From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Tejun Heo <tj@kernel.org>
Cc: linux-kernel@vger.kernel.org, torvalds@linux-foundation.org,
peterz@infradead.org, tglx@linutronix.de,
linux-pm@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH] workqueue: fix spurious CPU locality WARN from process_one_work()
Date: Sun, 22 Jul 2012 14:23:58 -0700 [thread overview]
Message-ID: <20120722212358.GT2435@linux.vnet.ibm.com> (raw)
In-Reply-To: <20120722164327.GA5144@dhcp-172-17-108-109.mtv.corp.google.com>
On Sun, Jul 22, 2012 at 09:43:27AM -0700, Tejun Heo wrote:
> 25511a4776 "workqueue: reimplement CPU online rebinding to handle idle
> workers" added CPU locality sanity check in process_one_work(). It
> triggers if a worker is executing on a different CPU without UNBOUND
> or REBIND set.
>
> This works for all normal workers but rescuers can trigger this
> spuriously when they're serving the unbound or a disassociated
> global_cwq - rescuers don't have either flag set and thus its
> gcwq->cpu can be a different value including %WORK_CPU_UNBOUND.
>
> Fix it by additionally testing %GCWQ_DISASSOCIATED.
>
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Reported-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
> LKML-Refence: <20120721213656.GA7783@linux.vnet.ibm.com>
> ---
> This should fix it. Will queue it on wq/for-3.6.
I am running my tests on it, will let you know how it goes.
Thanx, Paul
> Thanks!
>
> kernel/workqueue.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> --- a/kernel/workqueue.c
> +++ b/kernel/workqueue.c
> @@ -1949,7 +1949,13 @@ __acquires(&gcwq->lock)
>
> lockdep_copy_map(&lockdep_map, &work->lockdep_map);
> #endif
> + /*
> + * Ensure we're on the correct CPU. DISASSOCIATED test is
> + * necessary to avoid spurious warnings from rescuers servicing the
> + * unbound or a disassociated gcwq.
> + */
> WARN_ON_ONCE(!(worker->flags & (WORKER_UNBOUND | WORKER_REBIND)) &&
> + !(gcwq->flags & GCWQ_DISASSOCIATED) &&
> raw_smp_processor_id() != gcwq->cpu);
>
> /*
>
next prev parent reply other threads:[~2012-07-22 21:24 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-17 17:12 [PATCHSET] workqueue: reimplement CPU hotplug to keep idle workers Tejun Heo
2012-07-17 17:12 ` [PATCH 1/9] workqueue: perform cpu down operations from low priority cpu_notifier() Tejun Heo
2012-07-20 21:52 ` Paul E. McKenney
2012-07-20 21:58 ` Tejun Heo
2012-07-21 21:36 ` Paul E. McKenney
2012-07-22 16:43 ` [PATCH] workqueue: fix spurious CPU locality WARN from process_one_work() Tejun Heo
2012-07-22 21:23 ` Paul E. McKenney [this message]
2012-07-17 17:12 ` [PATCH 2/9] workqueue: drop CPU_DYING notifier operation Tejun Heo
2012-07-17 17:12 ` [PATCH 3/9] workqueue: ROGUE workers are UNBOUND workers Tejun Heo
2012-07-17 17:12 ` [PATCH 4/9] workqueue: use mutex for global_cwq manager exclusion Tejun Heo
2012-07-17 17:12 ` [PATCH 5/9] workqueue: drop @bind from create_worker() Tejun Heo
2012-07-17 17:12 ` [PATCH 6/9] workqueue: reimplement CPU online rebinding to handle idle workers Tejun Heo
2012-07-17 17:12 ` [PATCH 7/9] workqueue: don't butcher idle workers on an offline CPU Tejun Heo
2012-07-17 17:12 ` [PATCH 8/9] workqueue: remove CPU offline trustee Tejun Heo
2012-07-17 17:12 ` [PATCH 9/9] workqueue: simplify CPU hotplug code Tejun Heo
2012-07-17 18:43 ` [PATCHSET] workqueue: reimplement CPU hotplug to keep idle workers Rafael J. Wysocki
2012-07-17 19:40 ` Tejun Heo
2012-07-20 15:48 ` Peter Zijlstra
2012-07-20 17:02 ` Tejun Heo
2012-07-20 17:21 ` Peter Zijlstra
2012-07-20 17:50 ` Tejun Heo
2012-07-20 18:22 ` Peter Zijlstra
2012-07-20 18:34 ` Tejun Heo
2012-07-20 19:44 ` Rafael J. Wysocki
2012-07-20 19:41 ` Tejun Heo
2012-07-21 6:42 ` Shilimkar, Santosh
2012-07-23 8:38 ` Peter De Schrijver
2012-07-20 16:39 ` Peter Zijlstra
2012-07-20 16:52 ` Tejun Heo
2012-07-20 17:01 ` Peter Zijlstra
2012-07-20 17:08 ` Tejun Heo
2012-07-20 17:19 ` Peter Zijlstra
2012-07-20 17:43 ` Tejun Heo
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=20120722212358.GT2435@linux.vnet.ibm.com \
--to=paulmck@linux.vnet.ibm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=peterz@infradead.org \
--cc=stable@vger.kernel.org \
--cc=tglx@linutronix.de \
--cc=tj@kernel.org \
--cc=torvalds@linux-foundation.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