From owner-freebsd-stable Tue Sep 7 17:54:44 1999 Delivered-To: freebsd-stable@freebsd.org Received: from dingo.cdrom.com (dingo.cdrom.com [204.216.28.145]) by hub.freebsd.org (Postfix) with ESMTP id 53BDA15403 for ; Tue, 7 Sep 1999 17:54:38 -0700 (PDT) (envelope-from mike@dingo.cdrom.com) Received: from dingo.cdrom.com (localhost.cdrom.com [127.0.0.1]) by dingo.cdrom.com (8.9.3/8.8.8) with ESMTP id RAA01782; Tue, 7 Sep 1999 17:46:13 -0700 (PDT) (envelope-from mike@dingo.cdrom.com) Message-Id: <199909080046.RAA01782@dingo.cdrom.com> X-Mailer: exmh version 2.0.2 2/24/98 To: Jeremy McMillan Cc: stable@freebsd.org Date: Tue, 07 Sep 1999 17:46:13 -0700 From: Mike Smith Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Fcc: sent Subject: Re: newly introduced repeatable SMP hang in STABLE/3.3-RC In-reply-to: Your message of "Tue, 07 Sep 1999 19:30:25 CDT." Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii -------- > Could this be that one kernel thread is wedged in a state where it has a > lock on a resource, but it can still do low level functions like handle > ICMP? Maybe the other thread hung, and thus cannot release the lock on > whatever resource the working (ICMP reachable kernel thread) needs to > resume process managment services? What kernel resource do threads take > turns locking? A 'wedged' host that is pingable is locked in the kernel for some reason, but without at least some interrupts masked. ICMP echo replies are generated in interrupt context. If the machine is pingable but you can't get to DDB, chances are that you're in some code running at spltty, which may be code related to serial I/O, console output, or printer I/O. In particular, turning off an attached printer can cause this. (I don't think this is the plaintiff's problem though.) -- \\ The mind's the standard \\ Mike Smith \\ of the man. \\ msmith@freebsd.org \\ -- Joseph Merrick \\ msmith@cdrom.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message