From owner-freebsd-current Sat Apr 15 11:23:16 2000 Delivered-To: freebsd-current@freebsd.org Received: from apollo.backplane.com (apollo.backplane.com [216.240.41.2]) by hub.freebsd.org (Postfix) with ESMTP id 15CB237B5D4; Sat, 15 Apr 2000 11:23:13 -0700 (PDT) (envelope-from dillon@apollo.backplane.com) Received: (from dillon@localhost) by apollo.backplane.com (8.9.3/8.9.1) id LAA79731; Sat, 15 Apr 2000 11:23:11 -0700 (PDT) (envelope-from dillon) Date: Sat, 15 Apr 2000 11:23:11 -0700 (PDT) From: Matthew Dillon Message-Id: <200004151823.LAA79731@apollo.backplane.com> To: Brian Fundakowski Feldman Cc: Alfred Perlstein , Michael Reifenberger , , alc@FreeBSD.ORG Subject: Re: panic: vm_object_shadow: source object has OBJ_ONEMAPPING set. References: Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG :Well, first the question must be answered, in an absolute yes or no: :is it wrong in the first place to have OBJ_ONEMAPPING set with a ref_count :of more than 1? I'd accept an authoritative answer about this from :alc, dillon, dyson, or luoqi, who are all very familiar with the new :VM. :-- : Brian Fundakowski Feldman \ FreeBSD: The Power to Serve! / : green@FreeBSD.org `------------------------------' It is totally legal for OBJ_ONEMAPPING to be set even if the ref_count is greater then 1. The ref_count has no bearing on the shareability of the object any more. The tests were there before due to all sorts of crud that had been hacked in in the 2.2.x and 3.x era to get around serious bugs in the OBJ_ONEMAPPING flag and elsewhere in the VM system. 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. -Matt Matthew Dillon To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message