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

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Message-ID: <7ee29764-487a-4b23-8580-a9f45d73e088@deltatee.com>
Date: Mon, 22 Dec 2025 09:49:41 -0700
From: Logan Gunthorpe <logang@...tatee.com>
To: Hou Tao <houtao@...weicloud.com>, linux-kernel@...r.kernel.org
Cc: linux-pci@...r.kernel.org, linux-mm@...ck.org,
 linux-nvme@...ts.infradead.org, Bjorn Helgaas <bhelgaas@...gle.com>,
 Alistair Popple <apopple@...dia.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 2025-12-19 21:04, Hou Tao 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().
> 
> Fixes: 7e9c7ef83d78 ("PCI/P2PDMA: Allow userspace VMA allocations through sysfs")
> Signed-off-by: Hou Tao <houtao1@...wei.com>
Nice catch, thanks:

Reviewed-by: Logan Gunthorpe <logang@...tatee.com>

Logan