From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751356Ab0J1EJl (ORCPT ); Thu, 28 Oct 2010 00:09:41 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:42241 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750773Ab0J1EJk (ORCPT ); Thu, 28 Oct 2010 00:09:40 -0400 Date: Wed, 27 Oct 2010 21:08:55 -0700 From: Andrew Morton To: Davide Libenzi Cc: Robin Holt , "Eric W. Biederman" , Linux Kernel Mailing List , Pekka Enberg Subject: Re: [Patch] Convert max_user_watches to long. Message-Id: <20101027210855.11c5a564.akpm@linux-foundation.org> In-Reply-To: References: <20101027190914.146006767@gulag1.americas.sgi.com> <20101027190921.059806977@gulag1.americas.sgi.com> <20101027164502.d6e2068d.akpm@linux-foundation.org> X-Mailer: Sylpheed 2.7.1 (GTK+ 2.18.9; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 27 Oct 2010 19:03:55 -0700 (PDT) Davide Libenzi wrote: > > Is the expected use case one-watch-per-user-per-fd? If so, then > > perhaps the max number of user_watches should have some realtionship > > with the max number of fds? > > Yes, the expected case is one watch per fd, but the reason the watch limit > went in in the first place, was because of DoS potential of someone not > playing nicely. Sometimes DoS's are accidental. It only takes 25 people to be running the same buggy (eg, slowly-leaky) app (or shared lib) at the same time... There are surely plenty of ways of that sort of thing happening, of course. Not that this fact actually improves anything.