On Mon, Apr 24, 2017 at 01:00:18PM +0200, PaX Team wrote: > On 24 Apr 2017 at 10:32, Peter Zijlstra wrote: > > Also, you forgot nr_cpus in your bound. Afaict the worst case here is > > O(nr_tasks + 3*nr_cpus). > > what does nr_cpus have to do with winning the race? The CPUs could each run nested softirq/hardirq/nmi context poking at the refcount, irrespective of the (preempted) task context. > > Because PaX does it, is not a correctness argument. And this really > > wants one. > > heh, do you want to tell me about how checking for a 0 refcount prevents > exploiting a bug? Not the point. All I said was that saying somebody else does it (anybody else, doesn't matter it was you) isn't an argument for correctness.
