[PATCH v2 3/6] PCI/P2PDMA: Fix the gen_pool_add_virt() failure path

[Dan Williams <dan.j.williams@intel.com>]

The pci_p2pdma_add_resource() implementation immediately frees the pgmap
if gen_pool_add_virt() fails. However, that means that when @dev
triggers a devres release devm_memremap_pages_release() will crash
trying to access the freed @pgmap.

Use the new devm_memunmap_pages() to manually free the mapping in the
error path.

Fixes: 52916982af48 ("PCI/P2PDMA: Support peer-to-peer memory")
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/pci/p2pdma.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
index c52298d76e64..595a534bd749 100644
--- a/drivers/pci/p2pdma.c
+++ b/drivers/pci/p2pdma.c
@@ -208,13 +208,15 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size,
 			pci_bus_address(pdev, bar) + offset,
 			resource_size(&pgmap->res), dev_to_node(&pdev->dev));
 	if (error)
-		goto pgmap_free;
+		goto pages_free;
 
 	pci_info(pdev, "added peer-to-peer DMA memory %pR\n",
 		 &pgmap->res);
 
 	return 0;
 
+pages_free:
+	devm_memunmap_pages(&pdev->dev, pgmap);
 pgmap_free:
 	devm_kfree(&pdev->dev, pgmap);
 	return error;