From owner-freebsd-net@FreeBSD.ORG Fri Nov 21 17:40:32 2014 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 838816D0; Fri, 21 Nov 2014 17:40:32 +0000 (UTC) Received: from mail-wg0-x22d.google.com (mail-wg0-x22d.google.com [IPv6:2a00:1450:400c:c00::22d]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 0FE2212; Fri, 21 Nov 2014 17:40:32 +0000 (UTC) Received: by mail-wg0-f45.google.com with SMTP id b13so7228730wgh.18 for ; Fri, 21 Nov 2014 09:40:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:cc:content-type:content-transfer-encoding; bh=aq4Ls6SifHN5qltdps2kYF4R97tTeQt6JfZK1rSYKWU=; b=EkLv+OlPfp+B18HyMoXI/dIAUHKRzzdSeIvnZQrBKi9UbQnXiHpftcUy5AJWXzk+8R +gEAYb0KYcQVD4/2PUw/0X9O0CDKfKeXr3tRLbpYlfclA8lVL2nk2CsACKxjo2+xlut0 Z8kXF2Xg7AUO8iYuo/0rEcKjM11IgHbgDgmKbhEcBfwqNVePHS9gi6H+ORXk9ohjLFOd wmgGEtqQGSrQ95AERmodMn0qaZHasWr2FrRozicANI1QK4khEPw72TE6M7Zen15qmy+g nuRn6hQp+NL6J5AIkrP18FZ7LCr5Rz8aRfihwxL+bUxbM0OjWDMwzc6CvoKE+3Dh50yE U7Vg== MIME-Version: 1.0 X-Received: by 10.194.80.100 with SMTP id q4mr9886754wjx.15.1416591627754; Fri, 21 Nov 2014 09:40:27 -0800 (PST) Sender: adrian.chadd@gmail.com Received: by 10.216.106.136 with HTTP; Fri, 21 Nov 2014 09:40:27 -0800 (PST) In-Reply-To: <072B7B0F-4DE3-4D37-BC94-1DEA38CF3B12@FreeBSD.org> References: <20141121002937.4f82daea@x23> <9300CB5F-6140-4C49-B026-EB69B0E8B37E@FreeBSD.org> <20141121120201.6c77ea5b@x23> <20141121162042.449b22dc@x23> <072B7B0F-4DE3-4D37-BC94-1DEA38CF3B12@FreeBSD.org> Date: Fri, 21 Nov 2014 09:40:27 -0800 X-Google-Sender-Auth: chQnu6RMPUxTN6Gkm2aGhZ7pz68 Message-ID: Subject: Re: VIMAGE UDP memory leak fix From: Adrian Chadd To: "Robert N. M. Watson" Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Cc: Craig Rodrigues , FreeBSD Net , "Bjoern A. Zeeb" , Marko Zec X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 21 Nov 2014 17:40:32 -0000 On 21 November 2014 07:32, Robert N. M. Watson wrote: > > On 21 Nov 2014, at 15:20, Marko Zec wrote: > >>> Bjoern and I chatted for the last twenty or so minutes about the >>> code, and believe that as things stand, it is *not* safe to turn off >>> UMA_ZONE_NOFREE for TCP due to a teardown race in TCP that has been >>> known about and discussed for several years, but is some work to >>> resolve and that we've not yet found time to do so. The XXXRW's in >>> tcp_timer.c are related to this. We're pondering ways to fix it but >>> think this is not something that can be rushed. >> >> OK fair enough - thanks a lot for looking into this! >> >> Skimming through a bunch of hosts with moderately loaded hosts with >> reasonably high uptime I couldn't find one where net.inet.tcp.timer_race >> was not zero. A ny suggestions how to best reproduce the race(s) in >> tcp_timer.c? > > They would likely occur only on very highly loaded hosts, as they require= race conditions to arise between TCP timers and TCP close. I think I did m= anage to reproduce it at one stage, and left the counter in to see if we co= uld spot it in production, and I have had (multiple) reports of it in deplo= yed systems. I'm not sure it's worth trying to reproduce them, given that k= nowledge -- we should simply fix them. > Wasn't this just fixed by Julien @ Verisign? As for the vimage stability side of things - I'd really like to see some VIMAGE torture tests written. Stuff like "do a high rate TCP connection test whilst creating and destroying VIMAGEs." -adrian