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Date:      Mon, 10 Aug 2020 09:41:08 +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:  <CAEWSB323KtVrixgRyKsekdgcGjFm4kUqG6qDE59Aev3Cc6sYBg@mail.gmail.com>
In-Reply-To: <13793020-1bde-b13f-65e3-909e27d876ad@selasky.org>
References:  <CAEWSB323c2zapSG30OS5T30Wd_bpT=7NbvrPtsyQDRRHQUf7qA@mail.gmail.com> <13793020-1bde-b13f-65e3-909e27d876ad@selasky.org>

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I'm recompiling the kernel using GENERIC at the moment but I'm not sure how
to enable debugging in i915 kms, there is no compile option for that, am I
missing something ?

Le lun. 10 ao=C3=BBt 2020 =C3=A0 08:44, Hans Petter Selasky <hps@selasky.or=
g> a
=C3=A9crit :

> Hi,
>
> On 2020-08-10 00:19, Alexandre Levy wrote:
> > Hi,
> >
> > I installed the port drm-devel-kmod for Plex to be able to transcode
> videos
> > using the integrated GPU of my Intel Celeron G5900.
> >
> > I'm running r364031 and the kernel is compiled with GENERIC-NODEBUG
> profile.
> >
> > Transcoding has been working fine for quite a while now but one video
> > transcoding is causing a kernel panic that is reproducible all the time
> > with that particular video. It seems like it's caused by the i915kms
> module
> > (call of i915_gms_fault() in the stack) :
>
> If you compile the kernel using GENERIC and then enable debugging in the
> i915 kms and reproduce, we might get a more clear picture!
>
> It is a so called NULL pointer you've experienced.
>
> --HPS
>
> >
> > Fatal trap 12: page fault while in kernel mode
> > cpuid =3D 0; apic id =3D 00
> > fault virtual address   =3D 0xdf
> > fault code              =3D supervisor read data, page not present
> > instruction pointer     =3D 0x20:0xffffffff80bdd2b4
> > stack pointer           =3D 0x0:0xfffffe00d2be56d0
> > frame pointer           =3D 0x0:0xfffffe00d2be56d0
> > code segment            =3D base 0x0, limit 0xfffff, type 0x1b
> >                          =3D DPL 0, pres 1, long 1, def32 0, gran 1
> > processor eflags        =3D interrupt enabled, resume, IOPL =3D 0
> > current process         =3D 4611 (Plex Transcoder)
> > trap number             =3D 12
> > panic: page fault
> > cpuid =3D 0
> > time =3D 1596976796
> > KDB: stack backtrace:
> > db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame
> > 0xfffffe00d2be5390
> > vpanic() at vpanic+0x182/frame 0xfffffe00d2be53e0
> > panic() at panic+0x43/frame 0xfffffe00d2be5440
> > trap_fatal() at trap_fatal+0x387/frame 0xfffffe00d2be54a0
> > trap_pfault() at trap_pfault+0x4f/frame 0xfffffe00d2be54f0
> > trap() at trap+0x271/frame 0xfffffe00d2be5600
> > calltrap() at calltrap+0x8/frame 0xfffffe00d2be5600
> > --- trap 0xc, rip =3D 0xffffffff80bdd2b4, rsp =3D 0xfffffe00d2be56d0, r=
bp =3D
> > 0xfffffe00d2be56d0 ---
> > _rw_wowned() at _rw_wowned+0x4/frame 0xfffffe00d2be56d0
> > vm_page_busy_acquire() at vm_page_busy_acquire+0x141/frame
> > 0xfffffe00d2be5710
> > remap_io_mapping() at remap_io_mapping+0x120/frame 0xfffffe00d2be5760
> > i915_gem_fault() at i915_gem_fault+0x25f/frame 0xfffffe00d2be57d0
> > linux_cdev_pager_populate() at linux_cdev_pager_populate+0x11b/frame
> > 0xfffffe00d2be5840
> > vm_fault() at vm_fault+0x3d1/frame 0xfffffe00d2be5950
> > vm_fault_trap() at vm_fault_trap+0x60/frame 0xfffffe00d2be5990
> > trap_pfault() at trap_pfault+0x19c/frame 0xfffffe00d2be59e0
> > trap() at trap+0x3f1/frame 0xfffffe00d2be5af0
> > calltrap() at calltrap+0x8/frame 0xfffffe00d2be5af0
> > --- trap 0xc, rip =3D 0x80296659a, rsp =3D 0x7fffffffbd38, rbp =3D 0x80=
fc00000
> ---
> > KDB: enter: panic
> >
> > I don't see any crash dump in /var/crash despite having the right
> > configuration and I should have enough space on my swap device (128GB U=
SB
> > drive) :
> >
> > $ cat /etc/rc.conf | grep dump
> > dumpdev=3D"AUTO"
> >
> > $ swapinfo
> > Device          1K-blocks     Used    Avail Capacity
> > /dev/gpt/crash0 121307096        0 121307096     0%
> >
> > $ cat /etc/fstab
> > /dev/gpt/crash0 none    swap    sw              0       0
> >
> > $ dumpon -l
> > gpt/crash0
> >
> > Not sure why no dump was generated, is it because the kernel was compil=
ed
> > with the GENERIC-NODEBUG profile ? However I see various KDB options in
> the
> > GENERIC profile that are inherited by GENERIC-NODEBUG.
> >
> > Happy to recompile the kernel with GENERIC profile if it's required.
> >
> > Thank you.
> > _______________________________________________
> > freebsd-current@freebsd.org mailing list
> > https://lists.freebsd.org/mailman/listinfo/freebsd-current
> > To unsubscribe, send any mail to "
> freebsd-current-unsubscribe@freebsd.org"
> >
>
>



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