From owner-freebsd-hackers Wed Mar 27 13:49: 5 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from albatross.prod.itd.earthlink.net (albatross.mail.pas.earthlink.net [207.217.120.120]) by hub.freebsd.org (Postfix) with ESMTP id 3A3A937B405; Wed, 27 Mar 2002 13:49:00 -0800 (PST) Received: from pool0142.cvx21-bradley.dialup.earthlink.net ([209.179.192.142] helo=mindspring.com) by albatross.prod.itd.earthlink.net with esmtp (Exim 3.33 #1) id 16qLHr-0000pw-00; Wed, 27 Mar 2002 13:48:55 -0800 Message-ID: <3CA23E31.CDAA9A78@mindspring.com> Date: Wed, 27 Mar 2002 13:48:33 -0800 From: Terry Lambert X-Mailer: Mozilla 4.7 [en]C-CCK-MCD {Sony} (Win98; U) X-Accept-Language: en MIME-Version: 1.0 To: Alfred Perlstein Cc: jeff@freebsd.org, hackers@freebsd.org Subject: Re: uma and double free detection? References: <20020327203236.GN93885@elvis.mu.org> <3CA239BB.A9A8F72A@mindspring.com> <20020327213247.GO93885@elvis.mu.org> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Alfred Perlstein wrote: > * Terry Lambert [020327 13:30] wrote: > > Alfred Perlstein wrote: > > > > > > Can uma diagnose double free's? It doesn't seem to be able to > > > under a GENERIC config. :( > > > > THat's an INVARIANTS thing, even without UMA... > > /usr/src/sys/i386/conf % grep INVA BRIGHT > options INVARIANTS #Enable calls of extra sanity checking > options INVARIANT_SUPPORT #Extra sanity checks of internal structu > > All I got was a panic because uma seemed to get confused rather than > catch the double free. I got a similar untraceable panic because the ucred reference counter was overlayed with an invariants structure. Probably invariants is stomping something that is used as a marker into seeming validity. It's very tempting to require that invariants add their own crap to to the front of a structure, and then hide it, so that this is not possible. It was a real pain in the butt to track doewn the cred free problem. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message