From owner-freebsd-current@FreeBSD.ORG Sun Mar 2 20:14:45 2008 Return-Path: Delivered-To: current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 05454106566B for ; Sun, 2 Mar 2008 20:14:45 +0000 (UTC) (envelope-from jmg@hydrogen.funkthat.com) Received: from hydrogen.funkthat.com (gate.funkthat.com [69.17.45.168]) by mx1.freebsd.org (Postfix) with ESMTP id A82CB8FC23 for ; Sun, 2 Mar 2008 20:14:44 +0000 (UTC) (envelope-from jmg@hydrogen.funkthat.com) Received: from hydrogen.funkthat.com (jq8i8dn8amgh2zjr@localhost.funkthat.com [127.0.0.1]) by hydrogen.funkthat.com (8.13.6/8.13.3) with ESMTP id m22JrYC3065869; Sun, 2 Mar 2008 11:53:34 -0800 (PST) (envelope-from jmg@hydrogen.funkthat.com) Received: (from jmg@localhost) by hydrogen.funkthat.com (8.13.6/8.13.3/Submit) id m22JrYRS065868; Sun, 2 Mar 2008 11:53:34 -0800 (PST) (envelope-from jmg) Date: Sun, 2 Mar 2008 11:53:34 -0800 From: John-Mark Gurney To: Kostik Belousov Message-ID: <20080302195334.GI96595@funkthat.com> Mail-Followup-To: Kostik Belousov , current@freebsd.org References: <20080302152523.GO57756@deviant.kiev.zoral.com.ua> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080302152523.GO57756@deviant.kiev.zoral.com.ua> User-Agent: Mutt/1.4.2.1i X-Operating-System: FreeBSD 5.4-RELEASE-p6 i386 X-Files: The truth is out there X-URL: http://resnet.uoregon.edu/~gurney_j/ X-Resume: http://resnet.uoregon.edu/~gurney_j/resume.html X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-3.0 (hydrogen.funkthat.com [127.0.0.1]); Sun, 02 Mar 2008 11:53:34 -0800 (PST) X-Mailman-Approved-At: Sun, 02 Mar 2008 20:28:50 +0000 Cc: current@freebsd.org Subject: Re: knlsit_cleardel() panic X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: John-Mark Gurney List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 02 Mar 2008 20:14:45 -0000 Kostik Belousov wrote this message on Sun, Mar 02, 2008 at 17:25 +0200: > The panic below was already reported, but now I got it on my desktop > and was able to investigate further. > > #5 0xc06daf36 in trap (frame=0xe8093b1c) > at /usr/bsd/src/sys/i386/i386/trap.c:490 > #6 0xc06c0b4b in calltrap () at /usr/bsd/src/sys/i386/i386/exception.s:139 > #7 0xc0493968 in knlist_cleardel (knl=0xcabec128, td=0x0, islocked=1, > killkn=0) at atomic.h:149 > #8 0xc04f520c in pipeclose (cpipe=0xcabec0b8) > at /usr/bsd/src/sys/kern/sys_pipe.c:1508 > #9 0xc04f5320 in pipe_close (fp=0xc5ce8630, td=0xcac01aa0) > at /usr/bsd/src/sys/kern/sys_pipe.c:1425 > #10 0xc0489442 in fdrop (fp=0xc5ce8630, td=0xcac01aa0) at file.h:297 > #11 0xc048accf in closef (fp=0xc5ce8630, td=0xcac01aa0) > at /usr/bsd/src/sys/kern/kern_descrip.c:1958 > #12 0xc048b1ff in kern_close (td=0xcac01aa0, fd=10) > at /usr/bsd/src/sys/kern/kern_descrip.c:1054 > #13 0xc048b2da in close (td=0xcac01aa0, uap=0xe8093cfc) > at /usr/bsd/src/sys/kern/kern_descrip.c:1006 > ---Type to continue, or q to quit--- > #14 0xc06da865 in syscall (frame=0xe8093d38) > at /usr/bsd/src/sys/i386/i386/trap.c:1035 > #15 0xc06c0bb0 in Xint0x80_syscall () > at /usr/bsd/src/sys/i386/i386/exception.s:196 > > At the frame 8, we have > (kgdb) p/x *(knl->kl_list->slh_first) > $9 = {kn_link = {sle_next = 0x0}, kn_selnext = {sle_next = 0x0}, > kn_knlist = 0x0, kn_tqe = {tqe_next = 0xc58de484, tqe_prev = 0xc5e9ab20}, > kn_kq = 0x0, kn_kevent = {ident = 0x0, filter = 0x0, flags = 0x0, > fflags = 0x0, data = 0x0, udata = 0x0}, kn_status = 0x20, > kn_sfflags = 0x0, kn_sdata = 0x0, kn_ptr = {p_fp = 0x0, p_proc = 0x0, > p_aio = 0x0, p_lio = 0x0}, kn_fop = 0x0, kn_hook = 0x0} > > The knote is KN_MARKER, and the kn_kq is NULL. The result is that KQ_LOCK > in the knlist_cleardel()::SLIST_FOREACH_SAFE() loop dereferences NULL and > panics. > > Does the following change makes any sense? I thought this was a bug, but upon further examination, there is something wrong... a KN_MARKER knote should never be on the knlist.. It is only ever added to kq's even list, never to an object's list... If you could walk the knl->kl_list through kn_selnext, and ensure that the kn w/ kN_MARKER exists would be good... It should be the last one as kn_selnext is NULL... I can't think of a way that this can happen, as the only way to get on the knlist is by calling knlist_add, and it should only ever be called from f_attach, which is called in one place, and has to have kn_kq set properly... Are there any custom patches on the system? -- John-Mark Gurney Voice: +1 415 225 5579 "All that I will do, has been done, All that I have, has not."