Re: [PATCH 1/2] mm, slob: Prevent false positive trace upon allocation failure

Pekka Enberg
2012-08-15T12:43:07Z

On Wed, Aug 15, 2012 at 3:34 PM, Ezequiel Garcia <elezegarcia@gmail.com> wrote:
> As you can see this patch prevents to trace a kmem event if the allocation
> fails.
>
> I'm still unsure about tracing or not this ones, and I'm considering tracing
> failures, perhaps with return=0 and allocated size=0.
>
> In this case, it would be nice to have SLxB all do the same.
> Right now, this is not the case.
>
> You can see how slob::kmem_cache_alloc_node traces independently
> of the allocation succeeding.
> I have no problem trying a fix for this, but I don't now how to trace
> this cases.
>
> Although it is a corner case, I think it's important to define a clear
> and consistent behaviour to make tracing reliable.

Agreed on consistency. I think it's valuable to be able to trace
allocation failures and let userspace filter them out if they don't
need them.