From mboxrd@z Thu Jan 1 00:00:00 1970 From: Junxiao Bi Date: Tue, 15 Dec 2015 09:43:48 +0800 Subject: [Ocfs2-devel] [PATCH] ocfs2: dlm: fix recursive locking deadlock In-Reply-To: <20151214191827.GF11072@wotan.suse.de> References: <1450058259-30682-1-git-send-email-junxiao.bi@oracle.com> <566EC6A8020000F90002219D@relay2.provo.novell.com> <566E5BA5.5030308@oracle.com> <20151214191827.GF11072@wotan.suse.de> Message-ID: <566F7054.8030501@oracle.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: ocfs2-devel@oss.oracle.com Hi Mark, On 12/15/2015 03:18 AM, Mark Fasheh wrote: > On Mon, Dec 14, 2015 at 02:03:17PM +0800, Junxiao Bi wrote: >>> Second, this issue can be reproduced in old Linux kernels (e.g. 3.16.7-24)? there should not be any regression issue? >> Maybe just hard to reproduce, ocfs2 supports recursive locking. > > In what sense? The DLM might but the FS should never be making use of such a > mechanism (it would be for userspace users). See commit 743b5f1434f5 ("ocfs2: take inode lock in ocfs2_iop_set/get_acl()"), it used recursive locking and caused a deadlock, the call trace is in this patch's log. > > We really can't add recursive locks without this getting rejected upstream. > There's a whole slew of reasons why we don't like those in the kernel. Is there any harm to support this lock in kernel? Thanks, Junxiao. > --Mark > > -- > Mark Fasheh >