On Fri, 2013-01-18 at 10:04 -0500, Steven Rostedt wrote:
Just to be more complete:
> CPU0 CPU1
> ---- ----
c = __this_cpu_ptr(s->cpu_slab);
<migrates to CPU0>
> <cpu fetches c->page>
<another task>
> updates c->tid
> updates c->page
> updates c->freelist
> <cpu fetches c->tid>
> <cpu fetches c->freelist>
>
> node_match() succeeds even though
> current c->page wont
>
<migrates back to CPU 1>
> this_cpu_cmpxchg_double() only tests
> the object (freelist) and tid, both which
> will match, but the page that was tested
> isn't the right one.
>
Yes, it's very unlikely, but we are in the business of dealing with the
very unlikely. That's because in our business, the very unlikely is very
likely. Damn, I need to buy a lotto ticket!
-- Steve
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