From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758840Ab2C2CIg (ORCPT ); Wed, 28 Mar 2012 22:08:36 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58039 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758641Ab2C2CIb (ORCPT ); Wed, 28 Mar 2012 22:08:31 -0400 Date: Wed, 28 Mar 2012 22:08:20 -0400 From: Dave Jones To: Andrew Morton Cc: Joe Perches , Dave Chinner , viro@zeniv.linux.org.uk, Linux Kernel , David Rientjes Subject: Re: suppress page allocation failure warnings from sys_listxattr Message-ID: <20120329020820.GB22697@redhat.com> Mail-Followup-To: Dave Jones , Andrew Morton , Joe Perches , Dave Chinner , viro@zeniv.linux.org.uk, Linux Kernel , David Rientjes References: <20120327155149.d41a235b.akpm@linux-foundation.org> <20120328001550.GA3077@redhat.com> <20120328043951.GA32741@dastard> <20120328164720.d1aea752.akpm@linux-foundation.org> <20120329005442.GB16008@redhat.com> <20120328181023.274401d1.akpm@linux-foundation.org> <1332984523.30775.12.camel@joe2Laptop> <20120328184602.e6b11a37.akpm@linux-foundation.org> <20120329015059.GA22697@redhat.com> <20120328190211.4ac8a653.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120328190211.4ac8a653.akpm@linux-foundation.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 28, 2012 at 07:02:11PM -0700, Andrew Morton wrote: > > Also, what happens if something allocates > > and sits on a bunch of vmalloc'd memory ? would we start seeing oom kills ? > > vmalloc() would fail. Ok, that's a pretty boring failure mode, so not a big deal probably. > > (thinking of the context of my fuzzing tool where a bunch of instances could > > feasibly call these syscalls and not sit on huge amounts per thread, but > > collectively... I'm wondering if it could be provoked into killing > > processes I don't own) > > umm, if you wanted to deliberately trigger a vmalloc() failure then I > guess a good approach would be to locate a vmalloc() site which can > persist beyond the syscall (modprobe is a good one!) then exercise it > in a way so that there are no N-byte holes left in the arena, then > trigger an N-byte vmalloc(). Well modprobe is root-only, so that's not so bad. But it looks like key_add (see other thread from this evening) and probably others can be called as a user and gobble up vmalloc space. omnomnom. Dave