Date: Fri, 26 Jan 2018 07:47:48 -0700 From: Warner Losh <imp@bsdimp.com> To: FreeBSD Current <current@freebsd.org> Subject: Re: Panic on shutdown @r328436: "Unholding 6 with cnt = -559038242" Message-ID: <CANCZdfqWs_1Ss_oJ0ik8r17uDRyUN8nk%2Bt9DS=zZ=j92Xz=qZA@mail.gmail.com> In-Reply-To: <20180126122947.GA1287@albert.catwhisker.org> References: <20180126122947.GA1287@albert.catwhisker.org>
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On Fri, Jan 26, 2018 at 5:29 AM, David Wolfskill <david@catwhisker.org> wrote: > 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.) > Running a kernel with INVARIANTS, right? > I had performed a source-based update from r328393 to r328436, > rebooted, performed "make delete-old-libs", and all seemed well. > This has my change 328415 in it. > I then issued "sudo shutdown -p now", and serial console shows: > panic: Unholding 6 with cnt = -559038242 > cpuid = 3 > time = 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 0xfffffe00004289d0 > 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 = 0, rsp = 0, rbp = 0 --- > KDB: enter: panic > [ thread pid 13 tid 100044 ] > Stopped at kdb_enter+0x3b: movq $0,kdb_why > db> > 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 can drop the reference we took when we created the geom. Trouble is, cnt should be like 1 always for this code, but it's not. It looks like it may be bytes to a pointer :( > 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. > 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 > Same system had completed a source-based update for stable/11 from > r328392 to r328429 earlier today without incident (using a different > slice of the boot drive). > Thanks for the report. This is quite troubling. Warner
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