Re: [PATCH] mm/buddy: more comments for skip_free_areas_node()

[Gavin Shan <shangw@linux.vnet.ibm.com>]

On Mon, Jul 09, 2012 at 02:21:07PM -0700, David Rientjes wrote:
>On Fri, 6 Jul 2012, Gavin Shan wrote:
>
>> >> The initial idea comes from Cong Wang. We're running out of memory
>> >> while calling function skip_free_areas_node(). So it would be unsafe
>> >> to allocate more memory from either stack or heap. The patche adds
>> >> more comments to address that.
>> >
>> >I think these comments should add to show_free_areas(),
>> >not skip_free_areas_node().
>> >
>> 
>> aha, exactly. Thanks a lot, Cong.
>> 
>
>There are two issues you're trying to describe here that I told you about:
>
> - allocating memory on the stack when called in a potentially very deep 
>   call chain, and
>
> - dynamically allocating memory in oom conditions.
>
>There are thousands of functions that could be called potentially very 
>deep in a call chain, there's nothing special about this one besides the 
>fact that you tried to optimize it by allocating a nodemask on the stack 
>in a previous patch.
>
>show_mem(), which calls show_free_areas(), is also not called only in oom 
>conditions so the comment wouldn't apply at all.
>
>In other words, there's nothing special about this particular function 
>with regard to these traits.
>

Thanks for your review, David. So please drop it :-)

Thanks,
Gavin

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