From: Dave Chinner <david@fromorbit.com>
To: Jan Kara <jack@suse.cz>
Cc: linux-fsdevel@vger.kernel.org, xfs@oss.sgi.com,
linux-ext4@vger.kernel.org, Hugh Dickins <hughd@google.com>,
linux-mm@kvack.org
Subject: Re: Hole punching and mmap races
Date: Fri, 18 May 2012 20:12:10 +1000 [thread overview]
Message-ID: <20120518101210.GX25351@dastard> (raw)
In-Reply-To: <20120517232829.GA31028@quack.suse.cz>
On Fri, May 18, 2012 at 01:28:29AM +0200, Jan Kara wrote:
> On Thu 17-05-12 17:43:08, Dave Chinner wrote:
> > On Wed, May 16, 2012 at 03:04:45PM +0200, Jan Kara wrote:
> > > On Wed 16-05-12 12:14:23, Dave Chinner wrote:
> > IIRC, it's a rare case (that I consider insane, BTW): read from a
> > file with into a buffer that is a mmap()d region of the same file
> > that has not been faulted in yet.....
> With punch hole, the race is less insane - just punching hole in the area
> which is accessed via mmap could race in a bad way AFAICS.
Seems the simple answer to me is to prevent page faults while hole
punching, then....
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
WARNING: multiple messages have this Message-ID (diff)
From: Dave Chinner <david@fromorbit.com>
To: Jan Kara <jack@suse.cz>
Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
linux-ext4@vger.kernel.org, Hugh Dickins <hughd@google.com>,
xfs@oss.sgi.com
Subject: Re: Hole punching and mmap races
Date: Fri, 18 May 2012 20:12:10 +1000 [thread overview]
Message-ID: <20120518101210.GX25351@dastard> (raw)
In-Reply-To: <20120517232829.GA31028@quack.suse.cz>
On Fri, May 18, 2012 at 01:28:29AM +0200, Jan Kara wrote:
> On Thu 17-05-12 17:43:08, Dave Chinner wrote:
> > On Wed, May 16, 2012 at 03:04:45PM +0200, Jan Kara wrote:
> > > On Wed 16-05-12 12:14:23, Dave Chinner wrote:
> > IIRC, it's a rare case (that I consider insane, BTW): read from a
> > file with into a buffer that is a mmap()d region of the same file
> > that has not been faulted in yet.....
> With punch hole, the race is less insane - just punching hole in the area
> which is accessed via mmap could race in a bad way AFAICS.
Seems the simple answer to me is to prevent page faults while hole
punching, then....
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs
WARNING: multiple messages have this Message-ID (diff)
From: Dave Chinner <david@fromorbit.com>
To: Jan Kara <jack@suse.cz>
Cc: linux-fsdevel@vger.kernel.org, xfs@oss.sgi.com,
linux-ext4@vger.kernel.org, Hugh Dickins <hughd@google.com>,
linux-mm@kvack.org
Subject: Re: Hole punching and mmap races
Date: Fri, 18 May 2012 20:12:10 +1000 [thread overview]
Message-ID: <20120518101210.GX25351@dastard> (raw)
In-Reply-To: <20120517232829.GA31028@quack.suse.cz>
On Fri, May 18, 2012 at 01:28:29AM +0200, Jan Kara wrote:
> On Thu 17-05-12 17:43:08, Dave Chinner wrote:
> > On Wed, May 16, 2012 at 03:04:45PM +0200, Jan Kara wrote:
> > > On Wed 16-05-12 12:14:23, Dave Chinner wrote:
> > IIRC, it's a rare case (that I consider insane, BTW): read from a
> > file with into a buffer that is a mmap()d region of the same file
> > that has not been faulted in yet.....
> With punch hole, the race is less insane - just punching hole in the area
> which is accessed via mmap could race in a bad way AFAICS.
Seems the simple answer to me is to prevent page faults while hole
punching, then....
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
--
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next prev parent reply other threads:[~2012-05-18 10:12 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-15 22:48 Hole punching and mmap races Jan Kara
2012-05-15 22:48 ` Jan Kara
2012-05-15 22:48 ` Jan Kara
2012-05-16 2:14 ` Dave Chinner
2012-05-16 2:14 ` Dave Chinner
2012-05-16 2:14 ` Dave Chinner
2012-05-16 13:04 ` Jan Kara
2012-05-16 13:04 ` Jan Kara
2012-05-16 13:04 ` Jan Kara
2012-05-17 7:43 ` Dave Chinner
2012-05-17 7:43 ` Dave Chinner
2012-05-17 7:43 ` Dave Chinner
2012-05-17 23:28 ` Jan Kara
2012-05-17 23:28 ` Jan Kara
2012-05-17 23:28 ` Jan Kara
2012-05-18 10:12 ` Dave Chinner [this message]
2012-05-18 10:12 ` Dave Chinner
2012-05-18 10:12 ` Dave Chinner
2012-05-18 13:32 ` Jan Kara
2012-05-18 13:32 ` Jan Kara
2012-05-18 13:32 ` Jan Kara
2012-05-19 1:40 ` Dave Chinner
2012-05-19 1:40 ` Dave Chinner
2012-05-24 12:35 ` Jan Kara
2012-05-24 12:35 ` Jan Kara
2012-05-24 12:35 ` Jan Kara
2012-06-05 5:51 ` Dave Chinner
2012-06-05 5:51 ` Dave Chinner
2012-06-05 5:51 ` Dave Chinner
2012-06-05 6:22 ` Marco Stornelli
2012-06-05 6:22 ` Marco Stornelli
2012-06-05 6:22 ` Marco Stornelli
2012-06-05 23:15 ` Jan Kara
2012-06-05 23:15 ` Jan Kara
2012-06-05 23:15 ` Jan Kara
2012-06-06 0:06 ` Dave Chinner
2012-06-06 0:06 ` Dave Chinner
2012-06-06 0:06 ` Dave Chinner
2012-06-06 9:58 ` Jan Kara
2012-06-06 9:58 ` Jan Kara
2012-06-06 9:58 ` Jan Kara
2012-06-06 13:36 ` Dave Chinner
2012-06-06 13:36 ` Dave Chinner
2012-06-06 13:36 ` Dave Chinner
2012-06-07 21:58 ` Jan Kara
2012-06-07 21:58 ` Jan Kara
2012-06-07 21:58 ` Jan Kara
2012-06-08 0:57 ` Dave Chinner
2012-06-08 0:57 ` Dave Chinner
2012-06-08 21:36 ` Jan Kara
2012-06-08 21:36 ` Jan Kara
2012-06-08 23:06 ` Dave Chinner
2012-06-08 23:06 ` Dave Chinner
2012-06-12 8:56 ` Jan Kara
2012-06-12 8:56 ` Jan Kara
2012-06-12 8:56 ` Jan Kara
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