From: Peter Zijlstra <peterz@infradead.org>
To: Chris Wilson <chris@chris-wilson.co.uk>
Cc: "Fengguang Wu" <fengguang.wu@intel.com>,
"Boqun Feng" <boqun.feng@gmail.com>,
"Nicolai Hähnle" <Nicolai.Haehnle@amd.com>,
"Ingo Molnar" <mingo@kernel.org>,
linux-kernel@vger.kernel.org, LKP <lkp@01.org>
Subject: Re: [locking/ww_mutex] 2a0c112828 WARNING: CPU: 0 PID: 18 at kernel/locking/mutex.c:305 __ww_mutex_wakeup_for_backoff
Date: Wed, 1 Mar 2017 17:54:06 +0100 [thread overview]
Message-ID: <20170301165406.GZ6485@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20170301162648.GF4740@nuc-i3427.alporthouse.com>
On Wed, Mar 01, 2017 at 04:26:48PM +0000, Chris Wilson wrote:
> On Wed, Mar 01, 2017 at 04:11:48PM +0000, Chris Wilson wrote:
> > On Wed, Mar 01, 2017 at 04:54:14PM +0100, Peter Zijlstra wrote:
> > > On Wed, Mar 01, 2017 at 11:40:43PM +0800, Fengguang Wu wrote:
> > > > Thanks for the patch! I applied the patch on top of "locking/ww_mutex:
> > > > Add kselftests for ww_mutex stress", and find no "bad unlock balance
> > > > detected" but this warning. Attached is the new dmesg which is a bit
> > > > large due to lots of repeated errors.
> > >
> > > So with all the various patches it works for me.
> > >
> > > I also have the following on top; which I did when I was looking through
> > > this code trying to figure out wth was happening.
> > >
> > > Chris, does this make sense to you?
> > >
> > > It makes each loop a fully new 'instance', otherwise we'll never update
> > > the ww_class->stamp and the threads will aways have the same order.
> >
> > Sounds ok, I just thought the stamp order of the threads was
> > immaterial - with each test doing a different sequence of locks and each
> > being identical in behaviour, it would not matter which had priority,
> > there would have be some shuffling no matter waht. However, for the
> > purpose of testing, having each iteration be a new locking instance does
> > make it behaviour more like a typical user.
>
> Correcting myself, the workers didn't reorder the locks, so changing the
> stamp does make the test more interesting.
OK, so I'll go write a Changelog for it then ;-) And stick your ACK on.
next prev parent reply other threads:[~2017-03-01 21:44 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-27 5:14 [locking/ww_mutex] 2a0c112828 WARNING: CPU: 0 PID: 18 at kernel/locking/mutex.c:305 __ww_mutex_wakeup_for_backoff Fengguang Wu
2017-02-27 10:28 ` Peter Zijlstra
2017-02-27 10:35 ` Peter Zijlstra
2017-03-01 15:01 ` Boqun Feng
2017-03-01 15:18 ` Peter Zijlstra
[not found] ` <20170301154043.hcsbpgooc3kqt45j@wfg-t540p.sh.intel.com>
2017-03-01 15:51 ` Peter Zijlstra
2017-03-01 15:55 ` Fengguang Wu
2017-03-01 15:54 ` Peter Zijlstra
2017-03-01 16:11 ` Chris Wilson
2017-03-01 16:26 ` Chris Wilson
2017-03-01 16:54 ` Peter Zijlstra [this message]
2017-03-01 17:39 ` Fengguang Wu
2017-03-02 8:21 ` [tip:locking/urgent] locking/ww_mutex: Adjust the lock number for stress test tip-bot for Boqun Feng
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=20170301165406.GZ6485@twins.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=Nicolai.Haehnle@amd.com \
--cc=boqun.feng@gmail.com \
--cc=chris@chris-wilson.co.uk \
--cc=fengguang.wu@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=lkp@01.org \
--cc=mingo@kernel.org \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).