From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933074AbaIOWTR (ORCPT ); Mon, 15 Sep 2014 18:19:17 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:51148 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933056AbaIOWTM (ORCPT ); Mon, 15 Sep 2014 18:19:12 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Oleg Nesterov , Andrew Morton , Linus Torvalds , Kamal Mostafa Subject: [PATCH 3.13 171/187] vm_is_stack: use for_each_thread() rather then buggy while_each_thread() Date: Mon, 15 Sep 2014 15:09:41 -0700 Message-Id: <1410818997-9432-172-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1410818997-9432-1-git-send-email-kamal@canonical.com> References: <1410818997-9432-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.13 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.13.11.7 -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: Kamal Mostafa --- mm/util.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/mm/util.c b/mm/util.c index 8636d3d..89abc97 100644 --- a/mm/util.c +++ b/mm/util.c @@ -276,17 +276,14 @@ pid_t vm_is_stack(struct task_struct *task, 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(); } -- 1.9.1