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SubjectRe: [PATCH 3/3] x86: fix node_possible_map logic -v2
Yinghai Lu wrote:
> Jack Steiner wrote:
>> On Fri, May 08, 2009 at 11:50:51PM -0700, Yinghai Lu wrote:
>>> recently there are some changes to about meaning of node_possible_map
>>>
>>> and it is some strange:
>>> the node without memory would be set in node_possible_map
>>> but some node with less NODE_MIN_SIZE will be kicked out of node_possible_map.
>>>
>>> try to fix it by adding strict_setup_node_bootmem.
>>> also remove unparse_node.
>> I still see the same panic. Entry 0 of the node_data array is NULL &
>> it is dereferenced building the zonelists.
>>
>> I'm sure that you are way ahead of me in diagnosing this problem but
>> this is a regression from previous behavior. Fpor example, in 2.6.27, node_data
>> is created for both nodes but node 0 contains no memory:
>>
>> (2.7.27)
>> <6>SRAT: PXM 0 -> APIC 0 -> Node 0
>> <6>SRAT: PXM 1 -> APIC 128 -> Node 1
>> <6>SRAT: Node 1 PXM 1 0-fff6c000
>> <7>NUMA: Using 63 for the hash shift.
>> <6>Bootmem setup node 0 0000000000000000-0000000000000000
>> <3>Cannot find 212992 bytes in node 0
>> <6>Bootmem setup node 1 0000000000000000-0000000010000000
>> <6> NODE_DATA [000000000139be80 - 00000000013cfe7f]
>> <6> bootmap [00000000013d0000 - 00000000013d1fff] pages 2
>> <6>(7 early reservations) ==> bootmem [0000000000 - 0010000000]
>> <6> #0 [0000000000 - 0000001000] BIOS data page ==> [0000000000 - 0000001000]
>> <6> #1 [0000006000 - 0000008000] TRAMPOLINE ==> [0000006000 - 0000008000]
>> <6> #2 [0000200000 - 000139be38] TEXT DATA BSS ==> [0000200000 - 000139be38]
>> <6> #3 [000009f000 - 00000e0900] BIOS reserved ==> [000009f000 - 00000e0900]
>> <6> #4 [00000e0a68 - 0000100000] BIOS reserved ==> [00000e0a68 - 0000100000]
>> <6> #5 [00000e0900 - 00000e0a68] EFI memmap ==> [00000e0900 - 00000e0a68]
>> <6> #6 [0000001000 - 0000001030] ACPI SLIT ==> [0000001000 - 0000001030]
>> <6>Bootmem setup node 0 0000000000000000-0000000000000000
>> <6> NODE_DATA [00000000013d2000 - 0000000001405fff]
>> <6> bootmap [0000000000000000 - ffffffffffffffff] pages 0
>> <6>(7 early reservations) ==> bootmem [0000000000 - 0000000000]
>> <6> #0 [0000000000 - 0000001000] BIOS data page
>> <6> #1 [0000006000 - 0000008000] TRAMPOLINE
>> <6> #2 [0000200000 - 000139be38] TEXT DATA BSS
>> <6> #3 [000009f000 - 00000e0900] BIOS reserved
>> <6> #4 [00000e0a68 - 0000100000] BIOS reserved
>> <6> #5 [00000e0900 - 00000e0a68] EFI memmap
>> <6> #6 [0000001000 - 0000001030] ACPI SLIT
>> <6> NODE_DATA(0) on node 1
>> <6> bootmap(0) on node 1
>> <7> [ffffe20000000000-ffffe200003fffff] PMD -> [ffff880001600000-ffff8800019fffff] on node 1
>> <4>Zone PFN ranges:
>> <4> DMA 0x00000000 -> 0x00001000
>> <4> DMA32 0x00001000 -> 0x00100000
>> <4> Normal 0x00100000 -> 0x00100000
>> <4>Movable zone start PFN for each node
>> <4>early_node_map[2] active PFN ranges
>> <4> 1: 0x00000000 -> 0x00000006
>> <4> 1: 0x00000200 -> 0x00010000
>> <4>Could not find start_pfn for node 0
>> <7>On node 0 totalpages: 0
>> <7>On node 1 totalpages: 65030
>> <7> DMA zone: 3427 pages, LIFO batch:0
>> <7> DMA32 zone: 60480 pages, LIFO batch:15
>>
>> I have not seen any problems running on 2.6.27 using nodes that have no memory.
>>
>>
>> Do we have a clear and unambiguous definition of what a node really is?
>> In this case, is a board (socket) with cpus, a unique PXM but no memory
>> considered a node. Even though it has no memory, it is a node (depending on the
>> definition of "node") for purposes such as scheduling. The memoryless node also
>> has local IO buses that want to direct interrupts to node-local cpus.
>>
>
> how about 2.6.28, 29, and current linus tree?
>
> we should not have NODE_DATA to node that doesn't have memory.
>

also later if memory is hot add to that node, it will get NODE_DATA on the node later.

YH


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