Return-Path: Received: from mail-wm0-f68.google.com ([74.125.82.68]:33223 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755184AbdAFOLZ (ORCPT ); Fri, 6 Jan 2017 09:11:25 -0500 From: Michal Hocko To: , Cc: Andrew Morton , Dave Chinner , djwong@kernel.org, "Theodore Ts'o" , Chris Mason , David Sterba , Jan Kara , ceph-devel@vger.kernel.org, cluster-devel@redhat.com, linux-nfs@vger.kernel.org, logfs@logfs.org, linux-xfs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-mtd@lists.infradead.org, reiserfs-devel@vger.kernel.org, linux-ntfs-dev@lists.sourceforge.net, linux-f2fs-devel@lists.sourceforge.net, linux-afs@lists.infradead.org, LKML , Michal Hocko Subject: [PATCH 6/8] jbd2: make the whole kjournald2 kthread NOFS safe Date: Fri, 6 Jan 2017 15:11:05 +0100 Message-Id: <20170106141107.23953-7-mhocko@kernel.org> In-Reply-To: <20170106141107.23953-1-mhocko@kernel.org> References: <20170106141107.23953-1-mhocko@kernel.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: From: Michal Hocko kjournald2 is central to the transaction commit processing. As such any potential allocation from this kernel thread has to be GFP_NOFS. Make sure to mark the whole kernel thread GFP_NOFS by the memalloc_nofs_save. Suggested-by: Jan Kara Signed-off-by: Michal Hocko Reviewed-by: Jan Kara --- fs/jbd2/journal.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c index a097048ed1a3..3a449150f834 100644 --- a/fs/jbd2/journal.c +++ b/fs/jbd2/journal.c @@ -206,6 +206,13 @@ static int kjournald2(void *arg) wake_up(&journal->j_wait_done_commit); /* + * Make sure that no allocations from this kernel thread will ever recurse + * to the fs layer because we are responsible for the transaction commit + * and any fs involvement might get stuck waiting for the trasn. commit. + */ + memalloc_nofs_save(); + + /* * And now, wait forever for commit wakeup events. */ write_lock(&journal->j_state_lock); -- 2.11.0