Re: [RFC][PATCH v3] slub: Keep page and object in sync inslab_alloc_node()

[Christoph Lameter]

On Fri, 18 Jan 2013, Eric Dumazet wrote:

> On Fri, 2013-01-18 at 18:40 +0000, Christoph Lameter wrote:
>
> > The fetching of the tid is the only critical thing here. If the tid is
> > retrieved from the right cpu then the cmpxchg will fail if any changes
> > occured to freelist or the page variable.
> >
> > The tid can be retrieved without disabling preemption through
> > this_cpu_read().
>
> Strictly speaking, this_cpu_read() _does_ disable preemption.

Yes on x86 the relocation and the fetch is just a single instruction and
therefore no preemption can occur.

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