From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: ARM cacheflush syscall with range that spans multiple vma
Date: Mon, 10 Jun 2013 10:09:47 +0100 [thread overview]
Message-ID: <20130610090947.GC6580@mudshark.cambridge.arm.com> (raw)
In-Reply-To: <20130610085948.GP18614@n2100.arm.linux.org.uk>
On Mon, Jun 10, 2013 at 09:59:48AM +0100, Russell King - ARM Linux wrote:
> On Sun, Jun 09, 2013 at 05:05:24PM -0700, John Reiser wrote:
> > Why does the ARM cacheflush syscall stop after the lowest vma
> > which intersects the user-requested range? The range could
> > span more than one vma having contiguous addresses, such as
> > two files MAP_SHARED into adjacent pages; or even a region
> > that contains holes (pages not present.)
>
> Because you're not supposed to use it on large ranges because it's
> an expensive operation.
I posted some patches to address this recently. Obviously it's still
expensive, but it makes the syscall restartable so that you can't DoS the
system.
git://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git cacheflush
There's WIP code there for a new iovec-based syscall too.
Will
next prev parent reply other threads:[~2013-06-10 9:09 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-10 0:05 ARM cacheflush syscall with range that spans multiple vma John Reiser
2013-06-10 8:59 ` Russell King - ARM Linux
2013-06-10 9:09 ` Will Deacon [this message]
2013-06-10 20:16 ` John Reiser
2013-06-10 23:42 ` Russell King - ARM Linux
2013-06-11 10:11 ` Will Deacon
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