From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from web3.hq.eso.org (web3.hq.eso.org [134.171.7.4]) by kvack.org (8.8.7/8.8.7) with ESMTP id EAA24771 for ; Mon, 17 Aug 1998 04:47:00 -0400 Received: from localhost (ndevilla@localhost) by opus3.hq.eso.org (8.8.5/eso_cl_6.0) with SMTP id KAA27333 for ; Mon, 17 Aug 1998 10:46:25 +0200 (MET DST) Date: Mon, 17 Aug 1998 10:46:24 +0200 (MET DST) From: Nicolas Devillard Subject: memory overcommitment Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: linux-mm@kvack.org List-ID: Dear all: I can allocate up to 2 gigs of memory on a Linux box with 256 megs of actual RAM + swap. Having browsed through pages and pages of linux-kernel mailing-lists archives, I found out a thread discussing that with the usual pros and cons, but could not find anything done about it. Ah, and I know the standard answer: ulimit or limit would do the job, but they do not apply system-wide. The usual story of over-commitment compares memory allocation to airplane companies, but in this case something goes wrong: the kernel actually knows that it has only 256 megs, why does it commit itself to promise more than 8 times this amount to any normal user requesting it?? A company selling 100 tickets for a 12-seat plane would have serious problems I guess. It is Ok to overbook, but what are you doing exactly when all passengers show up at the counter, especially when you have overbooked by a factor 8 or so? In this case, I found out that once I start touching the 2 generously allocated gigs of memory, RAM goes away, then swap, then daemons start dying one by one and the machine freezes to the point of unusability. More than a single memory allocation problem or policy, it is a serious threat to security, because it allows to kill dameons for any user. Anything done about it? Some references I may have missed about this point? Someone working on it? An easy quickfix maybe?? Thanks for helping, Nicolas -- This is a majordomo managed list. To unsubscribe, send a message with the body 'unsubscribe linux-mm me@address' to: majordomo@kvack.org