On Wed, Oct 31, 2012 at 10:08 AM, Ming Lei [off-list ref] wrote:

quoted

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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