From owner-freebsd-current Sat Apr 15 16: 2:48 2000 Delivered-To: freebsd-current@freebsd.org Received: from cs.rice.edu (cs.rice.edu [128.42.1.30]) by hub.freebsd.org (Postfix) with ESMTP id 19E8D37B79A; Sat, 15 Apr 2000 16:02:45 -0700 (PDT) (envelope-from alc@cs.rice.edu) Received: (from alc@localhost) by cs.rice.edu (8.9.0/8.9.0) id SAA15973; Sat, 15 Apr 2000 18:02:43 -0500 (CDT) Date: Sat, 15 Apr 2000 18:02:43 -0500 From: Alan Cox To: Brian Fundakowski Feldman Cc: Matthew Dillon , Alfred Perlstein , Michael Reifenberger , current@freebsd.org, alc@freebsd.org Subject: Re: panic: vm_object_shadow: source object has OBJ_ONEMAPPING set. Message-ID: <20000415180243.D3462@cs.rice.edu> References: <200004151823.LAA79731@apollo.backplane.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.95.5us In-Reply-To: ; from Brian Fundakowski Feldman on Sat, Apr 15, 2000 at 06:12:22PM -0400 Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Sat, Apr 15, 2000 at 06:12:22PM -0400, Brian Fundakowski Feldman wrote: > On Sat, 15 Apr 2000, Matthew Dillon wrote: > > > Note that the ref_count == 1 test in the vm_object_shadow optimization > > should be left intact. This optimization requires a much stricter set > > of tests because we do not want to assume sharability of an object > > if someone else (the 'else' being 'someone unknown to us') has a reference > > on it, even if OBJ_ONEMAPPING is set. > > The KASSERT is broken in another way, BTW: it has undefined (read: > panic before the test even occurs) results if source is NULL, which > vm_object_shadow otherwise handles. I don't know why it's never been > tripped on, though... > Other parts of the VM insure that we never try to create a shadow object for a non-existant backing object. Alan To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message