On 21.02.2015 [11:00:50 -0800], Nishanth Aravamudan wrote:

On 20.02.2015 [15:31:29 +1100], Michael Ellerman wrote:

quoted

On Thu, 2015-02-19 at 10:41 -0800, Nishanth Aravamudan wrote:

quoted

After d905c5df9aef ("PPC: POWERNV: move iommu_add_device earlier"), the
refcnt on the kobject backing the IOMMU group for a PCI device is
elevated by each call to pci_dma_dev_setup_pSeriesLP() (via
set_iommu_table_base_and_group). When we go to dlpar a multi-function
PCI device out:

	iommu_reconfig_notifier ->
		iommu_free_table ->
			iommu_group_put
			BUG_ON(tbl->it_group)

We trip this BUG_ON, because there are still references on the table, so
it is not freed. Fix this by also adding a bus notifier identical to
PowerNV for pSeries.

Please put it somewhere common, arch/powerpc/kernel/iommu.c perhaps, and just
add a second machine_init_call() for pseries.

How does this look? Only compile-tested with CONFIG_IOMMU_API on/off so
far, waiting for access to the test LPAR (should have it on Monday).


After d905c5df9aef ("PPC: POWERNV: move iommu_add_device earlier"), the
refcnt on the kobject backing the IOMMU group for a PCI device is
elevated by each call to pci_dma_dev_setup_pSeriesLP() (via
set_iommu_table_base_and_group). When we go to dlpar a multi-function
PCI device out:

        iommu_reconfig_notifier ->
                iommu_free_table ->
                        iommu_group_put
                        BUG_ON(tbl->it_group)

We trip this BUG_ON, because there are still references on the table, so
it is not freed. Fix this by moving the PowerNV bus notifier to common
code and calling it for both PowerNV and pSeries.

Survived a remove -> add -> remove cycle, which always resulted in the
BUG_ON without the change.

Fixes: d905c5df9aef ("PPC: POWERNV: move iommu_add_device earlier")
Signed-off-by: Nishanth Aravamudan <redacted>
Cc: stable@kernel.org (3.13+)

Tested-by: Nishanth Aravamudan <redacted>