On 03/05/2010 02:26 AM, Jiri Slaby wrote:
> On 03/05/2010 10:04 AM, Yinghai Lu wrote:
>> according to context
>> http://patchwork.kernel.org/patch/73893/
>>
>> Jiri, 
>> please check current linus tree still have problem about mem_map is using that much low mem?
> 
> Hi!
> 
> Sorry, I don't have direct access to the machine. I might try to ask the
> owners to do so.
> 
>> on my 1024g system first node has 128G ram, [2g, 4g) are mmio range.
> 
> So where gets your mem_map allocated (I suppose you're running flat model)?
> 
> Note that the failure we were seeing was with different amount of memory
> on different machines. Obviously because of different e820 reservations
> and driver requirements at boot time. So the required memory to trigger
> the error oscillated around 128G, sometimes being 130G.
> 
> It triggered when mem_map fit exactly into 0-2G (and 2-4G was reserved)
> and no more space was there. If RAM was more than 130G, mem_map was
> above 4G boundary implicitly, so that there was enough space in the
> first 4G of memory for others with specific bootmem limitations.
> 
>> with NO_BOOTMEM
>> [    0.000000]  a - 11
>> [    0.000000]  19 40 - 80 95
>> [    0.000000]  702 740 - 1000 1000
>> [    0.000000]  331f 3340 - 3400 3400
>> [    0.000000]  35dd - 3600
>> [    0.000000]  37dd - 3800
>> [    0.000000]  39dd - 3a00
>> [    0.000000]  3bdd - 3c00
>> [    0.000000]  3ddd - 3e00
>> [    0.000000]  3fdd - 4000
>> [    0.000000]  41dd - 4200
>> [    0.000000]  43dd - 4400
>> [    0.000000]  45dd - 4600
>> [    0.000000]  47dd - 4800
>> [    0.000000]  49dd - 4a00
>> [    0.000000]  4bdd - 4c00
>> [    0.000000]  4ddd - 4e00
>> [    0.000000]  4fdd - 5000
>> [    0.000000]  51dd - 5200
>> [    0.000000]  93dd 9400 - 7d500 7d53b
>> [    0.000000]  7f730 - 7f750
>> [    0.000000]  100012 100040 - 100200 100200
>> [    0.000000]  170200 170200 - 2080000 2080000
>> [    0.000000]  2080065 2080080 - 2080200 2080200
>>
>> so PFN: 9400 - 7d500 are free.
> 
> Could you explain more the dmesg output?

it will list free pfn range that will be use for slab...

attached is debug patch for print out without CONFIG_NO_BOOTMEM set.

YH