From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Rostedt Subject: [PATCH RT 2/4] fs: jbd2: pull your plug when waiting for space Date: Thu, 13 Mar 2014 06:44:16 -0400 Message-ID: <20140313104428.938228701@goodmis.org> References: <20140313104414.588331401@goodmis.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: Thomas Gleixner , Carsten Emde , Sebastian Andrzej Siewior , John Kacur , Paul Gortmaker , To: linux-kernel@vger.kernel.org, linux-rt-users Return-path: Content-Disposition: inline; filename=0002-fs-jbd2-pull-your-plug-when-waiting-for-space.patch Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-rt-users.vger.kernel.org 3.4.82-rt103-rc1 stable review patch. If anyone has any objections, please let me know. ------------------ From: Sebastian Andrzej Siewior Two cps in parallel managed to stall the the ext4 fs. It seems that journal code is either waiting for locks or sleeping waiting for something to happen. This seems similar to what Mike observed on ext3, here is his description: |With an -rt kernel, and a heavy sync IO load, tasks can jam |up on journal locks without unplugging, which can lead to |terminal IO starvation. Unplug and schedule when waiting |for space. Cc: stable-rt@vger.kernel.org Signed-off-by: Sebastian Andrzej Siewior --- fs/jbd2/checkpoint.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c index c78841e..a4d273b 100644 --- a/fs/jbd2/checkpoint.c +++ b/fs/jbd2/checkpoint.c @@ -125,6 +125,8 @@ void __jbd2_log_wait_for_space(journal_t *journal) if (journal->j_flags & JBD2_ABORT) return; write_unlock(&journal->j_state_lock); + if (current->plug) + io_schedule(); mutex_lock(&journal->j_checkpoint_mutex); /* -- 1.8.5.3