From owner-freebsd-arm@FreeBSD.ORG Mon Mar 23 00:41:57 2015 Return-Path: Delivered-To: arm@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 8F9DF8E4; Mon, 23 Mar 2015 00:41:57 +0000 (UTC) Received: from mail-lb0-x22e.google.com (mail-lb0-x22e.google.com [IPv6:2a00:1450:4010:c04::22e]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 0FC0AED2; Mon, 23 Mar 2015 00:41:57 +0000 (UTC) Received: by lbbsy1 with SMTP id sy1so108192023lbb.1; Sun, 22 Mar 2015 17:41:55 -0700 (PDT) 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; bh=5KgTg+mP+EfUzZxN281ZmZZfVrP+GEPqjA8EopJHUhA=; b=ra1GWnvCvjoyM5IkS2bKDaO/fi7U6ARvMThXaqeXisiw8yOl0aUX35DgFTDhhbI09X bd01qxtg/2OUv+nlySrxV/OcyFKWgN2IgtTmIAhhHRtkWpQn80Jt5cAZrnFwEbwuqvey AuEd10XOKGxLkdGY5Bn0L56DCcnAncVhxyxX7dKqEdPbSL3UZHEVsYOwve2xQTe4eCwa wjS6xKybx4SAmCfuggn2sPxOK70msMiAvHzM1Ljy272XrZ60nWj3DGX5AfT9ENKdPP6H Z+4sHDAqCauhk+WQKvG4bVW3Gl23Ls/f8pUm27y/qRXT+7f2e4OUfKoMPm6ffQptCHGf HAdQ== MIME-Version: 1.0 X-Received: by 10.112.122.108 with SMTP id lr12mr66225275lbb.25.1427071315176; Sun, 22 Mar 2015 17:41:55 -0700 (PDT) Sender: zbodek@gmail.com Received: by 10.112.163.194 with HTTP; Sun, 22 Mar 2015 17:41:55 -0700 (PDT) In-Reply-To: <1EFF2C41-456C-476E-9BA8-712E62DF0D4E@gromit.dlib.vt.edu> References: <1EFF2C41-456C-476E-9BA8-712E62DF0D4E@gromit.dlib.vt.edu> Date: Mon, 23 Mar 2015 01:41:55 +0100 X-Google-Sender-Auth: 76F8SpERE2wFT1-uf_QVyLTM0OQ Message-ID: Subject: Re: panic: pmap_demote_section: No l2_bucket for wired mapping From: Zbigniew Bodek To: Paul Mather Content-Type: text/plain; charset=UTF-8 Cc: "freebsd-arm@freebsd.org" X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: "Porting FreeBSD to ARM processors." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 23 Mar 2015 00:41:57 -0000 2015-03-22 20:45 GMT+01:00 Paul Mather : > On Mar 22, 2015, at 7:54 AM, Michael Tuexen wrote: > >> Dear all, >> >> running head on a Raspberry Pi became unstable. When running >> r280329 for a while (the machine is exposed to the Internet, so >> ssh logins are continuously tried), the machine panics: >> >> panic: pmap_demote_section: No l2_bucket for wired mapping >> KDB: enter: panic > > > I get this panic when booting to multi-user on my newly-updated BBB (FreeBSD 11.0-CURRENT #0 r280350). As pointed out later in this thread, setting vm.pmap.sp_enabled=0 prevents the panic (so far) and allows booting. > > Cheers, > > Paul. > I was able to reproduce this on my R-Pi too. The bug may be related to shared libraries mapping since excluding pmap_enter_section() (the one in the pmap_enter_object() that is responsible for doing the work for shared libraries mappings) results in normal operation even with page promotion/demotion enabled. I will try to find some time to look into that to ensure that this is not just covering the problem. If it doesn't then we may consider disabling pmap_enter_section() (by adding "return FALSE;") to have WA (without disabling superpages) until we find the real solution. pmap_enter_section() was being used very rarely before shared libraries superpage mappings were enabled so it is reasonable to think that the bug is somewhere around. Please let me know in case you find something. Best regards zbb