All of lore.kernel.org
 help / color / mirror / Atom feed
From: Eric Ren <zren@suse.com>
To: ocfs2-devel@oss.oracle.com
Subject: [Ocfs2-devel] [PATCH] ocfs2: dlm: fix recursive locking deadlock
Date: Mon, 14 Dec 2015 16:57:01 +0800	[thread overview]
Message-ID: <20151214085701.GB7837@desktop.lab.bej.apac.novell.com> (raw)
In-Reply-To: <566E5BA5.5030308@oracle.com>

Hi,

On Mon, Dec 14, 2015 at 02:03:17PM +0800, Junxiao Bi wrote: 
> On 12/14/2015 01:39 PM, Gang He wrote:
> > Hello Junxiao,
> > 
> > From the initial description, the second lock_XYZ(PR) should be blocked, since DLM have a fair queue  mechanism, otherwise, it looks to bring a write lock starvation.
> Should be blocked? No, that is a deadlock. I don't think this recursive
> locking is common, so no need care starvation here.
"not common" is really good news. I think we should list recursive use
cases first and try to decrease that use before messing up "__ocfs2_cluster_lock"
further. As for this patch,  cost is too high :/

Thanks,
Eric
> 
> > 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.
> 
> > Finally, really do not like nested using lock, can we avoid this.
> I didn't see a good reason why this should be avoided. Without this,
> developer needs pay more attend to not involve recursive locking,
> usually that is very hard before run a full test or a very detailed review.
> 
> Thanks,
> Junxiao.
> > 
> > Thanks
> > Gang
> > 
> > 
> 
> 
> _______________________________________________
> Ocfs2-devel mailing list
> Ocfs2-devel at oss.oracle.com
> https://oss.oracle.com/mailman/listinfo/ocfs2-devel
> 

  reply	other threads:[~2015-12-14  8:57 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-12-14  1:57 [Ocfs2-devel] [PATCH] ocfs2: dlm: fix recursive locking deadlock Junxiao Bi
2015-12-14  5:39 ` Gang He
2015-12-14  6:03   ` Junxiao Bi
2015-12-14  8:57     ` Eric Ren [this message]
2015-12-14 15:07       ` Junxiao Bi
2015-12-14 19:18     ` Mark Fasheh
2015-12-15  1:43       ` Junxiao Bi
2015-12-18 23:23         ` Mark Fasheh
2015-12-21  5:12           ` Junxiao Bi
2015-12-22 22:12             ` Mark Fasheh
2015-12-23  2:18               ` Junxiao Bi
2015-12-14  8:44 ` Eric Ren
2015-12-14  9:02   ` Junxiao Bi
2015-12-14 10:14     ` Eric Ren

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20151214085701.GB7837@desktop.lab.bej.apac.novell.com \
    --to=zren@suse.com \
    --cc=ocfs2-devel@oss.oracle.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.