Re: [tip:x86/mm] x86/mm/numa: Fix 32-bit kernel NUMA boot

[Lans Zhang <jia.zhang@windriver.com>]

On 12/20/2013 12:44 AM, Yinghai Lu wrote:
> On Thu, Dec 19, 2013 at 7:42 AM, tip-bot for Lans Zhang
> <tipbot@zytor.com>  wrote:
>> Commit-ID:  f3d815cb854b2f6262ade56a4d91a1ed3f1e50c4
>> Gitweb:     http://git.kernel.org/tip/f3d815cb854b2f6262ade56a4d91a1ed3f1e50c4
>> Author:     Lans Zhang<jia.zhang@windriver.com>
>> AuthorDate: Fri, 6 Dec 2013 12:18:30 +0800
>> Committer:  Ingo Molnar<mingo@kernel.org>
>> CommitDate: Thu, 19 Dec 2013 13:58:36 +0100
>>
>> x86/mm/numa: Fix 32-bit kernel NUMA boot
>>
>> When booting a 32-bit x86 kernel on a NUMA machine, node data
>> cannot be allocated from local node if the account of memory for
>> node 0 covers the low memory space entirely:
>>
>>    [    0.000000] Initmem setup node 0 [mem 0x00000000-0x83fffffff]
>>    [    0.000000]   NODE_DATA [mem 0x367ed000-0x367edfff]
>>    [    0.000000] Initmem setup node 1 [mem 0x840000000-0xfffffffff]
>>    [    0.000000] Cannot find 4096 bytes in node 1
>>    [    0.000000] 64664MB HIGHMEM available.
>>    [    0.000000] 871MB LOWMEM available.
>>
>> To fix this issue, node data is allowed to be allocated from
>> other nodes if the memory of local node is still not mapped. The
>> expected result looks like this:
>>
>>    [    0.000000] Initmem setup node 0 [mem 0x00000000-0x83fffffff]
>>    [    0.000000]   NODE_DATA [mem 0x367ed000-0x367edfff]
>>    [    0.000000] Initmem setup node 1 [mem 0x840000000-0xfffffffff]
>>    [    0.000000]   NODE_DATA [mem 0x367ec000-0x367ecfff]
>>    [    0.000000]     NODE_DATA(1) on node 0
>>    [    0.000000] 64664MB HIGHMEM available.
>>    [    0.000000] 871MB LOWMEM available.
>>
>> Signed-off-by: Lans Zhang<jia.zhang@windriver.com>
>> Cc:<andi@firstfloor.org>
>> Cc: Yinghai Lu<yinghai@kernel.org>
>> Link: http://lkml.kernel.org/r/1386303510-18574-1-git-send-email-jia.zhang@windriver.com
>> Signed-off-by: Ingo Molnar<mingo@kernel.org>
>> ---
>>   arch/x86/mm/numa.c | 10 +++++++---
>>   1 file changed, 7 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
>> index 24aec58..c85da7b 100644
>> --- a/arch/x86/mm/numa.c
>> +++ b/arch/x86/mm/numa.c
>> @@ -211,9 +211,13 @@ static void __init setup_node_data(int nid, u64 start, u64 end)
>>           */
>>          nd_pa = memblock_alloc_nid(nd_size, SMP_CACHE_BYTES, nid);
>>          if (!nd_pa) {
>> -               pr_err("Cannot find %zu bytes in node %d\n",
>> -                      nd_size, nid);
>> -               return;
>> +               nd_pa = __memblock_alloc_base(nd_size, SMP_CACHE_BYTES,
>> +                                             MEMBLOCK_ALLOC_ACCESSIBLE);
>> +               if (!nd_pa) {
>> +                       pr_err("Cannot find %zu bytes in node %d\n",
>> +                              nd_size, nid);
>> +                       return;
>> +               }
>>          }
>>          nd = __va(nd_pa);
>>
>
> Can you just use memblock_alloc_try_nid instead memblock_alloc_nid?

But memblock_alloc_base() inside memblock_alloc_try_nid() may cause kernel panic
if __memblock_alloc_base() inside it fails. In current stage, it is allowed if
node data fails to be allocated.

Thanks,
lz

>
> Thanks
>
> Yinghai
>