Subject: Re: [PATCH V3 3/5] mm: mlock: Introduce VM_LOCKONFAULT and add mlock flags to enable it

From: Jonathan Corbet <[email-masked]>
Date: Wed, 8 Jul 2015 13:23:51 -0600

On Tue,  7 Jul 2015 13:03:41 -0400
Eric B Munson <[email-masked]> wrote:

> This patch introduces the ability to request that pages are not
> pre-faulted, but are placed on the unevictable LRU when they are finally
> faulted in.  This can be done area at a time via the
> mlock2(MLOCK_ONFAULT) or the mlockall(MCL_ONFAULT) system calls.  These
> calls can be undone via munlock2(MLOCK_ONFAULT) or
> munlockall2(MCL_ONFAULT).

Quick, possibly dumb question: I've been beating my head against these for
a little bit, and I can't figure out what's supposed to happen in this
case:

	mlock2(addr, len, MLOCK_ONFAULT);
	munlock2(addr, len, MLOCK_LOCKED);

It looks to me like it will clear VM_LOCKED without actually unlocking any
pages.  Is that the intended result?

Thanks,

jon