this_cpu_ptr(&vmstat_work), round_jiffies_relative(sysctl_stat_interval)); + preempt_enable(); } }