On Mon, 22 Oct 2012, Ming Lei wrote: > If one storage interface or usb network interface(iSCSI case) > exists in current configuration, memory allocation with > GFP_KERNEL during usb_device_reset() might trigger I/O transfer > on the storage interface itself and cause deadlock because > the 'us->dev_mutex' is held in .pre_reset() and the storage > interface can't do I/O transfer when the reset is triggered > by other interface, or the error handling can't be completed > if the reset is triggered by the storage itself(error handling path). > > Cc: Alan Stern <[email protected]> > Cc: Oliver Neukum <[email protected]> > Signed-off-by: Ming Lei <[email protected]> > --- > drivers/usb/core/hub.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c > index 522ad57..106a80a 100644 > --- a/drivers/usb/core/hub.c > +++ b/drivers/usb/core/hub.c > @@ -5038,6 +5038,7 @@ int usb_reset_device(struct usb_device *udev) > { > int ret; > int i; > + unsigned int noio_flag; > struct usb_host_config *config = udev->actconfig; > > if (udev->state == USB_STATE_NOTATTACHED || > @@ -5047,6 +5048,15 @@ int usb_reset_device(struct usb_device *udev) > return -EINVAL; > } > > + /* > + * Don't allocate memory with GFP_KERNEL in current > + * context to avoid possible deadlock if usb mass > + * storage interface or usbnet interface(iSCSI case) > + * is included in current configuration. The easiest > + * approach is to do it for all devices. > + */ > + memalloc_noio_save(noio_flag);
Why not check dev->power.memalloc_noio_resume here too? Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
