From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeremy Fitzhardinge <jeremy-TSDbQ3PG+2Y@public.gmane.org>
Subject: Re: [Bug #11313] Plugging HDMI causes "unable to handle kernel paging
 request"
Date: Thu, 21 Aug 2008 11:13:21 -0700
Message-ID: <48ADB041.9040806@goop.org>
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Cc: "Rafael J. Wysocki" <rjw-KKrjLPT3xs0@public.gmane.org>, Linux Kernel Mailing List <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Kernel Testers List <kernel-testers-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Ingo Molnar <mingo-X9Un+BFzKDI@public.gmane.org>, "H. Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>, Yinghai Lu <yhlu.kernel-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Jack Steiner <steiner-sJ/iWh9BUns@public.gmane.org>, Alan Jenkins <alan-jenkins-cCz0Lq7MMjm9FHfhHBbuYA@public.gmane.org>, Hugh Dickens <hugh-DTz5qymZ9yRBDgjK7y7TUQ@public.gmane.org>

Rafa=C5=82 Mi=C5=82ecki wrote:
> I added full dmesg 5 minutes after adding grepped:
> http://bugzilla.kernel.org/attachment.cgi?id=3D17331
>  =20

OK, I think I see the problem (pasted from bugzilla comment):

>>>>
Some notes as I pick through all the evidence so far:

- the crash is specifically because there are reserved bits set in the =
pmd
- the pmd is b02a00043a6001a3 in both cases
- the vaddr is ffff88013a600000 in the first crash, and
               ffff81013a6d1c00 in the second
  corresponding to the same large-page pmd mapping of phys page 0x13a60=
0000
- this maps to e820 entry
 BIOS-e820: 0000000100000000 - 0000000140000000 (usable)
- the corresponding boot-time mapping is

init_memory_mapping
 0100000000 - 0140000000 page 2M
kernel direct mapping tables up to 140000000 @ b000-11000
                                               ^^^^^^^^^^
addr 100000000 reusing pgd 201880 0000000000202063
last_map_addr: 140000000 end: 140000000

!!! and the memory allocated for this pagetable is:
  #5 [0000008000 - 000000b000]          PGTABLE =3D=3D> [0000008000 - 0=
00000b000]
  #6 [000000b000 - 000000c000]          PGTABLE =3D=3D> [000000b000 - 0=
00000c000]
                                                     ^^^^^^^^^^^^^^^^^^=
^^^^^

IOW, it's mapping using b000-11000, but it has only reserved b000 - c00=
0

Also, this is right in the middle of the ISA area, which seems risky.
<<<<

Bug #11237 shows the same symptom, so I'm pretty confident they're dups=
 now.

    J