From: Pavel Emelianov Subject: [PATCH] Check for error returned by kthread_create on creating journal thread Date: Mon, 16 Apr 2007 11:41:14 +0400 Message-ID: <4623289A.1000101@sw.ru> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="------------020900000406050409030808" Cc: Linux Kernel Mailing List , devel@openvz.org To: sct@redhat.com, akpm@linux-foundation.org, linux-ext4@vger.kernel.org Return-path: Received: from mailhub.sw.ru ([195.214.233.200]:11417 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753072AbXDPHg5 (ORCPT ); Mon, 16 Apr 2007 03:36:57 -0400 Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org This is a multi-part message in MIME format. --------------020900000406050409030808 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit 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. --------------020900000406050409030808 Content-Type: text/plain; name="diff-jbd-check-start-journal-thread-return-value" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="diff-jbd-check-start-journal-thread-return-value" --- ./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); + return 0; } static void journal_kill_thread(journal_t *journal) @@ -840,8 +846,7 @@ static int journal_reset(journal_t *jour /* Add the dynamic fields and write it to disk. */ journal_update_superblock(journal, 1); - journal_start_thread(journal); - return 0; + return journal_start_thread(journal); } /** --- ./fs/jbd2/journal.c.jbdthreads 2007-04-16 11:17:36.000000000 +0400 +++ ./fs/jbd2/journal.c 2007-04-16 11:27:45.000000000 +0400 @@ -211,10 +211,16 @@ end_loop: return 0; } -static void jbd2_journal_start_thread(journal_t *journal) +static int jbd2_journal_start_thread(journal_t *journal) { - kthread_run(kjournald2, journal, "kjournald2"); + struct task_struct *t; + + t = kthread_run(kjournald2, journal, "kjournald2"); + if (IS_ERR(t)) + return PTR_ERR(t); + wait_event(journal->j_wait_done_commit, journal->j_task != 0); + return 0; } static void journal_kill_thread(journal_t *journal) @@ -840,8 +846,7 @@ static int journal_reset(journal_t *jour /* Add the dynamic fields and write it to disk. */ jbd2_journal_update_superblock(journal, 1); - jbd2_journal_start_thread(journal); - return 0; + return jbd2_journal_start_thread(journal); } /** --------------020900000406050409030808--