Date: Sun, 16 Aug 2020 21:23:05 +0100 From: Alexandre Levy <a13xlevy@gmail.com> To: Hans Petter Selasky <hps@selasky.org> Cc: freebsd-current@freebsd.org Subject: Re: Kernel crash during video transcoding Message-ID: <CAEWSB32P47nCfa7%2BKhBNg89hPx_rrsWrRobVV6v4zxX0UGzNJw@mail.gmail.com> In-Reply-To: <5fe820c0-69af-8c41-69d6-a3c33ed55e2e@selasky.org> References: <CAEWSB323c2zapSG30OS5T30Wd_bpT=7NbvrPtsyQDRRHQUf7qA@mail.gmail.com> <13793020-1bde-b13f-65e3-909e27d876ad@selasky.org> <CAEWSB323KtVrixgRyKsekdgcGjFm4kUqG6qDE59Aev3Cc6sYBg@mail.gmail.com> <4e9d9a89-4883-1f1c-c796-e5925fd171cc@selasky.org> <CAEWSB30YNwQ7Bpv00P-B=TTHCqT_aFm30552n51Pic1uN5hnZQ@mail.gmail.com> <CAEWSB33_ka2aQb81UmODu72Be_9Vvqi4Qb-jfXHEZ1HgCqwADQ@mail.gmail.com> <51a2fe4f-5a3e-8d24-19e2-3cdaa8378015@selasky.org> <CAEWSB32oKbaE4M=V3H8F9rJv%2BL1ivKejhGAXmHMxOKkyYQLCxg@mail.gmail.com> <CAEWSB33-harOEk3v4rWBMQQJwfOtJmap-qBqAjc33__nLYKLrQ@mail.gmail.com> <5fe820c0-69af-8c41-69d6-a3c33ed55e2e@selasky.org>
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"m" is not NULL :
(kgdb) frame 16
#16 0xffffffff80ec23ed in vm_page_busy_acquire (m=3D0xfffffe00040ff9e8,
allocflags=3D16) at /usr/src/sys/vm/vm_page.c:884
(kgdb) p *m
$2 =3D {plinks =3D {q =3D {tqe_next =3D 0x578491b51dd60510, tqe_prev =3D
0xd78c11bd9dde8518}, s =3D {ss =3D {sle_next =3D 0x578491b51dd60510}}, memg=
uard =3D
{p =3D 6306325585301210384,
v =3D 15531808720989095192}, uma =3D {slab =3D 0x578491b51dd60510, zo=
ne =3D
0xd78c11bd9dde8518}}, listq =3D {tqe_next =3D 0xd78c11bd9dde8518, tqe_prev =
=3D
0x265bc92017d7aa38},
object =3D 0x2659c92217d5aa3a, pindex =3D 2758957463725517354, phys_addr =
=3D
2758957463725517354, md =3D {pv_list =3D {tqh_first =3D 0x2e49c1321fc5a22a,
tqh_last =3D 0x3e4bd1300fc7b228},
pv_gen =3D 265794104, pat_mode =3D 1046204704}, ref_count =3D 257405624=
,
busy_lock =3D 1054593440, a =3D {{flags =3D 4757, queue =3D 48 '0', act_cou=
nt =3D 134
'\206'}, _bits =3D 2251297429},
order =3D 98 'b', pool =3D 204 '\314', flags =3D 75 'K', oflags =3D 105 '=
i',
psind =3D -107 '\225', segind =3D 18 '\022', valid =3D 48 '0', dirty =3D 13=
4 '\206'}
I had to recompile drm-devel-kmod with make WITH_DEBUG=3Dyes DEBUG_FLAGS=3D=
"-g
-O0" because "m" was optimized out. I then started a kgdb session with the
same crash dump than before, loaded the module symbols with add-kld
/boot/modules/i915kms.ko and I now have a different backtrace from frames
#17 to #28.
Also the panic doesn't occur when I plug a screen to the HDMI port (which
now works for some reason...) and I can see the frame #17 is now the
following :
#17 0xffffffff82b4e980 in intel_plane_can_remap
(plane_state=3D0xfffff80315148300)
at
/usr/ports/graphics/drm-devel-kmod/work/drm-kmod-drm_v5.3_4/drivers/gpu/drm=
/i915/display/intel_display.c:2583
and used to be :
#17 0xffffffff82b4e980 in remap_io_mapping (vma=3D0xfffff80315148300,
addr=3D<optimized out>, pfn=3D<optimized out>, size=3D<optimized out>,
iomap=3D<optimized out>)
I don't understand why the backtrace changed although the crash dump is the
same as before. Any suggestions ?
Le dim. 16 ao=C3=BBt 2020 =C3=A0 18:19, Hans Petter Selasky <hps@selasky.or=
g> a
=C3=A9crit :
> On 2020-08-16 17:28, Alexandre Levy wrote:
> > Now at intel_freebsd.c:193 (frame #17) the driver calls
> > vm_page_busy_acquire(m, VM_ALLOC_WAITFAIL). 'm' is the page grabbed fro=
m
> > vm_obj of the calling frame.
>
> Can you check if "m" is NULL at this point?
>
> --HPS
>
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