Subject: Re: [PATCH][RFC] add MAP_UNLOCKED mmap flag
From: Peter Zijlstra <peterz@infradead.org>
To: Gleb Natapov <gleb@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>, linux-mm@kvack.org,
       linux-kernel@vger.kernel.org, linux-api@vger.kernel.org
In-Reply-To: <20091006121603.GK9832@redhat.com>
References: <20091006190938.126F.A69D9226@jp.fujitsu.com>
	 <20091006102136.GH9832@redhat.com>
	 <20091006192454.1272.A69D9226@jp.fujitsu.com>
	 <20091006103300.GI9832@redhat.com>
	 <2f11576a0910060510y401c1d5ax6f17135478d22899@mail.gmail.com>
	 <20091006121603.GK9832@redhat.com>
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Date: Tue, 06 Oct 2009 15:50:03 +0200
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On Tue, 2009-10-06 at 14:16 +0200, Gleb Natapov wrote:
> > No, I only think your case doesn't fit MC_FUTURE.
> > I haven't find any real benefit in this patch.

> I did. It allows me to achieve something I can't now. Steps you provide
> just don't fit my needs. I need all memory areas (current and feature) to be
> locked except one. Very big one. You propose to lock memory at some
> arbitrary point and from that point on all newly mapped memory areas will
> be unlocked. Don't you see it is different?

While true, it does demonstrates very sloppy programming. The proper fix
is to rework qemu to mlock what is needed.

I'm not sure encouraging mlockall() usage is a good thing. When using
resource locks one had better know what he's doing. mlockall() doesn't
promote caution.

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