linux-kernel - Re: kdump broken on 2.6.37-rc4

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Date:	Thu, 16 Dec 2010 15:49:38 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	"H. Peter Anvin" <hpa@...or.com>
CC:	Vivek Goyal <vgoyal@...hat.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Stanislaw Gruszka <sgruszka@...hat.com>,
	Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Maxim Uvarov <muvarov@...il.com>, linux-kernel@...r.kernel.org,
	Neil Horman <nhorman@...hat.com>,
	Jeremy Fitzhardinge <jeremy@...p.org>
Subject: Re: kdump broken on 2.6.37-rc4

On 12/16/2010 03:30 PM, Yinghai Lu wrote:
> On 12/16/2010 11:58 AM, H. Peter Anvin wrote:
>> On 12/16/2010 09:28 AM, Yinghai Lu wrote:
>>>
>>> the brk is complaining if i change that to 
>>>
>>>  	if (end > ((-__PAGE_OFFSET-(128 <<20)-1) & 0x7fffffff))
>>>  		error("Destination address too large");
>>>
>>> brk is complaining when try to get more for dmi ...
>>> ...
>>> I'm in purgatory
>>> bootconsole [uart0] enabled
>>> Kernel Layout:
>>>   .text: [0x2e000000-0x2e3f08ca]
>>> .rodata: [0x2e3f2000-0x2e5a2fff]
>>>   .data: [0x2e5a3000-0x2e5f6467]
>>>   .init: [0x2e5f7000-0x2e670fff]
>>>    .bss: [0x2e675000-0x2e76ffff]
>>>    .brk: [0x2e770000-0x2e894fff]
>>>     memblock_x86_reserve_range: [0x00001000-0x00001fff]    EX TRAMPOLINE
>>>     memblock_x86_reserve_range: [0x2e000000-0x2e76ffff]    TEXT DATA BSS
>>>     memblock_x86_reserve_range: [0x35bdd000-0x35f49fff]          RAMDISK
>>>     memblock_x86_reserve_range: [0x0009c800-0x000fffff]  * BIOS reserved
>>> Initializing cgroup subsys cpuset
>>> Initializing cgroup subsys cpu
>>> Linux version 2.6.37-rc5-tip+ (root@...12-3214-189-181) (gcc version 4.4.4 20100726 (Red Hat 4.4.4-13) (GCC) ) #4 SMP Wed Dec 15 11:04:32 PST 2010
>>> KERNEL supported cpus:
>>>   Intel GenuineIntel
>>>   AMD AuthenticAMD
>>>   NSC Geode by NSC
>>>   Cyrix CyrixInstead
>>>   Centaur CentaurHauls
>>>   Transmeta GenuineTMx86
>>>   Transmeta TransmetaCPU
>>>   UMC UMC UMC UMC
>>> BIOS-provided physical RAM map:
>>>  BIOS-e820: [0x00000000000100-0x0000000009c7ff] (usable)
>>>  BIOS-e820: [0x0000000009c800-0x0000000009ffff] (reserved)
>>>  BIOS-e820: [0x000000000e0000-0x000000000fffff] (reserved)
>>>  BIOS-e820: [0x00000000100000-0x0000007ff9ffff] (usable)
>>>  BIOS-e820: [0x0000007ffae000-0x0000007ffaffff] (usable)
>>>  BIOS-e820: [0x0000007ffb0000-0x0000007ffbdfff] (ACPI data)
>>>  BIOS-e820: [0x0000007ffbe000-0x0000007ffeffff] (ACPI NVS)
>>>  BIOS-e820: [0x0000007fff0000-0x0000007fffffff] (reserved)
>>>  BIOS-e820: [0x000000e0000000-0x000000efffffff] (reserved)
>>>  BIOS-e820: [0x000000fec00000-0x000000fec00fff] (reserved)
>>>  BIOS-e820: [0x000000fee00000-0x000000feefffff] (reserved)
>>>  BIOS-e820: [0x000000ff700000-0x000000ffffffff] (reserved)
>>> last_pfn = 0x7ffb0 max_arch_pfn = 0x1000000
>>> NX (Execute Disable) protection: active
>>> user-defined physical RAM map:
>>>  user: [0x00000000000000-0x0000000009ffff] (usable)
>>>  user: [0x0000002e000000-0x00000035f59fff] (usable)
>>>  user: [0x0000007ffb0000-0x0000007ffeffff] (ACPI data)
>>> DMI present.
>>> BUG: Int 6: CR2   (null)
>>>      EDI 00000019  ESI ff940c18  EBP   (null)  ESP ee5a5e84
>>>      EBX ee5cfb68  EDX 00000006  ECX 00000019  EAX ee8e6019
>>>      err   (null)  EIP ee5fb4dd   CS 00000060  flg 00010002
>>> Stack: 00000019 ee62bf45 ff942000 00000563 00000001 ff940c00 000018c7 ee62bf83
>>>        ff940c00 ee62c063 80000000 ee3e6f2f ee50a3c0 ee5a5ed4 ff940c00 ff940c43
>>>        000018c7   (null) ee3173d4 000018c8 0000007f ff940c00 ff90b1bf ee5a5f18
>>> Pid: 0, comm: swapper Not tainted 2.6.37-rc5-tip+ #4
>>> Call Trace:
>>>  [<ee3dd1d5>] ? hlt_loop+0x0/0x3
>>>  [<ee5fb4dd>] ? extend_brk+0x31/0x44
>>
>> I'm assuming it bails due to:
>>
>> 	BUG_ON((char *)(_brk_end + size) > __brk_limit);
>>
>> ... could you find out what _brk_end and __brk_limit are?
> 
> void __init print_kernel_layout(void)
> {
>         printk("Kernel Layout:\n");
>         printk("  .text: [%#010lx-%#010lx]\n", __pa_symbol(&_text), __pa_symbol(&_etext) - 1);
>         printk(".rodata: [%#010lx-%#010lx]\n", __pa_symbol(&__start_rodata), __pa_symbol(&__end_rodata) - 1);
>         printk("  .data: [%#010lx-%#010lx]\n", __pa_symbol(&_sdata), __pa_symbol(&_edata) - 1);
>         printk("  .init: [%#010lx-%#010lx]\n", __pa_symbol(&__init_begin), __pa_symbol(&__init_end) - 1);
>         printk("   .bss: [%#010lx-%#010lx]\n", __pa_symbol(&__bss_start), __pa_symbol(&__bss_stop) - 1);
>         printk("   .brk: [%#010lx-%#010lx]\n", __pa_symbol(&__brk_base), __pa_symbol(&__brk_limit) - 1);
> }
> 
>>> Kernel Layout:
>>>   .text: [0x2e000000-0x2e3f08ca]
>>> .rodata: [0x2e3f2000-0x2e5a2fff]
>>>   .data: [0x2e5a3000-0x2e5f6467]
>>>   .init: [0x2e5f7000-0x2e670fff]
>>>    .bss: [0x2e675000-0x2e76ffff]
>>>    .brk: [0x2e770000-0x2e894fff]
> 
> DMI present.
> _brk_end: ee8e6000, __brk_limit: ee895000 
> 

looks like in arch/x86/kernel/head_32.S
will put page_table in _brk....

if the whole range is some high, it will use more buffer in _brk for ...

brk pre-calucation could be wrong and too small.

Yinghai
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