On Wednesday 10 October 2012 11:19:09 Ming Lei wrote: > On Tue, Oct 9, 2012 at 4:47 PM, Oliver Neukum <oneukum@xxxxxxx> wrote: > > > > Using GFP_KERNEL you preclude using those in resume() and error handling. > > Please pass a gfp_t parameter. > > IMO, it is not a big deal because generally only several bytes are to be > allocated inside these helpers. Any allocation can do it, if the VM layer decides to block. > If you still think the problem should be considered, another candidate fix > is to take GFP_NOIO during system suspend/resume, and take GFP_KERNEL > in other situations. No, the problem is autoresume. Suppose we have a device with two interface. Interface A be usbnet; interface B something you page on. Now consider that you can only resume both interfaces and this is (and needs to be) done synchronously. Now we can have this code path: autoresume of device -> resume() -> kmalloc(..., GFP_KERNEL) -> VM layer decides to start paging out -> IO to interface B -> autoresume of device --> DEADLOCK We need to use GFP_NOIO in situations the helper cannot know about. Please add a gfp_t parameter. Then the caller will solve that. Regards Oliver -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
