Re: [RFC PATCH v3 3/3] acpi_memhotplug: Allow eject to proceed onrebind scenario
From: Toshi Kani
Date: Thu Dec 06 2012 - 10:50:20 EST
On Thu, 2012-12-06 at 13:50 +0100, Rafael J. Wysocki wrote:
> On Thursday, December 06, 2012 10:30:19 AM Vasilis Liaskovitis wrote:
> > Hi,
> > On Thu, Nov 29, 2012 at 10:44:11AM -0700, Toshi Kani wrote:
> > > On Thu, 2012-11-29 at 12:04 +0100, Vasilis Liaskovitis wrote:
> > >
> > > Yes, that's what I had in mind along with device_lock(). I think the
> > > lock is necessary to close the window.
> > > http://www.spinics.net/lists/linux-mm/msg46973.html
> > >
> > > But as I mentioned in other email, I prefer option 3 with
> > > suppress_bind_attrs. So, yes, please take a look to see how it works
> > > out.
> > I tested the suppress_bind_attrs and it works by simply setting it to true
> > before driver registration e.g.
> > --- a/drivers/acpi/scan.c
> > +++ b/drivers/acpi/scan.c
> > @@ -783,7 +783,8 @@ int acpi_bus_register_driver(struct acpi_driver *driver)
> > driver->drv.name = driver->name;
> > driver->drv.bus = &acpi_bus_type;
> > driver->drv.owner = driver->owner;
> > -
> > + if (!strcmp(driver->class, "memory"))
> > + driver->drv.suppress_bind_attrs = true;
> > ret = driver_register(&driver->drv);
> > return ret;
> > }
> > No bind/unbind sysfs files are created when using this, as expected.
> > I assume we only want to suppress for acpi_memhotplug
> > (class=ACPI_MEMORY_DEVICE_CLASS i.e. "memory") devices.
> > Is there agreement on what acpi_bus_trim behaviour and rollback (if any) we
> > want to have for the current ACPI framework (partial trim or full trim on
> > failure)?
> Last time I suggested to split the trimming so that first we only unbind
> drivers (and roll back that part, ie. rebind the drivers on errors) and
> next we remove the struct acpi_device objects, just before doing the actual
> eject. So there would be two walks of the hierarchy below the device we want
> to eject, one for driver unbinding (that can be rolled back) and one for the
> actual removal.
> Toshi Kani seemed to agree with that and there were no follow-ups.
I was hoping to have a short term solution to fix the panic on
attempting to delete a kernel memory range, assuming that the memory
hot-plug feature is going to make into 3.8. It's a blocker issue for
testing the feature. Now that the VM patchset does not seem to make
into 3.8, I think we can step back and focus on a long term solution
I agree that we should separate resource online/offlining step and
acpi_device creation/deletion step. It can address the panic and make
rollback easier to handle. For 3.9, we should have a better framework
in place to handle it in general. So, I am currently working on a
framework proposal, and hopefully able to send it out in a week or so.
Lastly, thanks Vasilis for testing the suppress_bind_attrs change. I
think we may still need it for 3.9.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/