linux-kernel - Re: [PATCH 01/13] PCI/P2PDMA: Release the per-cpu ref of pgmap when vm_insert

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <46lz5szq44vz3chzj6unh2sff4cfnpyvih7zty6fcnitzyrulu@6a2xdopoafxt>
Date: Thu, 8 Jan 2026 14:23:16 +1100
From: Alistair Popple <apopple@...dia.com>
To: Hou Tao <houtao@...weicloud.com>
Cc: linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org, 
	linux-mm@...ck.org, linux-nvme@...ts.infradead.org, 
	Bjorn Helgaas <bhelgaas@...gle.com>, Logan Gunthorpe <logang@...tatee.com>, 
	Leon Romanovsky <leonro@...dia.com>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
	Tejun Heo <tj@...nel.org>, "Rafael J . Wysocki" <rafael@...nel.org>, 
	Danilo Krummrich <dakr@...nel.org>, Andrew Morton <akpm@...ux-foundation.org>, 
	David Hildenbrand <david@...nel.org>, Lorenzo Stoakes <lorenzo.stoakes@...cle.com>, 
	Keith Busch <kbusch@...nel.org>, Jens Axboe <axboe@...nel.dk>, Christoph Hellwig <hch@....de>, 
	Sagi Grimberg <sagi@...mberg.me>, houtao1@...wei.com
Subject: Re: [PATCH 01/13] PCI/P2PDMA: Release the per-cpu ref of pgmap when
 vm_insert_page() fails

On 2025-12-20 at 15:04 +1100, Hou Tao <houtao@...weicloud.com> wrote...
> From: Hou Tao <houtao1@...wei.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@...dia.com>

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