Re: [RESEND PATCH v5 3/4] mm/vmalloc: revert "mm/vmalloc.c: check VM_UNINITIALIZED flag in s_show instead of show_numa_info"

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Hi KOSAKI,
On Mon, Sep 16, 2013 at 05:23:32PM -0400, KOSAKI Motohiro wrote:
>On 9/14/2013 7:45 PM, Wanpeng Li wrote:
>> Changelog:
>>  *v2 -> v3: revert commit d157a558 directly
>> 
>> The VM_UNINITIALIZED/VM_UNLIST flag introduced by commit f5252e00(mm: avoid
>> null pointer access in vm_struct via /proc/vmallocinfo) is used to avoid
>> accessing the pages field with unallocated page when show_numa_info() is
>> called. This patch move the check just before show_numa_info in order that
>> some messages still can be dumped via /proc/vmallocinfo. This patch revert 
>> commit d157a558 (mm/vmalloc.c: check VM_UNINITIALIZED flag in s_show instead 
>> of show_numa_info);
>
>Both d157a558 and your patch don't explain why your one is better. Yes, some
>messages _can_ be dumped. But why should we do so?

More messages can be dumped and original commit f5252e00(mm: avoid null pointer 
access in vm_struct via /proc/vmallocinfo) do that. 

>
>And No. __get_vm_area_node() doesn't use __GFP_ZERO for allocating vm_area_struct.
>dumped partial dump is not only partial, but also may be garbage.

vm_struct is allocated by kzalloc_node.

>
>I wonder why we need to call setup_vmalloc_vm() _after_ insert_vmap_area.

I think it's another topic. 

Fill vm_struct and set VM_VM_AREA flag. If I misunderstand your
question?

Regards,
Wanpeng Li 

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