Re: Kernel crash during video transcoding

From: Alexandre Levy <a13xlevy_at_gmail.com>
Date: Mon, 10 Aug 2020 09:41:08 +0100
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 août 2020 à 08:44, Hans Petter Selasky <hps_at_selasky.org> a
écrit :

> 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 = 0; apic id = 00
> > fault virtual address   = 0xdf
> > fault code              = supervisor read data, page not present
> > instruction pointer     = 0x20:0xffffffff80bdd2b4
> > stack pointer           = 0x0:0xfffffe00d2be56d0
> > frame pointer           = 0x0:0xfffffe00d2be56d0
> > code segment            = base 0x0, limit 0xfffff, type 0x1b
> >                          = DPL 0, pres 1, long 1, def32 0, gran 1
> > processor eflags        = interrupt enabled, resume, IOPL = 0
> > current process         = 4611 (Plex Transcoder)
> > trap number             = 12
> > panic: page fault
> > cpuid = 0
> > time = 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 = 0xffffffff80bdd2b4, rsp = 0xfffffe00d2be56d0, rbp =
> > 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 = 0x80296659a, rsp = 0x7fffffffbd38, rbp = 0x80fc00000
> ---
> > 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 USB
> > drive) :
> >
> > $ cat /etc/rc.conf | grep dump
> > dumpdev="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 compiled
> > 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.
> > _______________________________________________
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> >
>
>
Received on Mon Aug 10 2020 - 06:41:22 UTC

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