[PATCH] powerpc/perf: Account for interrupts during PMC overflow for an invalid SIAR check

[Michael Ellerman]

On Thu, 6 Aug 2020 08:46:32 -0400, Athira Rajeev wrote:
> Performance monitor interrupt handler checks if any counter has overflown
> and calls `record_and_restart` in core-book3s which invokes
> `perf_event_overflow` to record the sample information.
> Apart from creating sample, perf_event_overflow also does the interrupt
> and period checks via perf_event_account_interrupt.
> 
> Currently we record information only if the SIAR valid bit is set
> ( using `siar_valid` check ) and hence the interrupt check.
> But it is possible that we do sampling for some events that are not
> generating valid SIAR and hence there is no chance to disable the event
> if interrupts is more than max_samples_per_tick. This leads to soft lockup.
> 
> [...]

Applied to powerpc/fixes.

[1/1] powerpc/perf: Fix soft lockups due to missed interrupt accounting
      https://git.kernel.org/powerpc/c/17899eaf88d689529b866371344c8f269ba79b5f

cheers