On Fri, Nov 30, 2018 at 03:59:11PM -0700, Logan Gunthorpe wrote:
> "mm-hmm-mark-hmm_devmem_add-add_resource-export_symbol_gpl.patch" in the
> mm tree breaks p2pdma. The patch was written and reviewed before p2pdma
> was merged so the necessary changes were not done to the call site in
> that code.
>
> Without this patch, all drivers will fail to register P2P resources
> because devm_memremap_pages() will return -EINVAL due to the 'kill'
> member of the pagemap structure not yet being set.
>
> Signed-off-by: Logan Gunthorpe <log...@deltatee.com>
> Cc: Andrew Morton <a...@linux-foundation.org>
> Cc: Dan Williams <dan.j.willi...@intel.com>
> Cc: Bjorn Helgaas <bhelg...@google.com>
Applied with Dan's reviewed-by to pci/peer-to-peer for v4.21, thanks!
If the mm patch you mention gets merged for v4.20, let me know and I can
promote this to for-linus so v4.20 doesn't end up broken.
> ---
>
> Ideally this patch should be squashed with the one mentioned above to
> avoid a bisect regression point.
>
> drivers/pci/p2pdma.c | 10 ++--------
> 1 file changed, 2 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
> index ae3c5b25dcc7..a2eb25271c96 100644
> --- a/drivers/pci/p2pdma.c
> +++ b/drivers/pci/p2pdma.c
> @@ -82,10 +82,8 @@ static void pci_p2pdma_percpu_release(struct percpu_ref
> *ref)
> complete_all(&p2p->devmap_ref_done);
> }
>
> -static void pci_p2pdma_percpu_kill(void *data)
> +static void pci_p2pdma_percpu_kill(struct percpu_ref *ref)
> {
> - struct percpu_ref *ref = data;
> -
> /*
> * pci_p2pdma_add_resource() may be called multiple times
> * by a driver and may register the percpu_kill devm action multiple
> @@ -198,6 +196,7 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int
> bar, size_t size,
> pgmap->type = MEMORY_DEVICE_PCI_P2PDMA;
> pgmap->pci_p2pdma_bus_offset = pci_bus_address(pdev, bar) -
> pci_resource_start(pdev, bar);
> + pgmap->kill = pci_p2pdma_percpu_kill;
>
> addr = devm_memremap_pages(&pdev->dev, pgmap);
> if (IS_ERR(addr)) {
> @@ -211,11 +210,6 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int
> bar, size_t size,
> if (error)
> goto pgmap_free;
>
> - error = devm_add_action_or_reset(&pdev->dev, pci_p2pdma_percpu_kill,
> - &pdev->p2pdma->devmap_ref);
> - if (error)
> - goto pgmap_free;
> -
> pci_info(pdev, "added peer-to-peer DMA memory %pR\n",
> &pgmap->res);
>
> --
> 2.19.0
