Re: [PATCH v1 1/6] perf: Disable PMU around address filter adjustment

[Peter Zijlstra]

On Tue, Jun 12, 2018 at 10:51:12AM +0300, Alexander Shishkin wrote:
> If the PMU is used for AUX data sampling, the hardware event that triggers
> it may come in during a critical section of address filters adjustment (if
> it's delivered as NMI) and in turn call the address filter sync code,
> causing a spinlock recursion.

Can you detail that a little more? How can sampling _ever_ get down that
path?