On Fri, 2019-04-19 at 15:34:13 UTC, Greg Kurz wrote:
> Since 902bdc57451c, get_pci_dev() calls pci_get_domain_bus_and_slot(). This
> has the effect of incrementing the reference count of the PCI device, as
> explained in drivers/pci/search.c:
>
> * Given a PCI domain, bus, and slot/function number, the desired PCI
> * device is located in the list of PCI devices. If the device is
> * found, its reference count is increased and this function returns a
> * pointer to its data structure. The caller must decrement the
> * reference count by calling pci_dev_put(). If no device is found,
> * %NULL is returned.
>
> Nothing was done to call pci_dev_put() and the reference count of GPU and
> NPU PCI devices rockets up.
>
> A natural way to fix this would be to teach the callers about the change,
> so that they call pci_dev_put() when done with the pointer. This turns
> out to be quite intrusive, as it affects many paths in npu-dma.c,
> pci-ioda.c and vfio_pci_nvlink2.c. Also, the issue appeared in 4.16 and
> some affected code got moved around since then: it would be problematic
> to backport the fix to stable releases.
>
> All that code never cared for reference counting anyway. Call pci_dev_put()
> from get_pci_dev() to revert to the previous behavior.
>
> Fixes: 902bdc57451c ("powerpc/powernv/idoa: Remove unnecessary pcidev from
> pci_dn")
> Cc: sta...@vger.kernel.org # v4.16
> Signed-off-by: Greg Kurz <gr...@kaod.org>
> Reviewed-by: Alexey Kardashevskiy <a...@ozlabs.ru>
Applied to powerpc next, thanks.
https://git.kernel.org/powerpc/c/02c5f5394918b9b47ff4357b1b183357
cheers
