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From: Andrew Morton <akpm@linux-foundation.org>
To: "Joel Fernandes (Google)" <joel@joelfernandes.org>
Cc: linux-kernel@vger.kernel.org, jreck@google.com,
	john.stultz@linaro.org, tkjos@google.com,
	gregkh@linuxfoundation.org, hch@infradead.org,
	"Al Viro" <viro@zeniv.linux.org.uk>,
	dancol@google.com, "J. Bruce Fields" <bfields@fieldses.org>,
	"Jeff Layton" <jlayton@kernel.org>,
	"Khalid Aziz" <khalid.aziz@oracle.com>,
	"Lei Yang" <Lei.Yang@windriver.com>,
	linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org,
	linux-mm@kvack.org,
	"Marc-André Lureau" <marcandre.lureau@redhat.com>,
	"Mike Kravetz" <mike.kravetz@oracle.com>,
	minchan@kernel.org, "Shuah Khan" <shuah@kernel.org>,
	valdis.kletnieks@vt.edu
Subject: Re: [PATCH v3 resend 1/2] mm: Add an F_SEAL_FUTURE_WRITE seal to memfd
Date: Fri, 9 Nov 2018 12:36:34 -0800
Message-ID: <20181109123634.6fe7467bb9237851250c9c56@linux-foundation.org> (raw)
In-Reply-To: <20181108041537.39694-1-joel@joelfernandes.org>

On Wed,  7 Nov 2018 20:15:36 -0800 "Joel Fernandes (Google)" <joel@joelfernandes.org> wrote:

> Android uses ashmem for sharing memory regions. We are looking forward
> to migrating all usecases of ashmem to memfd so that we can possibly
> remove the ashmem driver in the future from staging while also
> benefiting from using memfd and contributing to it. Note staging drivers
> are also not ABI and generally can be removed at anytime.
> 
> One of the main usecases Android has is the ability to create a region
> and mmap it as writeable, then add protection against making any
> "future" writes while keeping the existing already mmap'ed
> writeable-region active.  This allows us to implement a usecase where
> receivers of the shared memory buffer can get a read-only view, while
> the sender continues to write to the buffer.
> See CursorWindow documentation in Android for more details:
> https://developer.android.com/reference/android/database/CursorWindow

It appears that the memfd_create and fcntl manpages will require
updating.  Please attend to this at the appropriate time?

Actually, it would help the review process if those updates were
available now.


  parent reply index

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-08  4:15 Joel Fernandes (Google)
2018-11-08  4:15 ` [PATCH v3 resend 2/2] selftests/memfd: Add tests for F_SEAL_FUTURE_WRITE seal Joel Fernandes (Google)
2018-11-09  8:49 ` [PATCH v3 resend 1/2] mm: Add an F_SEAL_FUTURE_WRITE seal to memfd Joel Fernandes
2018-11-09 20:36 ` Andrew Morton [this message]
2018-11-10  3:54   ` Joel Fernandes
2018-11-09 21:06 ` Jann Horn
2018-11-09 21:19   ` Jann Horn
2018-11-10  3:20     ` Joel Fernandes
2018-11-10  6:05       ` Andy Lutomirski
2018-11-10 18:24         ` Joel Fernandes
2018-11-10 18:45           ` Daniel Colascione
2018-11-10 19:11             ` Daniel Colascione
2018-11-10 19:55               ` Andy Lutomirski
2018-11-10 22:09               ` Joel Fernandes
2018-11-10 22:18                 ` Andy Lutomirski
2018-11-11  2:38                   ` Joel Fernandes
2018-11-11  3:40                     ` Andy Lutomirski
2018-11-11  4:01                       ` Joel Fernandes
2018-11-11  8:09                       ` Joel Fernandes
2018-11-11  8:30                         ` Daniel Colascione
2018-11-11 15:14                           ` Andy Lutomirski
2018-11-11 17:36                             ` Joel Fernandes
     [not found]       ` <CAKOZuethC7+YrRyyGciUCfhSSa9cCcAFJ8g_qEw9uh3TBbyOcg@mail.gmail.com>
2018-11-10 17:10         ` Joel Fernandes
2018-11-09 21:40   ` Andy Lutomirski
2018-11-09 20:02     ` Michael Tirado
2018-11-10  1:49       ` Joel Fernandes
2018-11-09 22:20   ` Daniel Colascione
2018-11-09 22:37     ` Andy Lutomirski
2018-11-09 22:42       ` Daniel Colascione
2018-11-09 23:14         ` Andy Lutomirski
2018-11-10  1:36           ` Joel Fernandes
2018-11-09 23:46   ` Joel Fernandes

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