On Friday, November 16, 2012 01:33:10 PM Greg Kroah-Hartman wrote: > On Fri, Nov 16, 2012 at 10:17:17PM +0100, Rafael J. Wysocki wrote: > > On Thursday, November 15, 2012 11:22:47 AM Vasilis Liaskovitis wrote: > > > As discussed in https://patchwork.kernel.org/patch/1581581/ > > > the driver core remove function needs to always succeed. This means we need > > > to know that the device can be successfully removed before acpi_bus_trim / > > > acpi_bus_hot_remove_device are called. This can cause panics when OSPM-initiated > > > eject or driver unbind of memory devices fails e.g with: > > > > > > echo 1 >/sys/bus/pci/devices/PNP0C80:XX/eject > > > echo "PNP0C80:XX" > /sys/bus/acpi/drivers/acpi_memhotplug/unbind > > > > > > since the ACPI core goes ahead and ejects the device regardless of whether the > > > the memory is still in use or not. > > > > > > For this reason a new acpi_device operation called prepare_remove is introduced. > > > This operation should be registered for acpi devices whose removal (from kernel > > > perspective) can fail. Memory devices fall in this category. > > > A similar operation is introduced in bus_type to safely handle driver unbind > > > from the device driver core. > > > > > > acpi_bus_hot_remove_device and driver_unbind are changed to handle removal in 2 > > > steps: > > > - preparation for removal i.e. perform part of removal that can fail. Should > > > succeed for device and all its children. > > > - if above step was successfull, proceed to actual device removal > > > > > > With this patchset, only acpi memory devices use the new prepare_remove > > > device operation. The actual memory removal (VM-related offline and other memory > > > cleanups) is moved to prepare_remove. The old remove operation just cleans up > > > the acpi structures. Directly ejecting PNP0C80 memory devices works safely. I > > > haven't tested yet with an ACPI container which contains memory devices. > > > > > > v1->v2: > > > - new patch to introduce bus_type prepare_remove callback. Needed to prepare > > > removal on driver unbinding from device-driver core. > > > - v1 patches 1 and 2 simplified and merged in one. acpi_bus_trim does not require > > > argument changes. > > > > > > Comments welcome. > > > > > > Vasilis Liaskovitis (3): > > > driver core: Introduce prepare_remove in bus_type > > > acpi: Introduce prepare_remove operation in acpi_device_ops > > > acpi_memhotplug: Add prepare_remove operation > > > > > > drivers/acpi/acpi_memhotplug.c | 22 ++++++++++++++++++++-- > > > drivers/acpi/scan.c | 21 ++++++++++++++++++++- > > > drivers/base/bus.c | 36 ++++++++++++++++++++++++++++++++++++ > > > include/acpi/acpi_bus.h | 2 ++ > > > include/linux/device.h | 2 ++ > > > 5 files changed, 80 insertions(+), 3 deletions(-) > > > > CCs of all driver core patches have to go to Greg Kroah-Hartman. > > I previously rejected this, so I don't see why I would take it this time > around :( > > Please, no driver core changes for acpi, I don't see why it is suddenly > so special to need stuff like this that can't just be done in the ACPI > bus code itself. OK, OK, that was just a notice to the author. :-) Thanks, Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>