From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx108.postini.com [74.125.245.108]) by kanga.kvack.org (Postfix) with SMTP id 6E3006B0062 for ; Mon, 22 Oct 2012 10:37:10 -0400 (EDT) Date: Mon, 22 Oct 2012 10:37:09 -0400 (EDT) From: Alan Stern 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: owner-linux-mm@kvack.org List-ID: 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 , netdev@vger.kernel.org, linux-usb@vger.kernel.org, linux-pm@vger.kernel.org, linux-mm@kvack.org 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org