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Date: Sat, 3 Nov 2012 16:35:14 +0800 From: Ming Lei <ming.lei@...onical.com> To: linux-kernel@...r.kernel.org Cc: Alan Stern <stern@...land.harvard.edu>, Oliver Neukum <oneukum@...e.de>, 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, Ming Lei <ming.lei@...onical.com> Subject: [PATCH v4 6/6] USB: forbid memory allocation with I/O during bus reset 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 <stern@...land.harvard.edu> Cc: Oliver Neukum <oneukum@...e.de> Signed-off-by: Ming Lei <ming.lei@...onical.com> --- v4: - mark current memalloc_noio for every usb device reset --- drivers/usb/core/hub.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index 5b131b6..788e652 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -5044,6 +5044,7 @@ 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 || @@ -5053,6 +5054,17 @@ 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 easist + * approach is to do it for every device reset, + * because the device 'memalloc_noio' flag may have + * not been set before reseting the usb device. + */ + memalloc_noio_save(noio_flag); + /* Prevent autosuspend during the reset */ usb_autoresume_device(udev); @@ -5097,6 +5109,7 @@ int usb_reset_device(struct usb_device *udev) } usb_autosuspend_device(udev); + memalloc_noio_restore(noio_flag); return ret; } EXPORT_SYMBOL_GPL(usb_reset_device); -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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