From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754838Ab2HZTKU (ORCPT ); Sun, 26 Aug 2012 15:10:20 -0400 Received: from mx1.redhat.com ([209.132.183.28]:13167 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753228Ab2HZTJt (ORCPT ); Sun, 26 Aug 2012 15:09:49 -0400 Date: Sun, 26 Aug 2012 21:12:14 +0200 From: Oleg Nesterov To: Peter Zijlstra , Al Viro Cc: Dave Jones , Linux Kernel , Thomas Gleixner , rostedt , dhowells , Linus Torvalds Subject: [PATCH 3/4] task_work: revert d35abdb2 "hold task_lock around checks in keyctl" Message-ID: <20120826191214.GA4231@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120826191132.GA3743@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This reverts commit d35abdb28824cf74f0a106a0f9c6f3ff700a35bf. task_lock() was added to ensure exit_mm() and thus exit_task_work() is not possible before task_work_add(). This is wrong, task_lock() must not be nested with write_lock(tasklist). And this is no longer needed, task_work_add() fails if it is called after exit_task_work(). Reported-by: Dave Jones Signed-off-by: Oleg Nesterov --- security/keys/keyctl.c | 2 -- 1 files changed, 0 insertions(+), 2 deletions(-) diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c index 3364fbf..6cfc647 100644 --- a/security/keys/keyctl.c +++ b/security/keys/keyctl.c @@ -1486,7 +1486,6 @@ long keyctl_session_to_parent(void) oldwork = NULL; parent = me->real_parent; - task_lock(parent); /* the parent mustn't be init and mustn't be a kernel thread */ if (parent->pid <= 1 || !parent->mm) goto unlock; @@ -1530,7 +1529,6 @@ long keyctl_session_to_parent(void) if (!ret) newwork = NULL; unlock: - task_unlock(parent); write_unlock_irq(&tasklist_lock); rcu_read_unlock(); if (oldwork) -- 1.5.5.1