Re: [PATCH 1/7] mm/gup: remove unused vmas parameter from get_user_pages()

From: Jason Gunthorpe <jgg@nvidia.com>
To: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: kvm@vger.kernel.org, David Hildenbrand <david@redhat.com>,
	dri-devel@lists.freedesktop.org, linux-mm@kvack.org,
	amd-gfx@lists.freedesktop.org, "H . Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, Matthew Wilcox <willy@infradead.org>,
	Ingo Molnar <mingo@redhat.com>, Arnd Bergmann <arnd@arndb.de>,
	Borislav Petkov <bp@alien8.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-sgx@vger.kernel.org,
	Dimitri Sivanich <dimitri.sivanich@hpe.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Xinhui Pan <Xinhui.Pan@amd.com>,
	linux-kernel@vger.kernel.org, Jarkko Sakkinen <jarkko@kernel.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 1/7] mm/gup: remove unused vmas parameter from get_user_pages()
Date: Mon, 17 Apr 2023 10:01:54 -0300	[thread overview]
Message-ID: <ZD1DQrSLlMn4CUZX@nvidia.com> (raw)
In-Reply-To: <d40cb239d0ca01e51f7fc2a276398e8f4dedf9ff.1681508038.git.lstoakes@gmail.com>

On Sat, Apr 15, 2023 at 12:27:13AM +0100, Lorenzo Stoakes wrote:
> No invocation of get_user_pages() uses the vmas parameter, so remove
> it.
> 
> The GUP API is confusing and caveated. Recent changes have done much to
> improve that, however there is more we can do. Exporting vmas is a prime
> target as the caller has to be extremely careful to preclude their use
> after the mmap_lock has expired or otherwise be left with dangling
> pointers.
> 
> Removing the vmas parameter focuses the GUP functions upon their primary
> purpose - pinning (and outputting) pages as well as performing the actions
> implied by the input flags.
> 
> This is part of a patch series aiming to remove the vmas parameter
> altogether.
> 
> Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
> Suggested-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
>  arch/x86/kernel/cpu/sgx/ioctl.c     | 2 +-
>  drivers/gpu/drm/radeon/radeon_ttm.c | 2 +-
>  drivers/misc/sgi-gru/grufault.c     | 2 +-
>  include/linux/mm.h                  | 3 +--
>  mm/gup.c                            | 9 +++------
>  mm/gup_test.c                       | 5 ++---
>  virt/kvm/kvm_main.c                 | 4 ++--
>  7 files changed, 11 insertions(+), 16 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason