From nobody Mon Aug 30 07:28:55 2021 X-Original-To: freebsd-net@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id E43641788386 for ; Mon, 30 Aug 2021 07:28:58 +0000 (UTC) (envelope-from avg@FreeBSD.org) Received: from smtp.freebsd.org (smtp.freebsd.org [96.47.72.83]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "smtp.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4GyhlG6DF1z4b24; Mon, 30 Aug 2021 07:28:58 +0000 (UTC) (envelope-from avg@FreeBSD.org) Received: from [192.168.0.88] (unknown [195.64.148.76]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client did not present a certificate) (Authenticated sender: avg/mail) by smtp.freebsd.org (Postfix) with ESMTPSA id 654412D161; Mon, 30 Aug 2021 07:28:58 +0000 (UTC) (envelope-from avg@FreeBSD.org) From: Andriy Gapon To: "Alexander V. Chernikov" Cc: freebsd-net References: <2fbc5205-3fcc-d233-dae1-cf6ddc8d691d@FreeBSD.org> <95F4F779-91A0-482B-B26B-6C95A60FC281@ipfw.ru> <70d1091d-07ec-1c76-29bc-1f2e2264b55a@FreeBSD.org> <869483A6-FA65-40A2-9CCC-05216588EAC8@ipfw.ru> Subject: Re: network crash in nhop_free Message-ID: <6a1874fc-a5ac-31a3-13ee-390177091ce6@FreeBSD.org> Date: Mon, 30 Aug 2021 10:28:55 +0300 User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:78.0) Gecko/20100101 Firefox/78.0 Thunderbird/78.13.0 List-Id: Networking and TCP/IP with FreeBSD List-Archive: https://lists.freebsd.org/archives/freebsd-net List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-net@freebsd.org MIME-Version: 1.0 In-Reply-To: <869483A6-FA65-40A2-9CCC-05216588EAC8@ipfw.ru> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-ThisMailContainsUnwantedMimeParts: N On 01/08/2021 16:36, Alexander V. Chernikov wrote: > > >> On 10 Jul 2021, at 10:07, Andriy Gapon wrote: >> >> On 09/07/2021 00:02, Alexander V. Chernikov wrote: >>> Hi Andriy, >>> Could you by any chance provide a bit more info on the system networking configuration and the steps leading to panic? >>> No chance for a coredump? >>> destroy_nhgrp() suggests that there was a multipath route (default?) that was deleted. >>> nhops are created with UMA_ALIGN_PTR, so I suspect there is a garbage inside nhgrp pointer.. >> >> I've just reproduced the problem and got a crash dump. >> The new panic is a little bit different, but I think that it confirms your analysis. >> Also, you are right about the multipath route, although its creation was not intentional. > > Should be fixed by https://cgit.freebsd.org/src/commit/?id=054948bd81bb9e4e32449cf351b62e501b8831ff . I have to report that, unfortunately, as of main bb958dcf3d8af3a033dacbf8133681c9b0c73b2f I can still reproduce the same panic using the same steps. To be clear, as I reported two similar but still distinct panics, it's the first panic, "Misaligned access from kernel space!". I should also add that the commit message does not really match my scenario. In my case routes do not change quite fast. I have generous pauses between starting and stopping ppp. I have a feeling that there must something more deterministic that leads to the crash. -- Andriy Gapon