linux-kernel - Re: [PATCH v3 2/6] PM / Runtime: introduce pm_runtime_set[get]_memalloc

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Message-ID: <CACVXFVNxucCVLS-=EQkmVop3LQMkeXW7RbZq4yfkiq_MUGndvg@mail.gmail.com>
Date:	Wed, 31 Oct 2012 11:05:33 +0800
From:	Ming Lei <ming.lei@...onical.com>
To:	Oliver Neukum <oneukum@...e.de>
Cc:	Alan Stern <stern@...land.harvard.edu>,
	linux-kernel@...r.kernel.org, Minchan Kim <minchan@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>, Jens Axboe <axboe@...nel.dk>,
	"David S. Miller" <davem@...emloft.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	netdev@...r.kernel.org, linux-usb@...r.kernel.org,
	linux-pm@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v3 2/6] PM / Runtime: introduce pm_runtime_set[get]_memalloc_noio()

On Wed, Oct 31, 2012 at 10:08 AM, Ming Lei <ming.lei@...onical.com> wrote:
>> I am afraid it is, because a disk may just have been probed as the deviceis being reset.
>
> Yes, it is probable, and sounds like similar with 'root_wait' problem, see
> prepare_namespace(): init/do_mounts.c, so looks no good solution
> for the problem, and maybe we have to set the flag always before resetting
> usb device.

The below idea may help the problem which 'memalloc_noio' flag isn't set during
usb_reset_device().

- for usb mass storage device, call pm_runtime_set_memalloc_noio(true)
  inside usb_stor_probe2() and uas_probe(), and call
  pm_runtime_set_memalloc_noio(false) inside uas_disconnect()
  and usb_stor_disconnect().

- for usb network device, register_netdev() is always called inside usb
  interface's probe(),  looks no such problem.

Thanks,
--
Ming Lei
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