From owner-freebsd-mips@FreeBSD.ORG Sat Sep 6 22:37:11 2014 Return-Path: Delivered-To: freebsd-mips@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 5E3533C6; Sat, 6 Sep 2014 22:37:11 +0000 (UTC) Received: from mail-qg0-x232.google.com (mail-qg0-x232.google.com [IPv6:2607:f8b0:400d:c04::232]) (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 F244E1E13; Sat, 6 Sep 2014 22:37:10 +0000 (UTC) Received: by mail-qg0-f50.google.com with SMTP id q108so13769065qgd.9 for ; Sat, 06 Sep 2014 15:37:10 -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=A1zz2bfCYg4BfvhcG5H2mgEHi4FLBHA3NoZTkEyqLzU=; b=A4PnpFJkQsh/xz8pcO07diaSpQ9VXVkweVe2HLIyhqt4787JVy6aFD8VJQO1KyJs6+ O4atDjjgeXSOVQJBTzxSm3nGBRFJNyNCM6TXbIFNnVxW8QY35IH5/YzGw5/sqsEfZOO2 fOPwKoHf5r7UCwhdkskDwY5FRHoIptnOTJ1tkDIJc5FdWKmyJCpPysQhxScOQws49KpL UMuMCyUmeN8WfCpel+Frg8TROOgWgVYkcvttayAPXeTjuxB9c8LFjdif3to4jFngsapa tr2BP3dIFDuoomU3XYLax/3CCMug3IH+qaMAO02r0UKDKJf3O20FeccwFeygaSSObX/O 3hdA== MIME-Version: 1.0 X-Received: by 10.224.36.4 with SMTP id r4mr29837286qad.69.1410043030210; Sat, 06 Sep 2014 15:37:10 -0700 (PDT) Sender: adrian.chadd@gmail.com Received: by 10.224.39.139 with HTTP; Sat, 6 Sep 2014 15:37:10 -0700 (PDT) In-Reply-To: <540B8AA0.40005@rice.edu> References: <540B8AA0.40005@rice.edu> Date: Sat, 6 Sep 2014 15:37:10 -0700 X-Google-Sender-Auth: p1F5wASzvdnb0hLvdd2l-XIbtCE Message-ID: Subject: Re: bug 193400: sfbuf changes on mips32 may have exposed some vm/pmap issues on mips32? From: Adrian Chadd To: Alan Cox Content-Type: text/plain; charset=UTF-8 Cc: Alan Cox , Gleb Smirnoff , "freebsd-mips@freebsd.org" X-BeenThere: freebsd-mips@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Porting FreeBSD to MIPS List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 06 Sep 2014 22:37:11 -0000 On 6 September 2014 15:28, Alan Cox wrote: > On 09/06/2014 17:24, Adrian Chadd wrote: >> Hi! >> >> This bug: >> >> https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=193400 >> >> is what I reported to alc a couple weeks ago as breaking on my 128mb >> RAM mipsbe board. >> >> It turns out that the difference between the MIPS32 sfbuf code and the >> new stuff gleb added was the refcounting side of things. With the MIPS >> code, there was no refcounting at all - each sfbuf allocation would >> allocate a new sfbuf. Now, I don't know how correct that is (my >> reading of the code is "not correct!") but it wasn't panicing things. >> >> So I think maybe gleb's patch to sfbuf exposed a MIPS32 pmap/VM bug? >> >> Alan - how would we go about figuring out what could be the issue here? > > I just sent you an email a few minutes ago describing how to restore the > old behavior. > Yup. I've also implemented the local sf_buf map and unmap routines; it seems to fix things. -a