Re: [PATCH 16/35] x86: make 64 bit use early_res instead of bootmembefore slab

From: Yinghai Lu
Date: Wed Feb 24 2010 - 21:14:26 EST


On 02/24/2010 06:07 PM, Tejun Heo wrote:
> Hello, Yinghai.
>
> On 02/25/2010 08:32 AM, Yinghai Lu wrote:
>>>> Kernel panic - not syncing: free_early on not reserved area: 2f80000-2f9ffff!
>>>> Pid: 0, comm: swapper Not tainted 2.6.33-rc8-tip-00918-gb34d361 #159
>>>> Call Trace:
>>>> [<ffffffff815d12e2>] panic+0x84/0x147
>>>> [<ffffffff81cceecb>] free_early+0x64/0x6d
>>>> [<ffffffff81cd2231>] free_bootmem+0xc/0xe
>>>> [<ffffffff81cc1cd6>] pcpu_fc_free+0x1d/0x1f
>>>> [<ffffffff81cd6056>] pcpu_embed_first_chunk+0x13a/0x27f
>>>> [<ffffffff81cc1cd8>] ? pcpu_fc_alloc+0x0/0xac
>>>> [<ffffffff81cc1cb9>] ? pcpu_fc_free+0x0/0x1f
>>>> [<ffffffff81cc1af7>] setup_per_cpu_areas+0x82/0x239
>>>> [<ffffffff81cb5b3c>] start_kernel+0x1b8/0x43b
>>>> [<ffffffff81cb52bc>] x86_64_start_reservations+0xa7/0xab
>>>> [<ffffffff81cb53b8>] x86_64_start_kernel+0xf8/0x107
>>>>
>>>
>>> we can not handle partial free, and current only user for that is pcpu_setup...
>>
>> any plan to pcpu_setup to use slab allocation instead of bootmem?
>> that code is only one user that do partial bootmem free.
>
> The problem is that the pcpu_embed_first_chunk() allocator depends on
> having a large contiguous slab of memory to overlay the percpu
> variables and then giving back the unused parts (due to layout and
> cpu_possible_mask not being contiguous). There's no way to do partial
> alloc/free anymore?

ok, will add free_early_partial to handle it.

i got impression, when we are moving slab ealier.
you said that will check to make percpu setup to use slab allocator instead.

YH
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