Date: Fri, 26 Jan 2018 07:07:10 -0800 From: David Wolfskill <david@catwhisker.org> To: Warner Losh <imp@bsdimp.com> Cc: FreeBSD Current <current@freebsd.org> Subject: Re: Panic on shutdown @r328436: "Unholding 6 with cnt = -559038242" Message-ID: <20180126150710.GV1287@albert.catwhisker.org> In-Reply-To: <CANCZdfqWs_1Ss_oJ0ik8r17uDRyUN8nk%2Bt9DS=zZ=j92Xz=qZA@mail.gmail.com> References: <20180126122947.GA1287@albert.catwhisker.org> <CANCZdfqWs_1Ss_oJ0ik8r17uDRyUN8nk%2Bt9DS=zZ=j92Xz=qZA@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
--LJa15rN3LQ9Y2Ulo Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Jan 26, 2018 at 07:47:48AM -0700, Warner Losh wrote: > On Fri, Jan 26, 2018 at 5:29 AM, David Wolfskill <david@catwhisker.org> > wrote: >=20 > > This is on my "build machine" (laptop is still building updated ports > > for today, so I don't know yet whether or not it encounters this.) > > >=20 > Running a kernel with INVARIANTS, right? Yes -- GENERIC. > > I had performed a source-based update from r328393 to r328436, > > rebooted, performed "make delete-old-libs", and all seemed well. > > >=20 > This has my change 328415 in it. :-) > > I then issued "sudo shutdown -p now", and serial console shows: > > panic: Unholding 6 with cnt =3D -559038242 > > cpuid =3D 3 > > time =3D 1516968697 > > KDB: stack backtrace: > > db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame > > 0xfffffe00004288c0 > > vpanic() at vpanic+0x18d/frame 0xfffffe0000428920 > > panic() at panic+0x43/frame 0xfffffe0000428980 > > dadiskgonecb() at dadiskgonecb+0x42/frame 0xfffffe00004289a0 > > g_disk_providergone() at g_disk_providergone+0x25/frame 0xfffffe0000428= 9d0 > > g_destroy_provider() at g_destroy_provider+0xae/frame 0xfffffe00004289f0 > > g_wither_washer() at g_wither_washer+0x87/frame 0xfffffe0000428a30 > > g_run_events() at g_run_events+0x3ca/frame 0xfffffe0000428a70 > > fork_exit() at fork_exit+0x84/frame 0xfffffe0000428ab0 > > fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe0000428ab0 > > --- trap 0, rip =3D 0, rsp =3D 0, rbp =3D 0 --- > > KDB: enter: panic > > [ thread pid 13 tid 100044 ] > > Stopped at kdb_enter+0x3b: movq $0,kdb_why > > db> > > >=20 > That's no good. We're releasing a reference to the da peripheral because > geom has finished with the disk and is giving us a final callback so we c= an > drop the reference we took when we created the geom. Trouble is, cnt shou= ld > be like 1 always for this code, but it's not. It looks like it may be byt= es > to a pointer :( >=20 >=20 > > As noted, this is a build machine, and it was to be powered off for > > the rest of the day anyway, so I don't need to get it up & running > > immediately: I can poke at the ddb prompt, given some clues. > > >=20 > I don't suppose you can attach kgdb to this machine? I'd be interested to > see what the contents of the softc are...a Pointer to how to do that? I do have ddb right now.... > .... > Thanks for the report. This is quite troubling. Well, let's get it fixed, then! :-) > Warner > .... I should still have access to the serial console after I get in to the office (heading out shortly). Peace, david --=20 David H. Wolfskill david@catwhisker.org "unfortunately, no trust!=E2=80=9D -- well, of course! You reap what you s= ow. See http://www.catwhisker.org/~david/publickey.gpg for my public key. --LJa15rN3LQ9Y2Ulo Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQGTBAEBCgB9FiEEzLfO+ReoAfQwZNd7FTnMQKBJ7hcFAlprRB1fFIAAAAAALgAo aXNzdWVyLWZwckBub3RhdGlvbnMub3BlbnBncC5maWZ0aGhvcnNlbWFuLm5ldEND QjdDRUY5MTdBODAxRjQzMDY0RDc3QjE1MzlDQzQwQTA0OUVFMTcACgkQFTnMQKBJ 7hfNdggAqYHLXjkXPcdnKW8jgNJz3GCXvzzq7Dn9RMcpvXZnyOYbI2Lz+suwNgDn sOvSzQfXkG2QvvLyGQxsueSAKW/OOo06/Xtd6lwkwikHuTR+swjymI5SQZcBHs+3 Th92uwfMKRB9SPbhbyF/kBw0P+EsBAMpq/jnsSF6p4aL5qfJT+G0d8t228O2l2fR KKsaWU7uz6T9b9Zcn0JWzgyzKyw87UHRX8bm6xalLT3OhrwVvnC4kBNegJrfBEbK nZlTXcsTR7Q2SlJ+UXjzGpr2nzmBbV9c2g8gRqc2Akfhm468PahjmNdjILVCEEG/ OvriPQ3pIZLDy4hDehz7zwttUCo4MA== =ualf -----END PGP SIGNATURE----- --LJa15rN3LQ9Y2Ulo--
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20180126150710.GV1287>