[PATCH 01/13] PCI/P2PDMA: Release the per-cpu ref of pgmap when vm_insert_page() fails

[Hou Tao <houtao@huaweicloud.com>]

From: Hou Tao <houtao1@huawei.com>

When vm_insert_page() fails in p2pmem_alloc_mmap(), p2pmem_alloc_mmap()
doesn't invoke percpu_ref_put() to free the per-cpu ref of pgmap
acquired after gen_pool_alloc_owner(), and memunmap_pages() will hang
forever when trying to remove the PCIe device.

Fix it by adding the missed percpu_ref_put().

Fixes: 7e9c7ef83d78 ("PCI/P2PDMA: Allow userspace VMA allocations through sysfs")
Signed-off-by: Hou Tao <houtao1@huawei.com>
---
 drivers/pci/p2pdma.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
index 4a2fc7ab42c3..218c1f5252b6 100644
--- a/drivers/pci/p2pdma.c
+++ b/drivers/pci/p2pdma.c
@@ -152,6 +152,7 @@ static int p2pmem_alloc_mmap(struct file *filp, struct kobject *kobj,
 		ret = vm_insert_page(vma, vaddr, page);
 		if (ret) {
 			gen_pool_free(p2pdma->pool, (uintptr_t)kaddr, len);
+			percpu_ref_put(ref);
 			return ret;
 		}
 		percpu_ref_get(ref);
-- 
2.29.2