From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with ESMTP id 87B558D0040 for ; Mon, 28 Mar 2011 19:46:49 -0400 (EDT) Received: from hpaq1.eem.corp.google.com (hpaq1.eem.corp.google.com [172.25.149.1]) by smtp-out.google.com with ESMTP id p2SNklwE008952 for ; Mon, 28 Mar 2011 16:46:47 -0700 Received: from gyf3 (gyf3.prod.google.com [10.243.50.67]) by hpaq1.eem.corp.google.com with ESMTP id p2SNkhaZ022316 (version=TLSv1/SSLv3 cipher=RC4-SHA bits=128 verify=NOT) for ; Mon, 28 Mar 2011 16:46:45 -0700 Received: by gyf3 with SMTP id 3so1575201gyf.31 for ; Mon, 28 Mar 2011 16:46:42 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <20110324182240.5fe56de2.kamezawa.hiroyu@jp.fujitsu.com> <20110324105222.GA2625@barrios-desktop> <20110325090411.56c5e5b2.kamezawa.hiroyu@jp.fujitsu.com> <20110325115453.82a9736d.kamezawa.hiroyu@jp.fujitsu.com> <20110326023452.GA8140@google.com> Date: Mon, 28 Mar 2011 16:46:42 -0700 Message-ID: Subject: Re: [PATCH 0/4] forkbomb killer From: Michel Lespinasse Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: Hiroyuki Kamezawa Cc: Minchan Kim , KAMEZAWA Hiroyuki , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "rientjes@google.com" , Andrey Vagin , KOSAKI Motohiro , Hugh Dickins , Johannes Weiner , Rik van Riel On Sat, Mar 26, 2011 at 1:48 AM, Hiroyuki Kamezawa wrote: > 2011/3/26 Michel Lespinasse : >> I haven't heard of fork bombs being an issue for us (and it's not been >> for me on my desktop, either). >> >> Also, I want to point out that there is a classical userspace solution >> for this, as implemented by killall5 for example. One can do >> kill(-1, SIGSTOP) to stop all processes that they can send >> signals to (except for init and itself). Target processes >> can never catch or ignore the SIGSTOP. This stops the fork bomb >> from causing further damage. Then, one can look at the process >> tree and do whatever is appropriate - including killing by uid, >> by cgroup or whatever policies one wants to implement in userspace. >> Finally, the remaining processes can be restarted using SIGCONT. >> > > Can that solution work even under OOM situation without new login/command= s ? > Please show us your solution, how to avoid Andrey's Bomb =A0with your way= . > Then, we can add Documentation, at least. Or you can show us your tool. To be clear, I don't have a full solution. I just think that the problem is approachable from userspace by freezing processes and then sorting them out. The killall5 utility is an example of that, though you would possibly want to add more smarts to it. If we want to include a kernel solution, I do like the simplicity of Minchan's proposal, too. But, I don't have a strong opinion on this matter, so feel free to ignore me if this is not useful feedback. --=20 Michel "Walken" Lespinasse A program is never fully debugged until the last user dies. -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org