From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 15 Mar 2006 17:06:33 -0600 From: Marcelo Tosatti Subject: Re: page migration: Fail with error if swap not setup Message-ID: <20060315230633.GA14825@dmt.cnet> References: <1142434053.5198.1.camel@localhost.localdomain> <20060315204742.GB12432@dmt.cnet> <20060315213904.GA13771@dmt.cnet> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: Lee Schermerhorn , linux-mm@kvack.org, nickpiggin@yahoo.com.au, akpm@osdl.org List-ID: On Wed, Mar 15, 2006 at 11:00:31AM -0800, Christoph Lameter wrote: > On Wed, 15 Mar 2006, Marcelo Tosatti wrote: > > > > That does not answer the question if VM_LOCKED pages should be > > > migratable. We all agree that they should not show up on swap. > > > > I guess you missed the first part of the man page: > > > > All pages which contain a part of the specified memory range are > > guaranteed be resident in RAM when the mlock system call returns > > successfully and they are guaranteed to stay in RAM until the pages are > > unlocked by munlock or munlockall, until the pages are unmapped via > > munmap, or until the process terminates or starts another program with > > exec. Child processes do not inherit page locks across a fork. > > > > That is, mlock() only guarantees that pages are kept in RAM and not > > swapped. It does seem to refer to physical placing of pages. > > If VM_LOCKED is not pinning memory then how does one pin memory? There are > likely applications / drivers that require memory not to move. Increase > pagecount? Err, I meant that mlock() does _not_ refer to physical placing of pages, it only refers to guaranteed availability of page in RAM (as can be read in the man page). Now drivers using VM_LOCKED is another history... In the end my comments haven't been useful at all, oh well. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org