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 <st...@rowland.harvard.edu> Cc: Oliver Neukum <oneu...@suse.de> Signed-off-by: Ming Lei <ming....@canonical.com> --- 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 9dc8ff2..3ea81f6 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -5028,6 +5028,7 @@ 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 || @@ -5037,6 +5038,15 @@ 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); + /* Prevent autosuspend during the reset */ usb_autoresume_device(udev); @@ -5081,6 +5091,7 @@ 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 majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/