Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755101Ab2JVOhM (ORCPT ); Mon, 22 Oct 2012 10:37:12 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:53273 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1754116Ab2JVOhK (ORCPT ); Mon, 22 Oct 2012 10:37:10 -0400 Date: Mon, 22 Oct 2012 10:37:09 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Ming Lei cc: linux-kernel@vger.kernel.org, Oliver Neukum , Minchan Kim , Greg Kroah-Hartman , "Rafael J. Wysocki" , Jens Axboe , "David S. Miller" , Andrew Morton , , , , Subject: Re: [RFC PATCH v2 6/6] USB: forbid memory allocation with I/O during bus reset In-Reply-To: <1350894794-1494-7-git-send-email-ming.lei@canonical.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1899 Lines: 52 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 > Cc: Oliver Neukum > Signed-off-by: Ming Lei > --- > 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 majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/