Re: [PATCH] mm: ksize() should silently accept a NULL pointer

[Matthew Wilcox]

On Wed, Jun 17, 2020 at 04:23:04PM +0000, Christopher Lameter wrote:
> On Tue, 16 Jun 2020, William Kucharski wrote:
> 
> > Other mm routines such as kfree() and kzfree() silently do the right
> > thing if passed a NULL pointer, so ksize() should do the same.
> 
> Ok so the size of an no object pointer is zero? Ignoring the freeing
> of a nonexisting object makes sense. But determining it size?

ksize() is misnamed.  It's not the size of the object, it's the number
of bytes allocated for that object.

A NULL pointer represents a freed object, or one that was never
allocated in the first place.  Clearly that's 0 bytes.  What other
answer would make sense?