From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755992AbYHNURo (ORCPT ); Thu, 14 Aug 2008 16:17:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752883AbYHNURg (ORCPT ); Thu, 14 Aug 2008 16:17:36 -0400 Received: from smtp.wellnetcz.com ([212.24.148.102]:37127 "EHLO smtp.wellnetcz.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752394AbYHNURf (ORCPT ); Thu, 14 Aug 2008 16:17:35 -0400 From: Jiri Slaby To: Andrew Morton Cc: containers@lists.linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Jiri Slaby , Balbir Singh Subject: [PATCH 1/1] mm_owner: fix cgroup null dereference Date: Thu, 14 Aug 2008 22:16:53 +0200 Message-Id: <1218745013-9537-1-git-send-email-jirislaby@gmail.com> X-Mailer: git-send-email 1.5.6.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, found this in mmotm, a fix for mm-owner-fix-race-between-swap-and-exit.patch -- mm->owner is set to NULL prior to calling cgroup_mm_owner_callbacks, but it should be set after that to not pass NULL pointer as the old owner which otherwise results in an oops (shortened): BUG: unable to handle kernel NULL pointer dereference at 0000000000000580 Oops: 0000 [1] SMP Pid: 3396, comm: nscd Tainted: G W 2.6.27-rc3-mm1_64 #439 RIP: 0010:[] [] cgroup_mm_owner_callbacks+0x3a/0x90 RAX: 0000000000000000 RBX: ffffffff80589720 RCX: ffff880079f503e8 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff806c36e0 RBP: ffff880078291bd8 R08: ffff880078290000 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: ffff8800787f8e20 Call Trace: [] mm_update_next_owner+0x1ca/0x240 [] exit_mm+0x10a/0x150 [] do_exit+0x1dc/0x940 Code: 89 fe 41 55 49 89 f5 41 54 53 74 68 48 c7 c3 20 97 58 80 45 31 e4 0f 1f 00 48 8b 3b 4d 85 ed 48 63 47 58 48 8d 14 c5 00 00 00 00 <49> 8b 86 80 05 00 00 48 8d 44 10 38 48 8b 00 48 8b 30 74 12 49 Signed-off-by: Jiri Slaby Cc: Balbir Singh --- kernel/exit.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/kernel/exit.c b/kernel/exit.c index 3f47470..3a2a42a 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -637,8 +637,8 @@ retry: * the callback and take action */ down_write(&mm->mmap_sem); - mm->owner = NULL; cgroup_mm_owner_callbacks(mm->owner, NULL); + mm->owner = NULL; up_write(&mm->mmap_sem); return; -- 1.5.6.5