From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934901AbaICWov (ORCPT ); Wed, 3 Sep 2014 18:44:51 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:46551 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934425AbaICW2j (ORCPT ); Wed, 3 Sep 2014 18:28:39 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Oleg Nesterov , Aleksei Besogonov , David Rientjes , Andrew Morton , Linus Torvalds Subject: [PATCH 3.16 125/125] vm_is_stack: use for_each_thread() rather then buggy while_each_thread() Date: Wed, 3 Sep 2014 15:08:02 -0700 Message-Id: <20140903220627.447813092@linuxfoundation.org> X-Mailer: git-send-email 2.1.0 In-Reply-To: <20140903220623.649748296@linuxfoundation.org> References: <20140903220623.649748296@linuxfoundation.org> User-Agent: quilt/0.63-1 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 3.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Oleg Nesterov commit 4449a51a7c281602d3a385044ab928322a122a02 upstream. Aleksei hit the soft lockup during reading /proc/PID/smaps. David investigated the problem and suggested the right fix. while_each_thread() is racy and should die, this patch updates vm_is_stack(). Signed-off-by: Oleg Nesterov Reported-by: Aleksei Besogonov Tested-by: Aleksei Besogonov Suggested-by: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/util.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) --- a/mm/util.c +++ b/mm/util.c @@ -277,17 +277,14 @@ pid_t vm_is_stack(struct task_struct *ta if (in_group) { struct task_struct *t; - rcu_read_lock(); - if (!pid_alive(task)) - goto done; - t = task; - do { + rcu_read_lock(); + for_each_thread(task, t) { if (vm_is_stack_for_task(t, vma)) { ret = t->pid; goto done; } - } while_each_thread(task, t); + } done: rcu_read_unlock(); }