From: Greg Kroah-Hartman <gregkh@linuxfoundation.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>, 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 1/6] kernfs: create vm_operations_struct without page_mkwrite()
Date: Thu, 6 Jun 2024 22:54:06 +0200 [thread overview]
Message-ID: <2024060658-ember-unblessed-4c74@gregkh> (raw)
In-Reply-To: <20240605192934.742369-2-martin.oliveira@eideticom.com>
On Wed, Jun 05, 2024 at 01:29:29PM -0600, Martin Oliveira wrote:
> The standard kernfs vm_ops installs a page_mkwrite() operator which
> modifies the file update time on write.
>
> This not always required (or makes sense), such as in the P2PDMA, which
> uses the sysfs file as an allocator from userspace.
That's not a good idea, please don't do that. sysfs binary files are
"pass through", why would you want to use this as an allocator?
> 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 over RDMA.
>
> Fix this by adding a new boolean on kernfs_ops to differentiate between
> the different behaviours.
This isn't going to work well.
What exactly are you wanting to do in sysfs that you feel this is
required?
thanks,
greg k-h
next prev parent reply other threads:[~2024-06-06 20:54 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-06-05 19:29 [PATCH 0/6] Enable P2PDMA in Userspace RDMA Martin Oliveira
2024-06-05 19:29 ` [PATCH 1/6] kernfs: create vm_operations_struct without page_mkwrite() Martin Oliveira
2024-06-05 21:43 ` Bjorn Helgaas
2024-06-06 20:54 ` Greg Kroah-Hartman [this message]
2024-06-06 21:32 ` Logan Gunthorpe
2024-06-07 5:03 ` Christoph Hellwig
2024-06-07 16:16 ` Logan Gunthorpe
2024-06-07 19:18 ` Greg Kroah-Hartman
2024-06-05 19:29 ` [PATCH 2/6] sysfs: add mmap_allocates parameter to struct bin_attribute Martin Oliveira
2024-06-05 19:29 ` [PATCH 3/6] PCI/P2PDMA: create VMA without page_mkwrite() operator Martin Oliveira
2024-06-05 21:45 ` Bjorn Helgaas
2024-06-05 19:29 ` [PATCH 4/6] mm/gup: handle ZONE_DEVICE pages in folio_fast_pin_allowed() Martin Oliveira
2024-06-05 19:29 ` [PATCH 5/6] mm/gup: allow FOLL_LONGTERM & FOLL_PCI_P2PDMA Martin Oliveira
2024-06-05 19:29 ` [PATCH 6/6] RDMA/umem: add support for P2P RDMA Martin Oliveira
2024-06-10 12:11 ` Jason Gunthorpe
2024-06-06 8:53 ` [PATCH 0/6] Enable P2PDMA in Userspace RDMA Zhu Yanjun
2024-06-06 21:32 ` Martin Oliveira
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