linux-kernel - Re: Suspected regression in "x86: extend e820 ealy

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Message-ID: <86802c440805211540m4ff68aeh827a1f823305742b@mail.gmail.com>
Date:	Wed, 21 May 2008 15:40:56 -0700
From:	"Yinghai Lu" <yhlu.kernel@...il.com>
To:	"Jeremy Fitzhardinge" <jeremy@...p.org>
Cc:	"Ingo Molnar" <mingo@...e.hu>,
	"kernel list" <linux-kernel@...r.kernel.org>,
	"Thomas Gleixner" <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: Suspected regression in "x86: extend e820 ealy_res support 32bit"

On Wed, May 21, 2008 at 3:01 PM, Jeremy Fitzhardinge <jeremy@...p.org> wrote:
> Yinghai Lu wrote:
>>
>> On Wed, May 21, 2008 at 11:19 AM, Jeremy Fitzhardinge <jeremy@...p.org>
>> wrote:
>>
>>>
>>> I'm seeing a crash in current x86.git tip/auto-latest when booting under
>>> Xen.  The crash is rather early, but it's in __alloc_bootmem_core() in
>>> the
>>> final memset clear.  Apparently the allocator is returning a bad page.
>>>
>>> This points to changes in the setup of the bootmem allocator, and the
>>> changes "x86: extend e820 ealy_res support 32bit" make to
>>> arch/x86/kernel/setup_32.c:setup_bootmem_allocator() looks like the most
>>> likely suspect.  Unfortunately its a rather large patch which is not easy
>>> to
>>> revert, so I haven't actually confirmed this yet.
>>>
>>
>>
>> thanks. please check the attached patch
>>
>
> Thanks for the quick response.  I definitely confirmed that "x86: extend
> e820 ealy_res support 32bit" is the source of the regression, and reverting
> the change makes the system bootable under Xen. (My previous reversion
> failed because I didn't actually have the x86.git changes applied :-/)
>
> This patch generates the warning:
>
>     CC      arch/x86/kernel/setup_32.o
>   /home/jeremy/hg/xen/paravirt/linux/arch/x86/kernel/setup_32.c: In
>   function 'setup_arch':
>   /home/jeremy/hg/xen/paravirt/linux/arch/x86/kernel/setup_32.c:580:
>   warning: 'bootmap_size' is used uninitialized in this function
>
> but I think it's just that the panic() message still uses it before its
> assigned.
>
> Hm, and it also fails to fix the problem.  I'm still seeing the virtual
> machine crash in the same way.

noticed that bootmap_size is shifted already...

please use attached patch to see if bootmap is right...

YH

View attachment "bootmap_32_fix.patch" of type "text/x-patch" (903 bytes)