From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 24 Aug 2001 14:07:49 +0100 From: "Stephen C. Tweedie" Subject: Re: SWAP_MAP_MAX: How? Message-ID: <20010824140749.C4389@redhat.com> References: <20010824121951.A4389@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: ; from hugh@veritas.com on Fri, Aug 24, 2001 at 01:42:59PM +0100 Sender: owner-linux-mm@kvack.org Return-Path: To: Hugh Dickins Cc: "Stephen C. Tweedie" , Andrea Arcangeli , Ben LaHaise , Marcelo Tosatti , Rik van Riel , linux-mm@kvack.org List-ID: Hi, On Fri, Aug 24, 2001 at 01:42:59PM +0100, Hugh Dickins wrote: > Doesn't it need an anonymous page mapped multiple (e.g. 256) times > into multiple (e.g. 256) mms to reach the limit? That would do it, yes. > And there's an obvious > way that can happen, by multiply attaching a piece of IPC Shared Memory, > and multiply forking. But in that case it's the shared memory object > which gets the large number of references, and the swap counts stay 1. Indeed --- sysV shm swapping is eccentric. :-) There _was_ once a way to do this --- mmap()ing another process's /proc/*/mem would allow you to get a swap page mapped into memory multiple times, but we removed support for that way back in pre-2.2 days. I don't think we allow that any more, unless it's been reenabled again. Cheers, Stephen -- 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/