From: Christoph Hellwig <hch@infradead.org>
To: Daniel Colascione <dancol@google.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Joel Fernandes <joel@joelfernandes.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
kernel-team@android.com, John Reck <jreck@google.com>,
John Stultz <john.stultz@linaro.org>,
Todd Kjos <tkjos@google.com>,
Greg KH <gregkh@linuxfoundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
"J. Bruce Fields" <bfields@fieldses.org>,
Jeff Layton <jlayton@kernel.org>,
Khalid Aziz <khalid.aziz@oracle.com>,
linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org,
linux-mm <linux-mm@kvack.org>,
Mike Kravetz <mike.kravetz@oracle.com>,
Minchan Kim <minchan@google.com>, Shuah Khan <shuah@kernel.org>
Subject: Re: [PATCH v2 1/2] mm: Add an F_SEAL_FS_WRITE seal to memfd
Date: Wed, 17 Oct 2018 09:19:06 -0700 [thread overview]
Message-ID: <20181017161906.GA5096@infradead.org> (raw)
In-Reply-To: <CAKOZuesr_8vrob-XfEpGmyeKFEhWWXZo4BEC0PixfjT2ibaRZQ@mail.gmail.com>
On Wed, Oct 17, 2018 at 08:44:01AM -0700, Daniel Colascione wrote:
> > Even if no one changes these specific flags we still need a lock due
> > to rmw cycles on the field. For example fadvise can set or clear
> > FMODE_RANDOM. It seems to use file->f_lock for synchronization.
>
> Compare-and-exchange will suffice, right?
Only if all users use the compare and exchange, and right now they
don't.
WARNING: multiple messages have this Message-ID (diff)
From: hch at infradead.org (Christoph Hellwig)
Subject: [PATCH v2 1/2] mm: Add an F_SEAL_FS_WRITE seal to memfd
Date: Wed, 17 Oct 2018 09:19:06 -0700 [thread overview]
Message-ID: <20181017161906.GA5096@infradead.org> (raw)
In-Reply-To: <CAKOZuesr_8vrob-XfEpGmyeKFEhWWXZo4BEC0PixfjT2ibaRZQ@mail.gmail.com>
On Wed, Oct 17, 2018 at 08:44:01AM -0700, Daniel Colascione wrote:
> > Even if no one changes these specific flags we still need a lock due
> > to rmw cycles on the field. For example fadvise can set or clear
> > FMODE_RANDOM. It seems to use file->f_lock for synchronization.
>
> Compare-and-exchange will suffice, right?
Only if all users use the compare and exchange, and right now they
don't.
WARNING: multiple messages have this Message-ID (diff)
From: hch@infradead.org (Christoph Hellwig)
Subject: [PATCH v2 1/2] mm: Add an F_SEAL_FS_WRITE seal to memfd
Date: Wed, 17 Oct 2018 09:19:06 -0700 [thread overview]
Message-ID: <20181017161906.GA5096@infradead.org> (raw)
Message-ID: <20181017161906.OTvyxcdyBCV7gX16wfIiQ2AxpJvzOWZKskSw3Dfb9ZU@z> (raw)
In-Reply-To: <CAKOZuesr_8vrob-XfEpGmyeKFEhWWXZo4BEC0PixfjT2ibaRZQ@mail.gmail.com>
On Wed, Oct 17, 2018@08:44:01AM -0700, Daniel Colascione wrote:
> > Even if no one changes these specific flags we still need a lock due
> > to rmw cycles on the field. For example fadvise can set or clear
> > FMODE_RANDOM. It seems to use file->f_lock for synchronization.
>
> Compare-and-exchange will suffice, right?
Only if all users use the compare and exchange, and right now they
don't.
next prev parent reply other threads:[~2018-10-17 16:19 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-09 22:20 [PATCH v2 1/2] mm: Add an F_SEAL_FS_WRITE seal to memfd Joel Fernandes (Google)
2018-10-09 22:20 ` Joel Fernandes (Google)
2018-10-09 22:20 ` joel
2018-10-09 22:20 ` [PATCH v2 2/2] selftests/memfd: Add tests for F_SEAL_FS_WRITE seal Joel Fernandes (Google)
2018-10-09 22:20 ` Joel Fernandes (Google)
2018-10-09 22:20 ` joel
2018-10-09 22:34 ` Joel Fernandes
2018-10-09 22:34 ` Joel Fernandes
2018-10-09 22:34 ` joel
2018-10-16 21:57 ` [PATCH v2 1/2] mm: Add an F_SEAL_FS_WRITE seal to memfd John Stultz
2018-10-16 21:57 ` John Stultz
2018-10-16 21:57 ` john.stultz
2018-10-17 9:51 ` Christoph Hellwig
2018-10-17 9:51 ` Christoph Hellwig
2018-10-17 9:51 ` hch
2018-10-17 10:39 ` Joel Fernandes
2018-10-17 10:39 ` Joel Fernandes
2018-10-17 10:39 ` joel
2018-10-17 12:08 ` Christoph Hellwig
2018-10-17 12:08 ` Christoph Hellwig
2018-10-17 12:08 ` hch
2018-10-17 15:44 ` Daniel Colascione
2018-10-17 15:44 ` Daniel Colascione
2018-10-17 15:44 ` dancol
2018-10-17 16:19 ` Christoph Hellwig [this message]
2018-10-17 16:19 ` Christoph Hellwig
2018-10-17 16:19 ` hch
2018-10-17 17:45 ` Joel Fernandes
2018-10-17 17:45 ` Joel Fernandes
2018-10-17 17:45 ` joel
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