From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with SMTP id 422006B003D for ; Sun, 3 May 2009 05:06:01 -0400 (EDT) Message-ID: <49FD5E96.6060301@redhat.com> Date: Sun, 03 May 2009 12:06:30 +0300 From: Izik Eidus MIME-Version: 1.0 Subject: Re: [PATCH 1/6] ksm: limiting the num of mem regions user can register per fd. References: <1241302572-4366-1-git-send-email-ieidus@redhat.com> <1241302572-4366-2-git-send-email-ieidus@redhat.com> <20090502220829.392b7ff9@riellaptop.surriel.com> In-Reply-To: <20090502220829.392b7ff9@riellaptop.surriel.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Rik van Riel Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, aarcange@redhat.com, chrisw@redhat.com, alan@lxorguk.ukuu.org.uk, device@lanana.org, linux-mm@kvack.org, hugh@veritas.com, nickpiggin@yahoo.com.au List-ID: Rik van Riel wrote: > On Sun, 3 May 2009 01:16:07 +0300 > Izik Eidus wrote: > > >> Right now user can open /dev/ksm fd and register unlimited number of >> regions, such behavior may allocate unlimited amount of kernel memory >> and get the whole host into out of memory situation. >> > > How many times can a process open /dev/ksm? > > If a process can open /dev/ksm a thousand times and then > register 1000 regions through each file descriptor, this > patch does not help all that much... > > The idea is that the limitation is now on the maximum file descriptors user can open. So for each such file descriptor user can open 1024 structures that are just few bytes each. The whole propose of this patch is to avoid while (1) { IOCTL(REGISTER_MEMORY_REGION) } and oom the host. -- 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/ . Don't email: email@kvack.org