On Mon, 15 Oct 2012, Ming Lei wrote: > This patch applies the introduces tsk_memalloc_forbid_io() and > tsk_memalloc_allow_io() to force memory allocation with no I/O > during runtime_resume callback. > > Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> > Cc: Oliver Neukum <oneukum@xxxxxxx> > Cc: Rafael J. Wysocki <rjw@xxxxxxx> > Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxxxxx> > --- > drivers/base/power/runtime.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c > index 3148b10..76836c1 100644 > --- a/drivers/base/power/runtime.c > +++ b/drivers/base/power/runtime.c > @@ -652,7 +652,20 @@ static int rpm_resume(struct device *dev, int rpmflags) > if (!callback && dev->driver && dev->driver->pm) > callback = dev->driver->pm->runtime_resume; > > + /* > + * Deadlock might be caused if memory allocation with GFP_KERNEL > + * happens inside runtime_resume callback of one block device's > + * ancestor or the block device itself. The easiest approach is > + * to forbid I/O inside runtime_resume of all devices. > + * > + * In fact, it can be done only if the deivce is a block device > + * or there is one block device descendant. But that may become > + * complicated and not efficient because device tree traversing > + * is involved. > + */ > + tsk_memalloc_forbid_io(current); > retval = rpm_callback(callback, dev); > + tsk_memalloc_allow_io(current); This is not so good. What happens if I/O was already forbidden when this function was called? Alan Stern -- 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
