Re: [PATCH] slab: deal with NULL pointers passed to kmem_cache_free

[Jarek Poplawski <jarkao2@o2.pl>]

On Wed, Mar 21, 2007 at 03:36:34PM +0200, Pekka J Enberg wrote:
> On Wed, 21 Mar 2007, Jarek Poplawski wrote:
> > With  __kmem_cache_free you would set #1 I hope, but if
> > nobody would use this - debugging time wouldn't change.
> 
> I think you got it backwards. I suggested making the _current_ 
> kmem_cache_free() deal with NULL (so everyone will get it) and add a new 
> optimized __kmem_cache_free() for those call-sites that really need it.

If you could assure optimized version will be used only with
buggy-free code, so you don't waste time for debugging it,
then I really got it backwards, sorry!

> 
> On Wed, 21 Mar 2007, Jarek Poplawski wrote:
> > This could be acceptable, if there were no problems
> > with fixing the errors. But there are problems - bugs
> > like this aren't fixed on time - maybe because people
> > waste too much time per bug?
> 
> You're barking up the wrong tree here, Jarek. I strongly feel that we 
> should be more defensive in the slab for the exact reasons you outlined. 
> There's bunch of bug reports people seem to dismiss as slab errors where 
> in fact it's caused by a buggy caller.

But I can see only one tree here. And I seem to agree with all the rest.
So, I probably really got it backwards...

Must be going to find the right tree,
Jarek P.