From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Tejun Heo <tj@kernel.org>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
Jens Axboe <axboe@kernel.dk>,
tomaz.solc@tablix.org, aaron.lu@intel.com,
linux-kernel@vger.kernel.org, Oleg Nesterov <oleg@redhat.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Fengguang Wu <fengguang.wu@intel.com>
Subject: Re: [PATCH] libata, freezer: avoid block device removal while system is frozen
Date: Wed, 18 Dec 2013 01:23:57 +0100 [thread overview]
Message-ID: <18258432.12ryrov20c@vostro.rjw.lan> (raw)
In-Reply-To: <20131217123643.GE29989@htj.dyndns.org>
On Tuesday, December 17, 2013 07:36:43 AM Tejun Heo wrote:
> Hello, Rafael.
>
> On Tue, Dec 17, 2013 at 03:38:05AM +0100, Rafael J. Wysocki wrote:
> > On Friday, December 13, 2013 03:40:34 PM Tejun Heo wrote:
> > > Hello,
> > >
> > > So, this is the laughable workaround that I came up with. Seriously,
> > > this is tragic. :(
> > >
> > > Thanks.
> > >
> > > ------- 8< -------
> > > Freezable kthreads and workqueues are fundamentally problematic in
> > > that they effectively introduce a big kernel lock widely used in the
> > > kernel and have already been the culprit of several deadlock
> > > scenarios. This is the latest occurrence.
> >
> > OK, so I'm too tired now to go through all that, but I'll look at it tomorrow.
> >
> > The rule of thumb is to get rid of freezable kernel threads in the first
> > place if possible anyway if they are causing problems to happen.
>
> Yes, that'd be awesome. In fact, getting rid of all kernel freezables
> in non-low-level-drivers would be a great step forward.
Agreed.
> That said, we need something easily backportable so I think we probably need
> this bandaid for immediate fix for now.
Well, we need something, but I have a couple of concerns about this particular
patch (I'll reply to it with comments shortly).
Thanks,
Rafael
next prev parent reply other threads:[~2013-12-18 0:10 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-13 17:49 Writeback threads and freezable Tejun Heo
2013-12-13 18:52 ` Tejun Heo
2013-12-13 20:40 ` [PATCH] libata, freezer: avoid block device removal while system is frozen Tejun Heo
2013-12-13 22:45 ` Nigel Cunningham
2013-12-13 23:07 ` Tejun Heo
2013-12-13 23:15 ` Nigel Cunningham
2013-12-14 1:55 ` Dave Chinner
2013-12-14 20:31 ` Tejun Heo
2013-12-14 20:36 ` Tejun Heo
2013-12-14 21:21 ` Nigel Cunningham
2013-12-17 2:35 ` Rafael J. Wysocki
2013-12-17 2:34 ` Rafael J. Wysocki
2013-12-17 12:34 ` Tejun Heo
2013-12-18 0:35 ` Rafael J. Wysocki
2013-12-18 11:17 ` Tejun Heo
2013-12-18 21:48 ` Rafael J. Wysocki
2013-12-18 21:39 ` Tejun Heo
2013-12-18 21:41 ` Tejun Heo
2013-12-18 22:04 ` Rafael J. Wysocki
2013-12-19 23:35 ` [PATCH wq/for-3.14 1/2] workqueue: update max_active clamping rules Tejun Heo
2013-12-20 1:26 ` Rafael J. Wysocki
2013-12-19 23:37 ` [PATCH wq/for-3.14 2/2] workqueue: implement @drain for workqueue_set_max_active() Tejun Heo
2013-12-20 1:31 ` Rafael J. Wysocki
2013-12-20 13:32 ` Tejun Heo
2013-12-20 13:56 ` Rafael J. Wysocki
2013-12-20 14:23 ` Tejun Heo
2013-12-16 12:12 ` [PATCH] libata, freezer: avoid block device removal while system is frozen Ming Lei
2013-12-16 12:45 ` Tejun Heo
2013-12-16 13:24 ` Ming Lei
2013-12-16 16:05 ` Tejun Heo
2013-12-17 2:38 ` Rafael J. Wysocki
2013-12-17 12:36 ` Tejun Heo
2013-12-18 0:23 ` Rafael J. Wysocki [this message]
2013-12-17 12:50 ` [PATCH v2] " Tejun Heo
2013-12-18 1:04 ` Rafael J. Wysocki
2013-12-18 11:08 ` Tejun Heo
2013-12-18 12:07 ` [PATCH v3] " Tejun Heo
2013-12-18 22:08 ` Rafael J. Wysocki
2013-12-19 17:24 ` Tejun Heo
2013-12-19 18:54 ` [PATCH v4] " Tejun Heo
2013-12-14 1:53 ` Writeback threads and freezable Dave Chinner
2013-12-14 17:30 ` Greg Kroah-Hartman
2013-12-14 20:23 ` Tejun Heo
2013-12-16 3:56 ` Dave Chinner
2013-12-16 12:51 ` Tejun Heo
2013-12-16 12:56 ` Tejun Heo
2013-12-18 0:35 ` Dave Chinner
2013-12-18 11:43 ` Tejun Heo
2013-12-18 22:14 ` Rafael J. Wysocki
2013-12-19 4:08 ` Dave Chinner
2013-12-19 16:24 ` Tejun Heo
2013-12-20 0:51 ` Dave Chinner
2013-12-20 14:51 ` Tejun Heo
2013-12-20 14:00 ` Rafael J. Wysocki
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