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

[David Rientjes <rientjes@google.com>]

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.

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