Re: [PATCH v2] NUMA x86: add constraints check for nid parameters

[David Rientjes]

On Thu, 8 Dec 2011, Andi Kleen wrote:

> > This patch adds constraints checks for numa_set_distance()
> > function. It emits warning when pxms are used uninitialized
> > when parsing the SRAT.
> 
> Can you expand on the motivation for this please?

It's adding a debugging check if something erroneously passes a negative 
node id when setting a distance, perhaps because of buggy code that failed 
to initialize the pxm-to-node mapping correctly which would result in 
storing to a negative index of the numa_distance array as indicated in the 
changelog.  It's for robustness and to warn explicitly rather than 
silently rejecting it unless you're monitoring debug output.
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