Re: Memory allocator semantics

Christoph Lameter
2014-02-11T18:43:57Z

On Tue, 11 Feb 2014, Pekka Enberg wrote:

> So again, there's nothing in (A) that the memory allocator is
> concerned about. kmalloc() makes no guarantees whatsoever about the
> visibility of "r1" across CPUs. If you're saying that there's an
> implicit barrier between kmalloc() and kfree(), that's an unintended
> side-effect, not a design decision AFAICT.

I am not sure that this side effect necessarily happens. The SLUB fastpath
does not disable interrupts and only uses a cmpxchg without lock
semantics.