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Date: Wed, 5 Jun 2024 16:45:00 -0500
From: Bjorn Helgaas <helgaas@kernel.org>
To: Martin Oliveira <martin.oliveira@eideticom.com>
Cc: linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-pci@vger.kernel.org, linux-mm@kvack.org,
	Jason Gunthorpe <jgg@ziepe.ca>, Leon Romanovsky <leon@kernel.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Logan Gunthorpe <logang@deltatee.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Tejun Heo <tj@kernel.org>, "Rafael J. Wysocki" <rafael@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Mike Marciniszyn <mike.marciniszyn@intel.com>,
	Michael Guralnik <michaelgur@nvidia.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	Valentine Sinitsyn <valesini@yandex-team.ru>,
	Lukas Wunner <lukas@wunner.de>
Subject: Re: [PATCH 3/6] PCI/P2PDMA: create VMA without page_mkwrite()
 operator
Message-ID: <20240605214500.GA781636@bhelgaas>
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In-Reply-To: <20240605192934.742369-4-martin.oliveira@eideticom.com>

On Wed, Jun 05, 2024 at 01:29:31PM -0600, Martin Oliveira wrote:
> The P2PDMA code does not need (or want) a page_mkwrite() operator on its
> VMA.
> 
> Furthermore, having the page_mkwrite() operator causes
> writable_file_mapping_allowed() to fail due to
> vma_needs_dirty_tracking() on the gup flow, which is a pre-requisite for
> enabling P2PDMA with FOLL_LONGTERM use cases.
> 
> Co-developed-by: Logan Gunthorpe <logang@deltatee.com>
> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
> Signed-off-by: Martin Oliveira <martin.oliveira@eideticom.com>

Fine with me, but please s/create/Create/ in the subject to match
history of the file.

Acked-by: Bjorn Helgaas <bhelgaas@google.com>

> ---
>  drivers/pci/p2pdma.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
> index 4f47a13cb500..ac07053abfea 100644
> --- a/drivers/pci/p2pdma.c
> +++ b/drivers/pci/p2pdma.c
> @@ -171,6 +171,7 @@ static struct bin_attribute p2pmem_alloc_attr = {
>  	 * to be very large.
>  	 */
>  	.size = SZ_1T,
> +	.mmap_allocates = true,
>  };
>  
>  static struct attribute *p2pmem_attrs[] = {
> -- 
> 2.34.1
>