linux-kernel - Re: [Bug #11313] Plugging HDMI causes "unable to handle kernel paging request"

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Date:	Thu, 21 Aug 2008 11:13:21 -0700
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Rafał Miłecki <zajec5@...il.com>
CC:	"Rafael J. Wysocki" <rjw@...k.pl>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Kernel Testers List <kernel-testers@...r.kernel.org>,
	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	Yinghai Lu <yhlu.kernel@...il.com>,
	Jack Steiner <steiner@....com>,
	Alan Jenkins <alan-jenkins@...fmail.co.uk>,
	Hugh Dickens <hugh@...itas.com>
Subject: Re: [Bug #11313] Plugging HDMI causes "unable to handle kernel paging
 request"

Rafał Miłecki wrote:
> I added full dmesg 5 minutes after adding grepped:
> http://bugzilla.kernel.org/attachment.cgi?id=17331
>   

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 0x13a600000
- 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 ==> [0000008000 - 000000b000]
  #6 [000000b000 - 000000c000]          PGTABLE ==> [000000b000 - 000000c000]
                                                     ^^^^^^^^^^^^^^^^^^^^^^^

IOW, it's mapping using b000-11000, but it has only reserved b000 - c000

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
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