From owner-freebsd-current@FreeBSD.ORG Wed Aug 15 15:52:26 2012 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id D6013106566B; Wed, 15 Aug 2012 15:52:26 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from bigwig.baldwin.cx (bigknife-pt.tunnel.tserv9.chi1.ipv6.he.net [IPv6:2001:470:1f10:75::2]) by mx1.freebsd.org (Postfix) with ESMTP id A98058FC12; Wed, 15 Aug 2012 15:52:26 +0000 (UTC) Received: from jhbbsd.localnet (unknown [209.249.190.124]) by bigwig.baldwin.cx (Postfix) with ESMTPSA id 1318BB99C; Wed, 15 Aug 2012 11:52:26 -0400 (EDT) From: John Baldwin To: Sergey Kandaurov Date: Wed, 15 Aug 2012 11:21:34 -0400 User-Agent: KMail/1.13.5 (FreeBSD/8.2-CBSD-20110714-p17; KDE/4.5.5; amd64; ; ) References: <7BEE3948-EE35-48C2-B4B1-25E34087A4C4@lists.zabbadoz.net> In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201208151121.34815.jhb@freebsd.org> X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.2.7 (bigwig.baldwin.cx); Wed, 15 Aug 2012 11:52:26 -0400 (EDT) Cc: "Bjoern A. Zeeb" , freebsd-current FreeBSD , des@freebsd.org Subject: Re: swp_pager_meta_build DoS printf X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 15 Aug 2012 15:52:26 -0000 On Monday, August 13, 2012 1:49:38 am Sergey Kandaurov wrote: > On 2 July 2012 20:31, Bjoern A. Zeeb wrote: > > > > On 2. Jul 2012, at 14:36 , John Baldwin wrote: > > > >> On Sunday, July 01, 2012 8:23:31 am Bjoern A. Zeeb wrote: > >>> Hey, > >>> > >>> hitting this printf in swp_pager_meta_build() > >>> > >>> if (uma_zone_exhausted(swap_zone)) { > >>> printf("swap zone exhausted, increase kern.maxswzone\n"); > >>> vm_pageout_oom(VM_OOM_SWAPZ); > >>> pause("swzonex", 10); > >>> } else > >>> > >>> seems to be an effective way to put the machine into a state of no recovery > >>> unless the memory situation would be able to clear itself. Not that it wouldn't > >>> otherwise be any better but in addition having a couple of tenthousands of these > >>> going to console as well is really not helpful to try to do anything either. Can > >>> we make it a log() call or something? > >>> > >>> /bz > >>> > >>> PS: I am not sure as I have seen it on someone else's machines and it's > >>> probably been ZFS that caused it. I unfortunately neither had a way to > >>> get back in or break to a kernel debugger, so information is sparse. > >> > >> This used to be a silent deadlock before I added the printf() and the call to > >> OOM. :-P Do you just want to ratelimit the printf? We have an API to ratelimit > >> printf's already. > > > > Ratelimit would be fine; I was writing that on the wrong time of the wrong day to > > just get it out; could you do that? > > Hi, looks like the discussion was abandoned. > What about this patch? It enables to ratelimit the printf. > Also, are the new variables put in the right places from the style pov? I think DES has a newer variant of this now? -- John Baldwin