Date: Mon, 30 Aug 2021 10:28:55 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: "Alexander V. Chernikov" <melifaro@ipfw.ru> Cc: freebsd-net <freebsd-net@FreeBSD.org> Subject: Re: network crash in nhop_free Message-ID: <6a1874fc-a5ac-31a3-13ee-390177091ce6@FreeBSD.org> In-Reply-To: <869483A6-FA65-40A2-9CCC-05216588EAC8@ipfw.ru> References: <2fbc5205-3fcc-d233-dae1-cf6ddc8d691d@FreeBSD.org> <d1e5e244-09e2-c30c-d08c-95d907c72f18@FreeBSD.org> <95F4F779-91A0-482B-B26B-6C95A60FC281@ipfw.ru> <70d1091d-07ec-1c76-29bc-1f2e2264b55a@FreeBSD.org> <869483A6-FA65-40A2-9CCC-05216588EAC8@ipfw.ru>
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On 01/08/2021 16:36, Alexander V. Chernikov wrote: > > >> On 10 Jul 2021, at 10:07, Andriy Gapon <avg@FreeBSD.org> 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
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