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From: Nigel Cunningham <nigel@nigelcunningham.com.au>
To: Tejun Heo <tj@kernel.org>,
	"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
	Jens Axboe <axboe@kernel.dk>
Cc: 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: Sat, 14 Dec 2013 09:45:59 +1100	[thread overview]
Message-ID: <52AB8E27.90308@nigelcunningham.com.au> (raw)
In-Reply-To: <20131213204034.GE27070@htj.dyndns.org>

Hi Tejun.

Thanks for your work on this.

In your first email, in the first substantial paragraph (starting "Now, 
if the rest.."), you say "libata device removal waits for the scheduled 
writeback work item to finish". I wonder if that's the lynchpin. If we 
know the device is gone, why are we trying to write to it?

All pending I/O should have been flushed when suspend/hibernate started, 
and there's no point in trying to update metadata on a device we can't 
access, so there should be no writeback needed (and anything that does 
somehow get there should just be discarded since it will never succeed 
anyway).

Or am I missing something?

Having said the above, I agree that we shouldn't need to freeze kernel 
threads and workqueues themselves. I think we should be giving the 
producers of I/O the nous needed to avoid producing I/O during 
suspend/hibernate. But perhaps I'm missing something here, too.

Regards,

Nigel

  reply	other threads:[~2013-12-13 22:53 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 [this message]
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
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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