From owner-freebsd-current@FreeBSD.ORG Mon Aug 13 12:31:27 2007 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id D4FD116A418 for ; Mon, 13 Aug 2007 12:31:27 +0000 (UTC) (envelope-from max@love2party.net) Received: from moutng.kundenserver.de (moutng.kundenserver.de [212.227.126.187]) by mx1.freebsd.org (Postfix) with ESMTP id 664C813C461 for ; Mon, 13 Aug 2007 12:31:27 +0000 (UTC) (envelope-from max@love2party.net) Received: from [88.66.55.99] (helo=amd64.laiers.local) by mrelayeu.kundenserver.de (node=mrelayeu7) with ESMTP (Nemesis), id 0ML2xA-1IKZ4i2gS8-0002Rr; Mon, 13 Aug 2007 14:31:23 +0200 From: Max Laier Organization: FreeBSD To: Pawel Jakub Dawidek Date: Mon, 13 Aug 2007 14:31:06 +0200 User-Agent: KMail/1.9.7 References: <6eb82e0708111122g7e36b725h19ede889e4bbc9d6@mail.gmail.com> <200708112129.29751.max@love2party.net> <20070811205437.GA24731@garage.freebsd.pl> In-Reply-To: <20070811205437.GA24731@garage.freebsd.pl> X-Face: ,,8R(x[kmU]tKN@>gtH1yQE4aslGdu+2]; R]*pL,U>^H?)gW@49@wdJ`H<=?utf-8?q?=25=7D*=5FBD=0A=09U=5For=3D=5CmOZf764=26nYj=3DJYbR1PW0ud?=>|!~,,CPC.1-D$FG@0h3#'5"k{V]a~.<=?utf-8?q?mZ=7D44=23Se=7Em=0A=09Fe=7E=5C=5DX5B=5D=5Fxj?=(ykz9QKMw_l0C2AQ]}Ym8)fU MIME-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart1983264.hrjkTlodga"; protocol="application/pgp-signature"; micalg=pgp-sha1 Content-Transfer-Encoding: 7bit Message-Id: <200708131431.13088.max@love2party.net> X-Provags-ID: V01U2FsdGVkX19hM5AdOsPV8pL5n1XbagCiXjHDKj9dUSKIKFP YNHgll18/sedRPEzz1lbLi/QGs7vypIs7Qa7gks7g4yO+OM4X9 b60EO/bqGLK78IjmSKQVqWh8QygWY9YPbvkWWFMjK4= Cc: freebsd-current@freebsd.org, Rong-en Fan , Kris Kennaway Subject: Re: panic: sleeping thread owns a non-sleepable lock X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 13 Aug 2007 12:31:27 -0000 --nextPart1983264.hrjkTlodga Content-Type: text/plain; charset="iso-8859-6" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline On Saturday 11 August 2007, Pawel Jakub Dawidek wrote: > On Sat, Aug 11, 2007 at 09:29:23PM +0200, Max Laier wrote: > > On Saturday 11 August 2007, Kris Kennaway wrote: > > > On Sun, Aug 12, 2007 at 02:22:35AM +0800, Rong-en Fan wrote: > > > > I'm running 7.0-CURRENT as of yesterday, and it's very easy > > > > to make it panic: > > > > > > > > Sleeping thread (tid 100065, pid 1066) owns a non-sleepable lock > > > > sched_switch(c50a1600,0,1,1c7a7e4,4217e5,...) at > > > > sched_switch+0x190 mi_switch(1,0) at mi_switch+0x13f > > > > sleepq_switch(c50a1600,0,c078a4e2,21b,c07e3820,...) at > > > > sleepq_switch+0x87 sleepq_wait(c07e3820,0,c0770b7e,3,0,...) at > > > > sleepq_wait+0x36 _sx_xlock_hard(c07e3820,c50a1600,0,0,0,...) at > > > > _sx_xlock_hard+0x21d > > > > fr_checknatout(f9c7a8d0,f9c7a8cc,64,c57ad900,c4de7400,...) at > > > > fr_checknatout+0x29d > > > > fr_check(c8cc4644,14,c4de7400,1,f9c7a9b4,...) at fr_check+0x9b1 > > > > fr_check_wrapper(0,f9c7a9b4,c4de7400,2,c54dab28,...) at > > > > fr_check_wrapper+0x3f > > > > pfil_run_hooks(c08057c0,f9c7aa4c,c4de7400,2,c54dab28,...) at > > > > pfil_run_hooks+0x74 ip_output(c8cc4600,0,f9c7aa10,0,0,...) at > > > > ip_output+0x913 > > > > tcp_output(cae322d0,cb277200,0,0,0,...) at tcp_output+0x1106 > > > > tcp_usr_send(c51e7318,0,cb277200,0,0,...) at tcp_usr_send+0x240 > > > > kern_sendfile(c50a1600,f9c7acfc,0,0,0,...) at > > > > kern_sendfile+0x1037 > > > > sendfile(c50a1600,f9c7acfc,20,16,f9c7ad2c,...) at sendfile+0xa8 > > > > syscall(f9c7ad38) at syscall+0x315 > > > > Xint0x80_syscall() at Xint0x80_syscall+0x20 > > > > --- syscall (393, FreeBSD ELF32, sendfile), eip =3D 0x28290bff, esp > > > > =3D 0xbfbfc6ac, ebp =3D 0xbfbfe718 --- > > > > > > What is the lock it holds, and where is it acquired? > > > > My bet is on the pfil rwlock - accquired in pfil_run_hooks and > > tcbinfo / inp mtxs from tcp_output. Nothing in the transmission path > > must use sx locks. I keep on telling that. > > It looks like a whole lot of complex code can be run with pfil rwlock > held. More complex code - harder to avoid sleeping. Is it not possible > to call ->pfil_func() without holding pfil rwlock? For example by > acquiring the lock, taking a hook, increasing its reference count so it > won't go away, dropping the lock and calling ->pfil_func() ? Won't help a bit. There are other locks on the way that would need=20 similar changes. I believe that things that hook into pfil(9) must be=20 aware that they are running in the hot transmission path. Actions that=20 can not be performed with a mutex held must be deferred to another=20 context. Note that traditional pfil(9) consumers used to run at splnet,=20 where sleeping is a bad idea as well. =2D-=20 /"\ Best regards, | mlaier@freebsd.org \ / Max Laier | ICQ #67774661 X http://pf4freebsd.love2party.net/ | mlaier@EFnet / \ ASCII Ribbon Campaign | Against HTML Mail and News --nextPart1983264.hrjkTlodga Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.4 (FreeBSD) iD8DBQBGwE8RXyyEoT62BG0RAjEEAJ9cYzhsSPGPtxo6lWYWzi6BgK3R4QCfeMzy xF3FUNd1f8yPxqqXWAQGdKU= =W9Ca -----END PGP SIGNATURE----- --nextPart1983264.hrjkTlodga--