From: Christoph Hellwig Subject: Re: [PATCH] Check for error returned by kthread_create on creating journal thread Date: Mon, 16 Apr 2007 11:21:07 +0100 Message-ID: <20070416102107.GA12818@infradead.org> References: <4623289A.1000101@sw.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: sct@redhat.com, akpm@linux-foundation.org, linux-ext4@vger.kernel.org, Linux Kernel Mailing List , devel@openvz.org To: Pavel Emelianov Return-path: Received: from pentafluge.infradead.org ([213.146.154.40]:41546 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751648AbXDPKVW (ORCPT ); Mon, 16 Apr 2007 06:21:22 -0400 Content-Disposition: inline In-Reply-To: <4623289A.1000101@sw.ru> Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Mon, Apr 16, 2007 at 11:41:14AM +0400, Pavel Emelianov wrote: > If the thread failed to create the subsequent wait_event > will hang forever. > > This is likely to happen if kernel hits max_threads limit. > > Will be critical for virtualization systems that limit the > number of tasks and kernel memory usage within the container. > --- ./fs/jbd/journal.c.jbdthreads 2007-04-16 11:17:36.000000000 +0400 > +++ ./fs/jbd/journal.c 2007-04-16 11:30:09.000000000 +0400 > @@ -211,10 +211,16 @@ end_loop: > return 0; > } > > -static void journal_start_thread(journal_t *journal) > +static int journal_start_thread(journal_t *journal) > { > - kthread_run(kjournald, journal, "kjournald"); > + struct task_struct *t; > + > + t = kthread_run(kjournald, journal, "kjournald"); > + if (IS_ERR(t)) > + return PTR_ERR(t); > + > wait_event(journal->j_wait_done_commit, journal->j_task != 0); Note that this wait_event should exist at all, and the return value of kthread_run should be assigned to journal->j_task. Also the code doesn't use the kthread primitives in other places leading to crufty code.