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

[Alistair Popple]

On 2025-12-20 at 15:04 +1100, Hou Tao <houtao at huaweicloud.com> wrote...
> From: Hou Tao <houtao1 at 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().

This pairs with the percpu_ref_tryget_live_rcu() above right? Might be worth
mentioning that as a comment, but overall looks good to me so feel free to add:

Reviewed-by: Alistair Popple <apopple at nvidia.com>

> 
> Fixes: 7e9c7ef83d78 ("PCI/P2PDMA: Allow userspace VMA allocations through sysfs")
> Signed-off-by: Hou Tao <houtao1 at 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
>