From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964853AbWFXVxx (ORCPT ); Sat, 24 Jun 2006 17:53:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964851AbWFXVxx (ORCPT ); Sat, 24 Jun 2006 17:53:53 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:36763 "EHLO mx2.mail.elte.hu") by vger.kernel.org with ESMTP id S964847AbWFXVxw (ORCPT ); Sat, 24 Jun 2006 17:53:52 -0400 Date: Sat, 24 Jun 2006 23:48:53 +0200 From: Ingo Molnar To: Andrew Morton Cc: Arjan van de Ven , linux-kernel@vger.kernel.org Subject: [patch, 2.6.17-mm2] fix acct_collect() siglock bug Message-ID: <20060624214853.GA19254@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4.2.1i X-ELTE-SpamScore: -3.1 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-3.1 required=5.9 tests=ALL_TRUSTED,AWL,BAYES_50 autolearn=no SpamAssassin version=3.0.3 -3.3 ALL_TRUSTED Did not pass through any untrusted hosts 0.0 BAYES_50 BODY: Bayesian spam probability is 40 to 60% [score: 0.5002] 0.2 AWL AWL: From: address is in the auto white-list X-ELTE-VirusStatus: clean Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org the patch below fixes a siglock usage bug introduced in -mm2. The lock validator found it during bootup. --------------- Subject: fix acct_collect() siglock bug From: Ingo Molnar the lock validator noticed the following bug: ========================================================= [ INFO: possible irq lock inversion dependency detected ] --------------------------------------------------------- swapper/0 just changed the state of lock: (tasklist_lock){..-?}, at: [] send_group_sig_info+0xe/0x2f but this lock took another, soft-irq-unsafe lock in the past: (&sighand->siglock){--..} and interrupts could create inverse lock ordering between them. ... -> (init_sighand.siglock){....} ops: 18 { ... hardirq-on-W at: [] lock_acquire+0x56/0x73 [] _spin_lock+0x24/0x32 [] acct_collect+0x81/0x115 [] do_exit+0x19a/0x7b3 [] ____call_usermodehelper+0xdf/0xe1 [] kernel_thread_helper+0x5/0xb it turns out that acct_collect() takes current->sighand->siglock with interrupts enabled - a big no-no. Fix it by disabling interrupts. Signed-off-by: Ingo Molnar --- kernel/acct.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) Index: linux/kernel/acct.c =================================================================== --- linux.orig/kernel/acct.c +++ linux/kernel/acct.c @@ -549,7 +549,7 @@ void acct_collect(long exitcode, int gro up_read(¤t->mm->mmap_sem); } - spin_lock(¤t->sighand->siglock); + spin_lock_irq(¤t->sighand->siglock); if (group_dead) pacct->ac_mem = vsize / 1024; if (thread_group_leader(current)) { @@ -567,7 +567,7 @@ void acct_collect(long exitcode, int gro pacct->ac_stime = cputime_add(pacct->ac_stime, current->stime); pacct->ac_minflt += current->min_flt; pacct->ac_majflt += current->maj_flt; - spin_unlock(¤t->sighand->siglock); + spin_unlock_irq(¤t->sighand->siglock); } /**