From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932868AbbCQRLW (ORCPT ); Tue, 17 Mar 2015 13:11:22 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51520 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754305AbbCQRLU (ORCPT ); Tue, 17 Mar 2015 13:11:20 -0400 Date: Tue, 17 Mar 2015 18:09:20 +0100 From: Oleg Nesterov To: Aaron Tomlin Cc: akpm@linux-foundation.org, rientjes@google.com, dwysocha@redhat.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] hung_task: Change hung_task.c to use for_each_process_thread() Message-ID: <20150317170920.GA21493@redhat.com> References: <1426601624-6703-1-git-send-email-atomlin@redhat.com> <1426601624-6703-2-git-send-email-atomlin@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1426601624-6703-2-git-send-email-atomlin@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 On 03/17, Aaron Tomlin wrote: > > --- a/kernel/hung_task.c > +++ b/kernel/hung_task.c > @@ -169,7 +169,7 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout) > return; > > rcu_read_lock(); > - do_each_thread(g, t) { > + for_each_process_thread(g, t) { > if (!max_count--) > goto unlock; > if (!--batch_count) { > @@ -180,7 +180,7 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout) > /* use "==" to skip the TASK_KILLABLE tasks waiting on NFS */ > if (t->state == TASK_UNINTERRUPTIBLE) > check_hung_task(t, timeout); > - } while_each_thread(g, t); > + } Acked-by: Oleg Nesterov Perhaps it also makes sense to improve this rcu_lock_break a bit... For example, if 't' is dead but 'g' is alive we can continue the "for_each_process" part of this double loop. And if 't' is still alive then we can find the new leader and continue... But I agree, lets start from this fix, then we will see. Oleg.