From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <3D88D9DE.2FB9A23D@digeo.com> Date: Wed, 18 Sep 2002 12:54:06 -0700 From: Andrew Morton MIME-Version: 1.0 Subject: Re: [PATCH] recognize MAP_LOCKED in mmap() call References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Mark_H_Johnson@raytheon.com Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, owner-linux-mm@kvack.org List-ID: Mark_H_Johnson@raytheon.com wrote: > > Andrew Morton wrote: > >(SuS really only anticipates that mmap needs to look at prior mlocks > >in force against the address range. It also says > > > > Process memory locking does apply to shared memory regions, > > > >and we don't do that either. I think we should; can't see why SuS > >requires this.) > > Let me make sure I read what you said correctly. Does this mean that Linux > 2.4 (or 2.5) kernels do not lock shared memory regions if a process uses > mlockall? Linux does lock these regions. SuS seems to imply that we shouldn't. But we should. > If not, that is *really bad* for our real time applications. We don't want > to take a page fault while running some 80hz task, just because some > non-real time application tried to use what little physical memory we allow > for the kernel and all other applications. > > I asked a related question about a week ago on linux-mm and didn't get a > response. Basically, I was concerned that top did not show RSS == Size when > mlockall(MCL_CURRENT|MCL_FUTURE) was called. Could this explain the > difference or is there something else that I'm missing here? > That mlockall should have faulted everything in. It could be an accounting bug, or it could be a bug. That's not an aspect which gets tested a lot. I'll take a look. -- 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/