Re: kdump broken on 2.6.37-rc4

[Yinghai Lu <yinghai@kernel.org>]

On 12/16/2010 08:28 AM, H. Peter Anvin wrote:
> On 12/16/2010 06:39 AM, Vivek Goyal wrote:
>> On Wed, Dec 15, 2010 at 08:29:01PM -0800, Yinghai Lu wrote:
>>> please check
>>>
>>> [PATCH] x86, crashkernel, 32bit: only try to get range under 512M
>>>
>>> Steanishlaw report kdump is 32bit is broken.
>>>
>>> in misc.c for decompresser, it will do sanity checking to make sure heap
>>> heap under 512M.
>>
>> Thanks Yinghai. I am wondering why on 32bit heap has to be with-in 512MB.
>> I think you are referring to following check in
>> arch/x86/boot/compressed/misc.c.
>>
>> 	if (end > ((-__PAGE_OFFSET-(512 <<20)-1) & 0x7fffffff))
>> 		error("Destination address too large");
>>
>> It was introduced here.
>>
>> commit 968de4f02621db35b8ae5239c8cfc6664fb872d8
>> Author: Eric W. Biederman <ebiederm@xmission.com>
>> Date:   Thu Dec 7 02:14:04 2006 +0100
>>
>>     [PATCH] i386: Relocatable kernel support
>>
>> Eric,
>>
>> It has been long. By any chance would you remember where does above
>> constraint come from?
>>
> 
> It might, in fact, be bogus; specifically a proxy for the fact that we
> need the kernel memory including bss and brk below the lowmem boundary,
> which isn't well-defined.

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@mpk12-3214-189-181) (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
 [<ee62bf45>] ? dmi_string+0x2d/0x55
 [<ee62bf83>] ? dmi_save_ident+0x16/0x23
 [<ee62c063>] ? dmi_decode+0x5e/0x40c
 [<ee3e6f2f>] ? printk+0x17/0x20
 [<ee3173d4>] ? dmi_table+0x84/0x90
 [<ee62bd52>] ? dmi_present+0x112/0x1a6
 [<ee62c005>] ? dmi_decode+0x0/0x40c
 [<ee62be63>] ? dmi_scan_machine+0x7d/0xc9
 [<ee5facd6>] ? setup_arch+0x4b1/0xc87
 [<ee3e6f2f>] ? printk+0x17/0x20
 [<ee60f76d>] ? cgroup_init_subsys+0xcf/0xe5
 [<ee5f7828>] ? start_kernel+0xbb/0x38b
 [<ee5f70e2>] ? i386_start_kernel+0xe2/0xed